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Plants in a Changing World Integration of Photosynthesis, Adaptation and Development
6 – 8 November 2019, Helsinki, Finland
Program
General Information
Wed, 6 Nov 2019
Meeting Room 302 - 303
SESSION 1
15:45 Welcome reception with tea and coffee
16:20 Welcome address
CoE Chair Eva-Mari Aro (University of Turku) & CoE Co-chair Jaakko Kangasjärvi (University of Helsinki)
Session chairs: Kirk Overmyer & Natalia Battchikova
16:30-17:00 Cheryl Kerfeld (Michigan State University, USA) Building on new insights into carboxysome structure, function and dynamics
17:00-17:30 Marc Nowaczyk (Ruhr-Universität Bochum, Germany) Structural adaptations of photosynthetic complex I enable ferredoxin-dependent
electron transfer
17:30-18:00 Hannes Kollist (University of Tartu, Estonia)
Stomatal CO2 signaling for designing water-saving plants
18:00-18:30 Frank Van Breusegem (VIB-UGent Center for Plant Systems Biology, Belgium) Mining for protein S-sulfenylation in Arabidopsis uncovers redox-sensitive sites
18:30-19:00 Silke Robatzek (Ludwig-Maximilians-University Munich, Germany) How PRR signaling regulates immunity
19:00-19:30 Simone Ferrari (University of Rome Sapienza, Italy) Peroxidase-mediated reactive oxygen species at the intersection between plant cell
wall integrity, growth and resistance to biotic and abiotic stresses
19:30 Poster setup
Thu, 7 Nov 2019
Sirkus Room
SESSION 2
Session chairs: Mikael Brosché & Eevi Rintamäki
08:00-09:00 Poster setup
09:00-09:30 Donald Ort (University of Illinois, USA)
Improving photosynthetic efficiency for improved crop yield
09:30-10:00 Eva-Mari Aro (University of Turku, Finland) Regulation of photosynthetic light reactions – an evolutionary view
10:00-10:30 Alan Schulman (University of Helsinki, Finland) A path towards climate resilience for barley
10:30-10:45 Cezary Waszczak (University of Helsinki, Finland) The role of GDP-L-fucose biosynthesis in stomatal closure
10:45-11:00 Lauri Nikkanen (University of Turku, Finland) Flavodiiron proteins and NDH-1 cooperatively maintain the redox poise of the
photosynthetic electron transfer chain during fluctuations in light intensity and
carbon availability in Synechocystis
11:00-11:30 Coffee break + poster session
11:30-12:00 Philip M. Mullineaux (University of Essex, UK) The regulation of photosynthetic capacity in high light exposed leaves. Where does
retrograde signalling fit in?
12:00-12:30 Yagut Allahverdiyeva-Rinne (University of Turku, Finland) Redirecting photosynthetic electrons into targeted chemicals
12:30-13:00 Claudia-Nicole Meisrimler (University of Canterbury, New Zealand) Plant membrane-associated NAC transcription factors – key player in fast stress
response mechanism?
13:00-14:00 Lunch
SESSION 3
Session chairs: Pauli Kallio & Kaisa Nieminen
14:00-14:30 Lecture sponsored by the EMBO Young Investigator
Programme:
Emmanuelle Bayer (National Centre for Scientific Research,
Bordeaux, France)
Staying tight: membrane contact at plasmodesmata
intercellular junctions
14:30-15:00 Ari Pekka Mähönen (University of Helsinki, Finland) Stem cell regulation in the Arabidopsis root vascular cambium
15:00-15:30 Jaakko Kangasjärvi (University of Helsinki, Finland) Coordination of chloroplastic and mitochondrial ROS signaling in stress
acclimation
15:30-15:45 Melis Kucukoglu (University of Helsinki, Finland) Cytokinin regulation of cambium activity and wood formation in hybrid aspen
15:45-16:00 Peter Gollan (University of Turku, Finland) Photosynthetic redox homeostasis triggers chloroplast signalling and influences
plant metabolism
16:00-16:30 Coffee break + poster session
SESSION 4
Session chairs: Paula Mulo & Alexey Shapiguzov
16:30-17:00 Barry Pogson (Australian National University, Australia) Intracellular communication of abiotic stress: from model systems to crops
17:00-17:30 Saijaliisa Kangasjärvi (University of Turku, Finland) Protein phosphatase 2A as a regulator of plant stress responses
17:30-18:00 Michael Wrzaczek (University of Helsinki, Finland) CRK2 coordinates abiotic and biotic stress responses
18:00-18:15 Pawel Roszak (Sainsbury Laboratories Cambridge, UK) Phloem development at the single-cell resolution
18:15-18:30 Martina Jokel-Toivanen (University of Turku, Finland) Improving H2 photoproduction – lessons learned from photosynthesis research
18:30-19:30 Poster session
19:30- Conference dinner
Fri, 8 Nov 2019
Sirkus Room
SESSION5
Session chairs: Hiroaki Fujii & Triin Vahisalu
09:00-09:30 Ove Nilsson (Umeå Plant Science Centre, Sweden) FT paralogs control the annual growth cycle and latitudinal adaptation in Aspen
trees
09:30-10:00 Esa Tyystjärvi (University of Turku, Finland) Plastoquinone, state transition and gene expression
10:00-10:30 Arun Sampathkumar (Max Planck Institute for Molecular Plant Physiology, Germany) The mechanics of invaginations and outgrowths in plant cells
10:30-10:50 Roosa Laitinen (Max Planck Institute of Molecular Plant Physiology, Germany) What causes altered shoot growth in Arabidopsis hybrids?
10:50-11:10 Paula Elomaa (University of Helsinki, Finland) Developmental patterning of head-like inflorescences in Asteraceae
11:10-11:30 Coffee break + poster session
11:30-12:00 Christine Raines (University of Essex, UK) Future proofing plant productivity by engineering leaf photosynthetic carbon
metabolism to future proof
12:00-12:30 Ykä Helariutta (University of Helsinki, Finland; Sainsbury Laboratories Cambridge,
UK) Integration of hormonal and transcriptional control during vascular development
12:30-13:00 Farewell
13:00 Lunch + departure
Poster removal
Posters
Poster boards will be 103 cm width x 220 cm height (fabric surface area: width 96 cm, height 117 cm).
A0 size portrait format is recommended.
The boards will be available in the Sirkus foyer for mounting the posters from Wednesday 6 November, 19:30.
All the materials necessary for fixing posters will be available at the poster boards. Please see the number of
your poster in our abstract book. Presenters should be available for questions and discussion near their posters
during the coffee breaks and evening poster session as much as possible. Authors are kindly asked to dismount
their posters on Friday 8 November after the poster session or at the end of the meeting.
The Best Poster prize consisting of a certificate and freely chosen antibody from Agrisera will be announced
during the final remarks at the end of the conference.
Presentations
The recommended file type to be used for all presentations is PowerPoint. We kindly ask our speakers to
embed all images, videos and fonts in the ppt, pttx file.
Please bring your presentation on a USB stick and save a copy in your email so that it is stored online.
Please save your presentation as “Name Of Presenter_Date_Time_First four words of Title” (e.g.
Smith_24August_0900_ Regulation of photosynthetic light.pptx (or .ppt)).
Speakers are requested to upload their presentation on to the session PC and report to the session chair 15-30
minutes before the start of the session and/or during the coffee breaks. Session chairs will be in the room to
assist with technical issues and to help uploading presentations onto the computer.
All PCs available during the event operate on Windows system. Use of your own laptop with the conference
projection system is strongly discouraged.
Privacy
Due to much of the data being presented being unpublished, and to protect attendee privacy, there is no
photography or videotaping allowed at this event.
Wifi Access
Free of charge. Network: Paasitorni, Password: Paasi123+
Abstracts
Oral presentations
Building on New Insights into Carboxysome Structure, Function and
Dynamics
Cheryl A. Kerfeld
MSU-DOE Plant Research Laboratory & Department of Biochemistry & Molecular Biology, Michigan State University
& Environmental Genomics & Systems Biology & Molecular Biophysics & Integrated Bioimaging Divisions, Berkeley
National Laboratory, USA, www.kerfeldlab.org
Cyanobacteria evolved a CO2 Concentrating Mechanism to enhance the carbon fixation activity of the inefficient
enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). A central component of cyanobacterial Carbon
Concentrating Mechanism is a proteinaceous organelle, the carboxysome. The carboxysome is a self-assembling
metabolic module for CO2 fixation that sequesters several proteins including Carbonic Anhydrase, RuBisCO—and a
recently identified RuBisCO Activase-like protein within a selectively permeable protein shell, thereby concentrating
substrates and protecting RuBisCO from the oxygen generated by the light reactions. Recent evidence suggests that the
composition of the carboxysome is dynamic and responsive to environmental conditions. Because carboxysomes and
other architecturally related bacterial microcompartments function to organize reactions that require special conditions
for optimization, including the sequestration of substrates, cofactors, or toxic intermediates and the protection of oxygen
sensitive enzymes, they are the subject of considerable attention as templates for designing metabolic modules for
bioengineering.
Structural adaptations of photosynthetic complex I enable ferredoxin-
dependent electron transfer
Marc M. Nowaczyk
Plant Biochemistry, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany.
Photosynthetic complex I enables cyclic electron flow around photosystem I, a regulatory mechanism for photosynthetic
energy conversion. We report a 3.3-Å resolution cryo-EM structure of photosynthetic complex I from the
cyanobacterium Thermosynechococcus elongatus. The model reveals structural adaptations that facilitate binding and
electron transfer from the photosynthetic electron carrier ferredoxin. By mimicking cyclic electron flow with isolated
components in vitro, we demonstrate that ferredoxin directly mediates electron transfer between photosystem I and
complex I, instead of using intermediates such as NADPH. A large rate constant for association of ferredoxin to complex
I indicates efficient recognition, with the protein subunit NdhS being the key component in this process.
Schuller JM, Birrell JA, Tanaka H, Konuma T, Wulfhorst H, Cox N, Schuller SK, Thiemann J, Lubitz W, Sétif P,
Ikegami T, Engel BD, Kurisu G, Nowaczyk MM (2018) Science 363:257-260
Stomatal CO2 signaling for designing water-saving plants
Hannes Kollist
Plant Signal Research Group, Institute of Technology, University of Tartu, Tartu, 50411, Estonia
plantsignalresearch.com, plantinvent.com
Plants are continually balancing the influx of CO2 for photosynthesis against the loss of water through stomatal pores in
their leaves. Reduced CO2 levels in the leaf indicate a shortage of substrate for photosynthesis and trigger stomatal
opening, while above-ambient CO2 leads to stomatal closure. Plant hormone abscisic acid (ABA) is involved in the
regulation of stomatal closure during drought but it also has a role in CO2 -induced stomatal regulation. To breed crops
that will use less water in a future climate we need to know how plants sense and respond to ABA and CO2. To study
these processes, we are carrying out mutant screen and are developing gas exchange technologies for plant analysis. I
will cover recent advances in understanding mechanisms of ABA-dependent and ABA-independent CO2 -induced
stomatal movements. The role of protein kinases MPK4, MPK12, HT1, OST1, GHR1 in the regulation of guard cell
anion channel SLAC1 and show how this mechanism can be used for improving plant water management in future
world with elevated CO2.
Mining for protein S-sulfenylation in Arabidopsis uncovers redox-sensitive
sites
Frank Van Breusegem
Department of Plant Biotechnology and Bioinformatics, Ghent University & VIB Centre of Plant Systems Biology,
Ghent, Belgium
Reactive oxygen species (ROS) and especially hydrogen peroxide, are potent signaling molecules that activate cellular
defense responses. Hydrogen peroxide can provoke reversible and irreversible oxidative posttranslational modifications
on cysteine residues of proteins that act in diverse signaling circuits. The initial oxidation product of cysteine, sulfenic
acid, has emerged as a biologically relevant posttranslational modification, because it is the primary sulfur oxygen
modification that precedes divergent series of additional modifications. Although many proteins have been identified as
S-sulfenylation targets in plants, site-specific mapping and quantification remain largely unexplored. By means of a
peptide-centric chemoproteomics approach, we mapped 1,537 S-sulfenylated sites on more than 1,000 proteins in
Arabidopsis thaliana cells. Proteins involved in RNA homeostasis and metabolism were identified as hotspots for S-
sulfenylation.
How PRR signaling regulates immunity
Michaela Kopischke1,2, Yi Liu1, Timothy Hawkins3, Tobias Maierhofer4, Jan Sklenar2, Frank Menke2, Dietmar Geiger4,
Patrick Hussey3, Rainer Hedrich4, Silke Robatzek1,2
1Biocenter, LMU München, DE 2The Sainsbury Laboratory, Norwich Research Park, UK 3University of Durham, UK 4Biocenter, University of Würzburg, DE
Our interest is to understand how plants defend themselves against infection and how successful pathogens overcome
plant immunity. Perception of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs)
results in the closure of stomata, leaf epidermal pores that represent entry gates for pathogens when open. We identified
a guard cell expressed anion channel as a direct phospho-regulatory target of the PRR complex in acute MAMP-induced
stomatal closure and anti-fungal immunity. Further, we show that PRR signaling, in addition to triggering acute stomatal
closure, sustains the closure of stomata. The latter requires activation-dependent regulation of a FLS2-associated RAB7
GTPase and its NET4 effectors, which are actin-to-tonoplast tethers. These provide examples of acute and sustained
anti-microbial immunity in plant body surface protection.
This work is supported by the Gatsby Charitable Foundation, the European Research Council (ERC), and the German
Research Foundation (DFG).
Peroxidase-mediated reactive oxygen species at the intersection between plant
cell wall integrity, growth and resistance to biotic and abiotic stresses
Riccardo Lorrai1, Fedra Francocci1, Lorenzo Fimognari2, Giulia De Lorenzo1, Yumiko Sakuragi2, Simone Ferrari1
1 Dipartimento di Biologia e Biotecnologie “Charles Darwin”, Sapienza Università di Roma, 00185 Rome, Italy 2 Copenhagen Plant Science Center Frederiksberg, Denmark; Department of Plant and Environmental Sciences,
University of Copenhagen Frederiksberg, Denmark
Cell wall composition plays important roles in plant growth and responses to environmental stresses. Recent evidence
indicates that changes in cell wall integrity (CWI), that can occur both under physiological circumstances and in
response to abiotic and biotic stresses, trigger responses partly overlapping with those induced by microbial elicitors
and affecting both resistance and growth. For instance, plants with altered homogalacturonan (HGA) show enhanced
expression of defenses and increased resistance to the fungal pathogen Botrytis cinerea, as well as reduced growth.
However, the mechanisms linking CWI, growth and defense, and the contribution of specific wall components to these
responses, are still unclear. We have previously found that reactive oxygen species (ROS) mediated by the Arabidopsis
class III peroxidase AtPRX71 restrict cell expansion in response to CWI. Here we show that HGA modifications lead
to a reduction in cuticle permeability, which depends on AtPRX71 and is suppressed by abscisic acid (ABA). Notably,
resistance to B. cinerea in these plants is also suppressed by ABA, but not by mutations in AtPRX71. The relationships
between cell wall composition, ROS, cuticle deposition and resistance to pathogens will be discussed.
Improving Photosynthetic Efficiency for Improved Crop Yield
Donald R. Ort
Institute for Genomic Biology, University of Illinois, Urbana, IL USA
Feeding the world’s current population already requires 15% of the total net primary productivity of the globe’s land
area and that will need to increase to 25% in order to meet the projected increase in agricultural demand this century.
This near doubling of food production will have to be accomplished on globally declining acreage and during a time in
which there will be ever increasing demand on cultivated lands for the production of bioenergy crops, while in the face
of a changing global environment that has already resulted in decreasing global yield of some of the world’s most
important food crops. The yield potential of crops is determined by their efficiency of capturing available light energy
( i), the efficiency of converting intercepted light into biomass ( c), and the proportion of biomass partitioned into
grain (η). The remarkable yield gains of the Green Revolution in the middle of the 20th century resulted from plant
breeders bringing η and i for major crops close to their theoretical maxima, leaving improved photosynthetic efficiency
as the only yield potential determinant with sufficient capacity to double crop productivity. Opportunities to improve
photosynthetic efficiency exist in readapting photosynthesis to the rapid changes in atmospheric composition and
temperature, in redesigning photosynthesis for agricultural production and in applying synthetic biology to bypass
evolutionary limitations and inefficiencies in photosynthesis. Recent work using a synthetic biology approach to lower
the energetic cost of photorespiration will be presented.
Regulation of photosynthetic light reactions – an evolutionary view
Eva-Mari Aro
Department of Biochemistry, University of Turku, Finland
The photosynthetic electron transfer chain in the thylakoid membrane is pretty similar in all oxygen evolving
photosynthetic organisms, from prokaryotic cyanobacteria to higher plants, whilst a number of different regulation
mechanisms has evolved to protect the photosynthetic apparatus against photodamage. Highly oxidative photosystem
(PS) II is susceptible to excess light and the highly reducing PS I is susceptible to excess electrons that induce irreversible
damage to PSI Fe-S clusters. Several regulation mechanisms function in close interaction to respond to specific changes
in environmental cues. It has become evident that different evolutionary groups of oxygenic photosynthetic organisms
have harboured either unique mechanisms or the proteins responsible for a particular type of protection have drastically
changed during evolution. For example, the evolution of the PGR5/PGRL1A,B protein- and ΔpH-dependent slow-down
of the electron flow via the Cytb6f complex has gradually replaced the specific flavodiiron proteins most abundantly
present in cyanobacteria. Only angiosperms can survive in harsh environments without flavodiiron proteins, whilst green
algae, mosses, ferns and gymnosperms rely at least partially, and cyanobacteria completely, on flavodiiron proteins as
electron sinks in photoprotection of PSI. Likewise, the thylakoid protein phosphorylation-based regulation in different
evolutionary groups of oxygenic photosynthetic organisms revealed clear changes from cyanobacteria to green algae,
and further upon the movement of life from oceans to the land, as depicted in mosses and ferns. Yet, the evolution of
this regulation mechanism continued upon development of gymnosperms and even further in angiosperms. The new
class of thylakoid phosphor-proteins, the CURT1 proteins, were characterised in functional regulation and lateral re-
organisation of the thylakoid membrane complexes. Concomitant and detailed analysis of photosynthesis-induced ROS
production as well as the consequences on nuclear gene expression is revealing how photosynthesis regulates plant
acclimation by several distinct retrograde signalling pathways. Understanding of thylakoid redox regulation in different
evolutionary groups of photosynthetic organisms opens up new ways to re-construct the regulation systems for varying
environments and for improved efficiency of the photosynthetic apparatus in food, feed and fuel production.
A path towards climate resilience for barley
Alan Schulman
Institute of Biotechnology, University of Helsinki & Natural Resources Institute, Finland
European agriculture anticipates an unprecedented combination of stress factors, production threats and quality needs
due to climate change. Various regions of Europe will be affected differently. Barley & wheat domestication, and
landrace formation in Europe, were under very different climates than those emerging now. Alleles needed for
sustainable, resilient, quality yields in a changed climate are likely not combined in current haplotypes of elite barley
cultivars. These alleles are likely found in diverse landraces and wild relatives in the Mediterranean basin and Fertile
Crescent -- areas that prefigure expected climate change. New precision, high-throughput phenotyping tools are essential
to find trait-allele associations needed for future-climate breeding. Combining genetics, genomics, modelling, molecular
biology, morphology, and physiology, we and our collaborators in the FACCE-JPI project ClimBar have taken an
interdisciplinary approach to develop a strategy for breeding an increased resilience to climate change in barley. We
have focused on identifying genome regions, genes, and alleles conferring the traits needed to breed resilient barley
varieties adapted to the climatic conditions predicted for 2070 in different European environments. Adapted, resilient
germplasm created using ClimBar data, tools and models will provide food-chain security, economic stability and
environmental sustainability.
The role of GDP-L-fucose biosynthesis in stomatal closure
Cezary Waszczak
Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Centre, Faculty of Biological and
Environmental Sciences, University of Helsinki, Finland
Guard cells control the size of stomatal pores. Exposure to multiple environmental factors activates guard cell signaling
leading to stomatal closure, therefore, guard cells determine the water use efficiency and stress tolerance. Accumulation
of reactive oxygen species (ROS) in the apoplast of guard cells, is both, necessary, and sufficient, to initiate the process
of stomatal closure. Thus, the exposure to external sources of ROS, such as ozone (O3), serves as an efficient tool to
study stomatal function. Response to ozone triggers rapid stomatal closure that prevents the entry of ozone into the plant.
Plants impaired in stomatal closure receive high doses of ozone, ultimately leading to leaf damage. On the basis of this
mechanism we have conducted a broad forward genetics screen aiming at identification of novel stomatal regulators.
Next to the ozone susceptibility, for the most prominent mutants we have performed detailed gas exchange-based assays
to investigate stomatal responses to a variety of stimuli. Additionally, targeted sequencing of genomic regions encoding
known stomatal regulators has been performed to avoid potential re-discoveries. The screen yielded ~50 mutants
impaired in stomatal closure. The causative mutations in one of them was mapped to a genomic region encoding
MURUS1 (MUR1), an enzyme catalyzing the first committing step in de-novo fucose biosynthesis pathway. Plants
lacking MUR1 were unresponsive to the majority of stomata-closing stimuli while the stomatal opening process
appeared functional. Through a further genetic analysis we provide an insight into the role of fucose biosynthesis in
guard cell function.
Flavodiiron proteins and NDH-1 cooperatively maintain the redox poise of
the photosynthetic electron transfer chain during fluctuations in light
intensity and carbon availability in Synechocystis
Lauri Nikkanen1, Anita Santana Sanchez, Maria Ermakova and Yagut Allahverdiyeva1 1 University of Turku, Turku, Finland
In photosynthetic organisms apart from Angiosperms, flavodiiron proteins (FDPs) catalyze light-dependent reduction
of O2 to H2O (Mehler-like reaction) in order to alleviate electron pressure on PSI and to protect it from photodamage
in fluctuating light conditions. In Synechocystis sp. PCC 6803, four FDP isoforms exist that function in O2
photoreduction as heterodimers of either Flv1 and 3 or Flv2 and 4. The NAD(P)H dehydrogenase-like complex (NDH-
1), in turn, is essential for Ci uptake, respiration and cyclic electron transfer (CET) from Ferredoxin (Fd) to
plastoquinone (PQ). Four types of NDH-1 haven been characterized in Synechocystis, with NDH-11 and NDH-12
suggested to function in respiration and CET, and NDH-13 and NDH-14 in CO2 uptake. Here, we have characterized
triple mutants lacking an Flv and the D1 and D2 subunits of NDH-1, resulting in deficiency of NDH-11 and NDH-12.
Our results show that strong interdependency and crosstalk exists between Flv’s and the NDH-1. While ΔFlv single
mutants and ΔNdhD1/D2 double mutants can acclimate to a change of growth conditions from low light / high CO2 to
high light / low CO2 and grow like WT cells, the ΔFlv/NdhD1/D2 triple mutants are unable to survive the shift. Our
results demonstrate that the functions of Flv’s and NDH-1 are coordinated in a dynamic manner that allows efficient
oxidation (and protection from photodamage) of PSI under variable light conditions and carbon availability. We suggest
that Flv1/3 provides an electron valve for fast time-scale alleviation of PSI over-reduction while NDH11-2 would
function during prolonged electron pressure on PSI.
The regulation of photosynthetic capacity in high light exposed leaves. Where
does retrograde signalling fit in?
Philip M. Mullineaux
School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ UK
In the last few years, we have been working to identify the signalling processes that control the photosynthetic capacity
of mature leaves. This has led to conclude that two transcription (co) factors, ELONGATED HYPOCOTYL5 (HY5)
and B-BOX ZINC FINGER PROTEIN, BBX32 are the critical positive and negative regulators respectively of the rise
in photosynthetic capacity associated with repeated exposure to episodes of HL. This signalling is initiated by
CRYPTOCHROME1 and onward signalling to BBX32 and HY5 is mediated by a COP1/SPA complex. BBX32 and
HY5 control the expression of photosynthesis associated nuclear genes, which are suggested to lead to increases in
photosynthetic efficiency and capacity. However, our hypothesis is that first hours of exposure to HL trigger signalling
from chloroplasts to the nucleus that sets in train the processes leading to increased photosynthetic capacity several days
later. Several potential operating signals originating from chloroplasts have been proposed. One proposed signal is
hydrogen peroxide (H2O2) produced by chloroplasts in a light-dependent manner, which we consider to be a candidate
for initiating this acclimation to HL. We have used different types of genetically-encoded fluorescent H2O2and peroxide
sensors, to show that in photosynthetic cells of both Arabidopsis and Nicotiana benthamiana, exposure to high light
(HL) increased H2O2production in chloroplast stroma, cytosol and nuclei. In all cases, the close association of some
chloroplasts with the nucleus may contribute to the specificity of H2O2-directed signalling. Therefore, we have proposed
that direct H2O2transfer from chloroplasts to nuclei, avoiding the cytosol, enables photosynthetic control over gene
expression and we propose that one target for this regulation is the HY5 and BBX32 networks described above.
Therefore, the challenge now is to determine if and how retrograde signalling from chloroplasts fits into the regulation
of photosynthetic capacity, thus unifying the two part of the work in my laboratory.
Redirecting photosynthetic electrons into targeted chemicals
Yagut Allahverdiyeva
Photosynthetic microbes group, Molecular Plant Biology unit, Department of Biochemistry, University of Turku, Turku,
Finland
Photosynthetic aquatic microorganisms, cyanobacteria and algae, are considered as third generation truly sustainable
feedstock for blue biorefineries. Proof-of-concept trials for dozens of genetically-engineered photosynthetic organisms
hosting novel synthetic pathways for production of desired chemicals are currently available. However, most of the
available systems demonstrate low solar-to-chemicals conversion efficiencies and need significant improvements to
serve as industrial-scale production platforms. We apply two different strategies to improve photosynthetic production
system: enhancement of photosynthetic yield and development of efficient solid-state production system.
Photosynthetic organisms possess, among other protection mechanisms, an extensive network of auxiliary electron
transport pathways to regulate photosynthesis. These routes can be considered as a “waste” of photosynthetic electrons
or reducing power under specific conditions. Flavodiiron proteins (FDPs) are powerful electron sink functioning in O2
photoreduction (called the Mehler-like reaction), thus safeguarding PSI under fluctuating light intensities
(Allahverdiyeva et al. 2013, Jokel et al. 2018). We revealed a tight interplay between FDPs and other bioenergetic
processes and auxiliary electron transport pathways in model cyanobacteria (unicellular non-N2 fixing Synechocystis
sp. PCC 6803, heterocystous N2-fixing Anabaena sp. PCC7120) and in a model green alga, C. reinhardtii. Switching
between different trophic modes is an advantageous feature which provides metabolic flexibility for cyanobacteria. We
demonstrate that a small heme protein, Cytochrome (Cyt) cM, downscales photosynthesis under photomixotrophic
conditions. Growth advantage of ΔcytM Synechocystis arises from circumventing the over-reduction of the intersystem
electron chain.
We developed a solid-state production platform consisting of immobilized algal/cyanonacterial thin films, which act as
‘artificial leaf’ stimulating efficient conversion of solar energy into targeted chemicals (e.g. ethylene, H2, lactone). The
system overcomes the bottlenecks of suspension cultures, thus changing a paradigm in algal biotechnology. Strong
limitation of cell growth due to entrapment in the rigid matrix allows application of phototrophs as true biocatalysts
funneling light energy into the desired products, instead of wasting it to cell growth and metabolism.
Reference:
Santana-Sanchez A et al. (2019) Flavodiiron proteins 1-to-4 function in versatile combinations in O2 photoreduction in
cyanobacteria. eLife 8:e45766.
Jokel M et al. (2018). Hunting the main player enabling Chlamydomonas reinhardtii growth under fluctuating light. Plant J. 94:822-
835
Jämsä M et al. (2018) Versatile templates from cellulose nanofibrils for photosynthetic microbial biofuel production, J Mater Chem
A, 6:5825-5835
Plant membrane-associated NAC transcription factors – key player in fast
stress response mechanism?
Claudia-Nicole Meisrimler1, Alexandra J.E. Pelgrom2, Guido Van den Ackerveken2
1Molecular Plant Biology, School of Biological Sciences, University of Canterbury, New Zealand 2Plant–Microbe Interactions, Department of Biology, Utrecht University, the Netherlands
NAC transcription factors are one of the largest families of transcriptional regulators in plants with important roles in
plant stress responses. The sub-group of membrane-associated NAC TFs (maNAC TFs) contain in addition to the NAC
domain a transmembrane domain and a variety of motifs and targets for post-translational modifications – allowing a
tight regulation of the maNAC signal transduction pathways. In our recent work, we identified the ER localized lettuce
maNAC, LsNAC069, as a target of two Bremia lactucae RXLR effector proteins, BLR05 and BLR09. Interaction of
LsNAC069 with the effectors did not require the N-terminal NAC domain but depended on the C-terminal region
including the transmembrane domain. In Y2H experiments B. lactucae effectors also interacted with maNAC TFs from
Arabidopsis and potato suggesting that maNACs are conserved effector targets. Furthermore, we identified
Phytophthora capsici culture filtrate and the osmolyte PEG as activators for the LsNAC069 nuclear relocalization. The
relocalization was significantly reduced by the Ser/Cys-protease inhibitor TPCK and the co-expression of the two
effectors HA-BLR05 and HA-BLR09. Silencing of LsNAC069 in lettuce showed no effect on Bremia resistance, but
surprisingly, decreased susceptibility to the leaf blight inducing bacterium Pseudomonas cichorii and wilting effects
under moderate drought stress. These results indicate a versatile role of the LsNAC069 signal transduction pathway for
plant-pathogen-interaction and drought-stress response.
EMBO Young Investigator sponsored lecture:
Staying tight: membrane contact at plasmodesmata intercellular junctions
Emmanuelle Bayer
Laboratoire de Biogenèse Membranaire UMR5200 CNRS/Université de Bordeaux, France
In plants, plasmodesmata pores, are anchored in the cell wall, interconnect virtually every single cell within the plant
body, establishing direct membrane and cytoplasmic continuity from cell-to-cell, a situation unique to plants.
Plasmodesmata control the flux of molecules (small RNAs, transcription factors, hormones and metabolites) between
cells and in addition of acting as “conduits” they can also function as signalling hubs capable of generating and relaying
signalling from cell-to-cell through receptor activities. Plasmodesmata are indispensable for plant life, and participate
to a wide range of plant-related biological processes, which extent from plant development, tissue patterning to
biotic/abiotic stress responses, cell defence signalling and distribution of photo-assimilates. Plasmodesmata architecture
is unique and poses many biophysical, structural and functional questions. Inside the pores the endoplasmic reticulum
(ER) and the plasma membrane (PM) are highly curved, come are remarkably close to each other and are physically
tethered. To date the function of ER-PM contacts at plasmodesmata remains an enigma. We don’t know how and why
the two organelles come together at plasmodesmata cellular junctions. The aim of our group is to understand the
molecular mechanisms underlying plasmodesmata membrane organisation and remodelling events, and provide a link
between the pores unique membrane architecture and the regulation of cell-to-cell communication. For that we integrate
interdisciplinary approaches ranging from molecular dynamics and ultra-high resolution 3D imaging into molecular cell
biology of plant cell-to-cell communication.
References
Grison MS, Kirk P, Brault M, Na Wu X, Schulze WX, Benitez-Alfonso Y, Immel F, Bayer EM (2019) Plasma membrane associated
Receptor Like Kinases relocalise to plasmodesmata in response to osmotic stress. Plant Physiol. 181:142-160
Brault ML, Petit JD, Immel F, Nicolas WJ, Glavier M, Brocard L, Gaston A, Fouché M, Hawkins TJ, Crowet J, Grison SM, Germain
V, Rocher M, Kraner M, Alva V, Claverol S, Paterlini A, Helariutta Y, Deleu M, Lins L, Tilsner J, Bayer EM (2019) Multiple C2
domains and transmembrane region proteins (MCTP) tether membranes at plasmodesmata. EMBO Rep. e47182, p1–26
Yan D, Yadav SR, Paterlini A, Nicolas WJ, Petit JD, Brocard L, Belevich I, Grison MS, Vaten A, Karami L, El-Showk S, Lee JY,
Murawska GM, Mortimer J, Knoblauch M, Jokitalo E, Markham JE, Bayer EM, Helariutta Y. (2019) Sphingolipid biosynthesis
modulates plasmodesmal ultrastructure and phloem unloading. Nat Plants 5: 604–615
Nicolas W, Grison MS, Trépout S, Gaston A, Fouché M, Cordelières F, Oparka K, Tilsner J, Brocard L, & Bayer EM. (2017)
Architecture and permeability of post-cytokinesis plasmodesmata lacking cytoplasmic sleeve. Nature Plants. 3:17082.
Stem cell regulation in the Arabidopsis root vascular cambium
Ondřej Smetana1,2, Riikka Mäkilä1,2, Munan Lyu1,2 and Ari Pekka Mähönen1,2
1 Institute of Biotechnology, HiLIFE, University of Helsinki, Finland 2 Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Finland
Vascular cambium is a secondary meristem producing xylem and phloem along thickening plant organs. By combining
cell lineage tracing with molecular genetics, we recently showed that cells with a xylem identity direct adjacent vascular
cambial cells to divide and function as stem cells (Smetana et al 2019). Therefore, we proposed that xylem-identity cells
constitute an organizer. Molecular studies revealed that the organizer is defined by local auxin maximum, and
subsequent expression of class III homeodomain-leucine zipper (HD-ZIP III) family transcription factors. HD-ZIP IIIs
promote xylem identity and cellular quiescence of the organizer cells. Additionally, the organizer maintains phloem
identity in a non-cell-autonomous manner. In line with this dual role of the organizer cells, xylem and phloem originate
from a single, bifacial stem cell in each radial cell file, which confirms the classical theory of a uniseriate vascular
cambium (Sanio 1873). Clones with high levels of ectopically induced auxin signalling differentiate as xylem vessels;
these clones induce cell divisions and the expression of cambial and phloem markers in the adjacent cells. These data
suggest that a local auxin signalling maximum is sufficient to specify a stem-cell organizer of vascular cambium
(Smetana et al 2019). As a follow up, we have been studying whether other cambial regulators interact with the factors
defining the organizer. The latest discoveries of these studies will be presented in the meeting.
Coordination of chloroplastic and mitochondrial ROS signaling in stress
acclimation
Jaakko Kangasjärvi
Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, and
Viikki Plant Science Center, University of Helsinki, FI-00014 Helsinki, Finland
Plant chloroplasts and mitochondria supply the cell with energy and metabolites. ROS are formed in these organelles in
the electron transfer chains. Signaling from chloroplasts and mitochondria is partly dependent on ROS, which regulate
many aspects of development, stress signaling, systemic responses, and programmed cell death. This communication
network affects gene expression in the nucleus where numerous signals are perceived and integrated. However, the
molecular mechanisms of the coordinated action of the two organelles in response to ROS-producing environmental
cues, such as changing light intensity or pathogen responses are poorly understood. The Arabidopsis RCD1 protein
appears to serve as scaffold for nuclear protein complex formation. RCD1 interacts with transcriptional regulators of
ROS-related mitochondrial retrograde signaling. Inactivation of RCD1 increases expression of the Mitochondrial
Dysfunction Stimulon (MDS) genes resulting in accumulation MDS gene products in the mitochondria. This affect
respiration and energy metabolism, and alters electron transfer in the chloroplasts, leading to decreased chloroplastic
ROS production and increased protection of photosynthetic apparatus. RCD1-dependent regulation is also
involved in 3'-phosphoadenosine 5'-phosphate (PAP)-mediated retrograde signaling from chloroplasts; a significant
overlap exists between genes negatively regulated by RCD1, the MDS genes, and genes affected by PAP. Sensitivity
of RCD1 to organellar ROS provides feedback control of nuclear gene expression and RCD1 integrates retrograde
signals from both chloroplasts and mitochondria to exert its influence on nuclear gene expression. In addition, MDS
genes influence not only the mitochondria, but indirectly also the chloroplasts. Overall, RCD1 allows dialog between
retrograde signals from both organelles and appears to be involved in determining the balance between stress
acclimation, systemic responses, and programmed cell death.
Cytokinin regulation of cambium activity and wood formation in hybrid
aspen
Melis Kucukoglu1,2, Juha Immanen3, Kaisa Nieminen3, Olli-Pekka Smolander4, Rishikesh P. Bhalerao5, Ari Pekka
Mähönen1,2 and Ykä Helariutta1,2,6
1Institute of Biotechnology, University of Helsinki, Helsinki, Finland 2Organismal and Evolutionary Biology Research Programme (OEB), University of Helsinki, Helsinki, Finland 3Natural Resources Institute Finland (Luke), Helsinki, Finland 4Department of Chemistry and Biotechnology, Division of Gene Technology, Tallinn University of Technology,
Tallinn, Estonia 5Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, Swedish University of
Agricultural Sciences, Umeå, Sweden 6Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom
Radial expansion of the stems and roots in plants derives from the activity of the vascular cambium - a meristematic
tissue that contains the vascular stem cells and generates xylem (wood) on the inside and phloem on the outside.
Proliferation and differentiation of the vascular stem cells in the cambium is tightly regulated to achieve an organized
vascular development. A recent study from our group displayed that cambial cell division rate and biomass production
can be stimulated dramatically in hybrid aspen trees through overexpression of the cytokinin biosynthesis gene,
ISOPENTENYLTRANSFERASE 7 (IPT7). To understand how cytokinin orchestrates the cambium activity and wood
formation, we collected genome-wide profiling data from the wood-forming regions of wild-type (WT) and mutant trees
with enhanced cytokinin production, and from the stem of WT trees treated with cytokinin. As a result, several new
regulators of cambium development in hybrid aspen was identified. Currently we are studying the functions of these
candidate genes in trees through transgenic approach (i.e. using RNAi and tissue specific over-expression strategies).
Our recent results in this research avenue will be presented.
Photosynthetic redox homeostasis triggers chloroplast signalling and
influences plant metabolism
Peter J Gollan, Yugo Lima-Melo, Mikko Tikkanen, Eva-Mari Aro
Molecular Plant Biology, Department of Biochemistry, University of Turku, Finland
Photosynthetic light reactions operate as both sensor and transmitter, perceiving and communicating information about
the plant’s environment. Changes in environmental conditions can disturb the homeostasis within the photosynthetic
energy/electron transport system, leading to the formation of various signalling compounds in the chloroplast, especially
reactive oxygen species and oxidised metabolites, which ultimately reprogram the expression of nuclear genes. We have
used combinations of gene mutants and specific light treatments to study the effects of altered photosynthetic redox
balance on chloroplast signalling and primary metabolism. We found that increased excitation/reduction pressure on
photosystem II (PSII) upregulates signalling through lipid metabolites (oxylipins). Induction of oxylipin signalling
during stress recovery suggests an interaction with abiotic stress-induced pathways. Disruption of redox balance caused
by photoinhibition of photosystem I (PSI) was most severe under low light conditions, but also impaired normal abiotic
stress signalling in high light. Inhibition of PSI had a severe and protracted effect on carbon assimilation and metabolism.
Our results show that discreet signals derived from PSI or from PSII are integral for perceiving environmental
fluctuations through photosynthetic redox homeostasis.
Intracellular communication of abiotic stress: from model systems to crops
Barry Pogson
ARC Centre of Excellence in Plant Energy Biology, 134 Linnaeus Way, Australian National University, Canberra 2601
Australia
Abiotic stress such as excess-light and drought cause significant crop losses by reducing photosynthetic efficiency and
preventing yield potentials to be realized1. Management of the induction of oxidative stress tolerance involves
chloroplast retrograde signaling pathways to the nucleus that trigger stress response mechanisms1. Recovery from
temporary abiotic stresses is equally important as acclimation, as slow recovery from, or constitutive acclimation to,
stress can impair growth and yield4. We have shown that inactivation of a phosphatase, SAL1, by oxidative stress in
chloroplasts controls accumulation of its substrate, PAP (3′-phosphoadenosine 5′- phosphate) which acts as a chloroplast
stress retrograde signal2. We have also shown that the SAL1- retrograde pathway interacts with abscisic acid (ABA)
signaling to regulate stomatal closure and seed germination in Arabidopsis3. We have recently demonstrated
evolutionary conservation of this pathway and that a key component arose prior to the transition to land and the
development of stomata5. Indeed, PAP regulates guard cells in a range of crops and land plants5. As a consequence, we
have developed wheat lines lacking one or more of the SAL1 genes and are evaluating the growth, phenology,
glasshouse and field-based performance of the different genotypes.
1 Chan et al (2016) Ann Rev Plant Biology 67:25-53 2 Chan et al. (2016) PNAS 113: E4567-E4576 3 Pornsiriwong et al (2017) eLIFE 6: e23361 4 Crisp et al 2016) Science Advances 2: e1501340 5 Zhao et al (2019) PNAS, 116: 5015-5020
Protein phosphatase 2A as a regulator of plant stress responses
Saijaliisa Kangasjärvi
Molecular Plant Biology, University of Turku, Finland
Light-dependent organellar retrograde signals are vital in determining appropriate stress reactions in plants. We have
identified Protein Phosphatase 2A (PP2A) as a cytosolic factor that modulates light acclimation and pathogenesis
responses in Arabidopsis thaliana. PP2A regulatory subunit B’γ (PP2A-B’γ) is required to maintain growth and prevent
premature developmental leaf senescence under favorable conditions. On a molecular level, PP2A-B’γ controls a
network of proteomic and metabolic alterations elicited by organellar stress signals. Genetic, proteomic and
metabolomic approaches revealed that PP2A-B’γ directly regulates multiple phosphoproteins that are elicited by
mitochondrial dysfunction and critical in determining metabolic activities and detoxification capacity in plant cells.
These PP2A-B’γ regulation targets include the mitochondrial dysfunction markers ALTERNATIVE OXIDASE 1A and
sulfotransferase SOT12, ACONITASE 3, enzymes responsible for methoxylation of indole glucosinolates, and calcium-
dependent protein kinase CPK1 involved in salicylic acid signalling and plant immunity. In the regulatory network,
SOT12 activity can form a positive feedback loop that fortifies the transcriptional response. In contrast, the promoter of
PP2A-B’γ is transiently inactivated by mitochondrial dysfunction signals. Hence, PP2A-B’γ does not prevent stress
responses under environmental challenges. Rather, PP2A-B’γ is essential as a post-translational regulator that prevents
unnecessary stress reactions and restores growth and development upon stress relief.
Cysteine-rich receptor-like kinase 2 coordinates abiotic and biotic stress
responses
Michael Wrzaczek
Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Finland
The receptor-like protein kinases (RLKs) are largely responsible for communication between cells and the extracellular
environment, and reactive oxygen species (ROS) production is a frequent result of RLK signaling in a multitude of
cellular processes (Kimura et al., 2017). Cysteine-rich receptor-like kinases (CRKs), a subgroup of RLKs, are defined
by a conserved pattern of cysteines in their extracellular domain and are intriguing components in ROS signaling
(Wrzaczek et al., 2010; Bourdais et al., 2015). However, they are unlikely direct ROS sensors based on the structure of
their extracellular region (Vaattovaara et al., 2019). We have identified CRK2 as essential signaling hub which can
phosphorylate and activate plasma membrane-localized NADPH oxidases (RBOH) in a calcium-independent manner
(Kimura et al., 2019). CRK2 forms a pre-assembled complex with RBOHD to activate ROS production in response to
signal perception. While previous research has concentrated on the N-terminal extension of RBOH proteins for the
regulation of their activity, the C-terminus is also a target for protein kinases during the regulation of extracellular ROS
production. Intriguingly, CRK2 also interacts with a number of different proteins to modulate callose deposition and
vesicle traffic in response to biotic and abiotic stimuli (Hunter et al., 2019). Most genomes of higher plants encode a
large number of CRK genes; however, different expansions subtypes of CRKs render translation of results to crop
species challenging. A combination of physiological, biochemical and evolutionary/genomic approaches using the
CRKs will pave the way for future understanding of large protein families in plants.
Phloem development at the single-cell resolution
Pawel Roszak1, Jung-ok Heo1,2, Bernhard Blob1, Yka Helariutta1,2
1The Sainsbury Laboratory, University of Cambridge, Cambridge, UK 2Institute of Biotechnology, HiLIFE/Organismal and Evolutionary Biology Research Programme, Faculty of Biological
and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
In the root apical meristem, stem cells and their daughter cells undergo a series of divisions that directly contribute to
the continuous apical growth of this organ. Additionally, some meristematic cells, like cells of the outer ring of
vasculature, undergo periclinal cell divisions that cause cell lineage bifurcations and hence promote the radial growth.
Two periclinal divisions in the phloem cell lineage separate metaphloem sieve element and procambial cell file from
the protophloem sieve element (PSE), which undergoes terminal differentiation only 20 cells away from the stem cell.
Using live-cell imaging, we have tracked behaviour of the PSE cells from the proliferation phase until differentiation
which culminates in the loss of the cell nucleus. Furthermore, we have obtained >700 single-cell transcriptomes, where
each of them represents a snapshot of the genetic program underlying ~90 hours-long process of PSE development.
While the proliferative stage shows very few PSE specific factors, onset of differentiation correlates with a strong
increase in number of cell type specific genes. Detailed analysis of the gene expression and modelling of the gene
regulatory network revealed important role of the well-known transcription factors as well as helped to identify new,
previously uncharacterised players.
Improving H2 photoproduction – lessons learned from photosynthesis
research
Martina Jokel, Valéria Nagy, Sergey Kosourov and Yagut Allahverdiyeva
Molecular Plant Biology, University of Turku, Tykistökatu 6 A 6th floor, FI-20520 Turku, Finland
One of the current global challenges is the development of renewable and sustainable biofuels to cover the future energy
supply. Biohydrogen, produced by photosynthetic microorganisms, has the potential to become one of the fuels of the
future, since it provides energy without CO2 emission. The green alga Chlamydomonas reinhardtii has the capability to
produce hydrogen, as a result from one of the alternative electron pathways that protects photosynthesis against excess
electron pressure. Key players of alternative electron pathways include flavodiiron proteins (FDPs) A and B,
protongradient-regulation 5 (PGR5), PGR5-like protein 1 (PGRL1) and the [FeFe]-hydrogenases. We showed that the
C. reinhardtii FDPs play an important role creating a faster acclimation to sulfur deprivation1. This condition causes
anaerobiosis in the culture and results in hydrogen production. In order to understand the regulation of photosynthesis
under fast changes of light intensity and to possibly improve the hydrogen production capacity of C. reinhardtii, the
regulation of PGRL1, PGR5, and FDPs is dissected here in more detail. We could show that under oxic conditions FDPs
function as a strong and rapid electron sink downstream of PSI. The FDP-mediated pathway operates faster than the
pathways mediated by PGRL1 and PGR52.The focus of this study lies on the interplay between several alternative
electron transfer pathways in order to understand their regulation and to identify the possible bottlenecks in paving the
way towards commercially profitable hydrogen production in C. reinhardtii. FDPs use electrons downstream of the
photosynthetic electron transport chain to reduce O2 to H2O, which is the same location hydrogenases in the electron
transport network. This creates a possible competition between the two enzymes for electrons stemming from
photosynthesis. Indeed, the deletion of FDPs resulted in a further enhancement of H2 production. Additionally, the lack
of FDPs in the flv deletion mutant lead to a more effective obstruction of carbon fixation than in wt even under elongated
light pulses. We could show that the rather simple adjustment of cultivation conditions together with the genetic
manipulation of alternative electron pathways of photosynthesis resulted in the efficient redirection of electrons towards
H2 production. Furthermore, the cultures remain viable during the pulse illumination protocol which is in contrast to
traditional nutrient deprivation protocols and makes fast recycling of the culture between growth and H2 production
possible. 1 Jokel M, Kosourov S, Battchikova N, Tsygankov AA, Aro EM and Allahverdiyeva Y. (2015) Chlamydomonas
Flavodiiron Proteins Facilitate Acclimation to Anoxia during Sulfur Deprivation. Plant Cell Physiol, 56(8):1598-607. 2 Jokel M, Johnson X, Peltier G, Aro EM and Allahverdiyeva Y. (2018) Hunting the main player enabling
Chlamydomonas reinhardtii growth under fluctuating light. Plant J, 94:822–835.
FT paralogs control the annual growth cycle and latitudinal adaptation in
Aspen trees
Ove Nilsson
Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural
Sciences (SLU), Umeå, Sweden
Day length controls flowering time in many plants. The day-length signal is perceived in the leaf, and this signal is
transduced to the shoot apex where floral initiation occurs. In Arabidopsis, the day-length response depends on the
induction of the FLOWERING LOCUS T (FT) gene by the gene CONSTANS (CO).
In Populus trees there are two FT-like paralogs called PtFT1 and PtFT2. We have shown that these genes appear to be
involved in both the control of tree flowering and in the short day-induced growth cessation and bud set occurring in
the fall. We have extended this work to show that the two FT paralogs are not only controlling the length of the growing
season by affecting the timing of bud set, but also control the timing of bud flush in the spring, thereby controlling both
the entry into, and exit out of, winter dormancy. Regulators of FT expression are also important for controlling how
quickly the trees enter dormancy in the fall. We can also show that variation in these genes are strongly associated with
local adaptation to growth at different latitudes in Swedish Aspen trees. This work adds to previous work by us and
others showing how duplication and subfunctionalization of FT genes have been important in controlling different
aspects of the regulation of plant growth and development in response to environmental signals.
Plastoquinone, state transition and gene expression
Esa Tyystjärvi
University of Turku, Department of Biochemistry / Molecular Plant Biology, 20014 Turku, Finland
The plastoquinone (PQ) pool mediates electron transfer from Photosystem II (PSII) to the cytochrome b6/f complex in
photosynthesis. The redox state of the PQ pool is known to regulate state transitions in which part of light-harvesting
complex II (LHCII) becomes phosphorylated and moves to serve Photosystem I (PSI) when the spectral distribution of
incident light favors PSII. The opposite occurs in PSI light. Furthermore, the redox state of the PQ pool has been found
to regulate the expression of both nuclear and chloroplast genes. However, the results of several different published
gene expression measurements show virtually zero overlap. An important reason for the discrepancies is that the actual
redox state of the PQ pool has rarely been measured. Our measurements of the action spectrum of the redox state of the
PQ pool made it possible both to measure and to adjust the redox state of the PQ pool using photosynthetically active
light of moderate intensity. The measurements revealed that the relationship between the redox state of the PQ pool and
the light state is curvilinear in such way that State 2 occurs at a modest reduction of the PQ pool. The most interesting
finding from our gene expression studies in plants is that several genes coding subunits of NADH:quinone
oxidoreductases functioning in both the chloroplast (NDH complex) and mitochondria (Complex I) depend strongly on
the redox state of the PQ pool. We have recently also found, using a new method developed for the measurement of the
redox state of the PQ pool of cyanobacteria, that the PQ pool of Synechocystis sp. PCC 6803 behaves in strong light and
in far red light very similarly as that of plant chloroplasts.
The mechanics of invaginations and outgrowths in plant cells
Ryan Christopher Eng, René Schneider, and Arun Sampathkumar
Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
All plant cells are surrounded by cell walls that act as a key player in controlling where a cell expands and where its
contour remains static. In many plants, the epidermal cells of cotelydons show a rich variety in shapes, e.g. in
Arabidopsis where cells form an alternating interlocked pattern of invaginations and outgrowths, reminiscent of jig-saw
puzzle pieces. Despite attracting much attention as a model system for plant morphogenesis, the precise orchestration
of molecular and cell biological events leading to highly complex cell shapes in cotelydons are still less well understood.
We used long-term live-cell imaging along with genetically encoded microtubule and cellulose synthase markers to
track the morphogenesis of individual cells in growing cotyledons. We further utilized mutants lacking the MT-
regulators, KATANIN, and CLASP as well as cellulose synthesis related mutants to test how spatial coordination of
microtubules and cellulose synthesis modulates cell shape. Our approach offers unprecedented data quality on which
hypotheses regulating cellular morphogenesis can be developed and tested.
What causes altered shoot growth in Arabidopsis hybrids?
Katelyn Sageman-Furnas1, Markus Nurmi1, Dema Alhajturki1, Lisa Smith2, Arun Sampathkumar1 and Roosa Laitinen1
1Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany 2University of Sheffield, Sheffield, UK
Hybrids occasionally exhibit phenotypes different from their parents. These phenotypes can be beneficial or
disadvantageous for plant development and often depend on environmental conditions. We are investigating two
different F1 hybrids in Arabidopsis thaliana which both exhibit altered shoot architecture in comparison to their parents.
In the F1 hybrid between Shahdara and Lagodechi 2-2 accessions, reduced stem growth and increased shoot number
come along with ectopic growth of cells on leaf petioles. The outgrowth formation is influenced by mechanical and
osmotic stress and start to appear just before flowering. This hybrid phenotype is caused by allelic interaction of
OUTGROWTH ASSOCIATED KINASE (OAK) gene. In the F1 hybrids between BG-5 and Krotzenburg-0 accessions,
the main shoot growth arrests after second internode formation and the side shoots grow longer than the main shoot.
This phenotype depends on temperature and light availability. Interaction between two loci, one on chromosome 2 and
one on chromosome 3 is required for the phenotype. Grafting experiments, hormone measurements and gene expression
analysis have provided insights of the hormonal interplay associated with the hybrid phenotype. These studies enhance
our understanding on genetic, molecular and environmental interactions directing shoot architecture in A. thaliana.
Developmental patterning of head-like inflorescences in Asteraceae
Teng Zhang1, Mikolaj Cieslak2, Feng Wang1, Suvi K. Broholm1, Teemu H. Teeri1, Przemyslaw Prusinkiewicz2, Paula
Elomaa1
1Department of Agricultural Science, Viikki Plant Science Centre, University of Helsinki, Finland 2University of Calgary, Canada
The key question in biology is how organisms generate reproducible patterns in a highly precise manner. In plants, the
regularity is visible in the architecture of inflorescences that may vary from a single flower to large flower clusters, and
is thus one of the major determinants of crop yield and reproductive success of plants. The unique feature in the large
Asteraceae plant family is that their inflorescence forms a pseudanthium, or a false flower. While the inflorescence
superficially mimics a solitary flower, it is actually composed of multiple morphologically and structurally distinct types
of flowers packed into a single head-like structure. Intriguingly, the individual flowers emerge in regular, left and right
winding spirals (parastichies), whose number follow the two consecutive numbers in a mathematical Fibonacci series
(1, 1, 2, 3, 5, 8, 13 …). We have resolved the growth dynamics of flower heads in a model plant Gerbera hybrida using
scanning electron microscopy and micro-CT imaging. Our data indicates that the phyllotactic pattern is templated by
involucral bracts initiated at the rim of the meristem during early development. The pattern is driven by expansion of
the meristem, and simultaneous emergence of multiple new primordia that quickly leads to high Fibonacci numbers.
Transgenic gerbera lines expressing the DR5 reporter indicate a major role for auxin in defining the positions of
emerging flower primordia. The experimental data has been integrated into a computational model to demonstrate how
phyllotactic patterning is established in Asteraceae flower heads.
Future proofing plant productivity by engineering leaf photosynthetic carbon
metabolism to future proof
Christine Raines
University of Essex, UK
The primary determinant of crop yield is the cumulative rate of photosynthesis over the growing season which is the
result of the crop’s ability to capture light, the efficiency by which this light is converted to biomass and how much
biomass is converted into the usable product. Traditional breeding and agronomic approaches have maximised light
capture and conversion of biomass to end products and therefore, in order to increase yield, the efficiency of energy
conversion will have to be improved. In plants that fix atmospheric CO2 using the Calvin cycle enzyme ribulose-1,5-
bisphosphate carboxylase (C3 plants) the theoretical maximum energy conversion efficiency attainable is 4.6%, but in
the field efficiencies of less than 50% of this are normal, much of this due to photorespiratory losses. However, as CO2
levels increase the limitation to the C3 cycle will shift to the regeneration of RuBP. There is now compelling evidence
from transgenic studies that manipulation of enzymes in the regenerative phase of the C3 cycle will contribute to closing
this gap in efficiency and that this can result in an increase in yield. We have used the knowledge gained from empirical
and in silico modelling to produce plants with altered combinations of proteins and enzymes to enhance leaf
photosynthetic carbon assimilation and contributing to the future proofing of plant productivity. Our approaches to the
production and the results from analysis of these plants will be presented.
Integration of hormonal and transcriptional control during vascular
development
Ykä Helariutta
Sainsbury Laboratory, Cambridge University, Bateman Street, Cambridge CB2 1LR, UK
Vascular plants have a long-distance transport system consisting of two tissue types, phloem and xylem. During root
primary development, xylem is specified early as an axis of vessel element cell files, whereas phloem is established
through a set of asymmetric cell divisions also contributing to the intervening procambial tissue (Mähönen et al. 2000
Genes Dev). We have recently been able to determinate how the key hormonal (auxin, cytokinins) and transcriptional
cues (class III HD-ZIP genes, PEAR genes) are integrated to specify the primary vascular pattern (Miyashima et al.,
2019). This highlights early phloem as an important organizer. Subsequently, we are investigating the interaction of
phloem with the flanking vascular tissues at a single-cell resolution.
Key Words: Vascular patterning, transcription factors, phloem, auxin, cytokinin
Abstracts
Poster presentations
1. Regulation of CO2-induced stomatal movements by HT1/MPK12 module
Aasumets, K., Yeh, C-Y., Tõldsepp, K., Gerhold, J. M., Wang, Y-S., Kollist, H.
University of Tartu, Institute of Technology, Tartu, Estonia
Reduced CO2 levels in the leaf indicate a shortage of photosynthetic substrate and trigger stomatal opening, while above-
ambient CO2 leads to stomatal closure. Activation of the guard cell anion channel SLAC1 is required for CO2-induced
stomatal closure, whereas stomatal opening is driven by activation of proton pumping by the plasma membrane
H+ATPase OST2/AHA1. Upstream mediators of CO2-induced stomatal movements involve carbonic anhydrases that
catalyze the conversion of CO2 into HCO3-, which in turn triggers intracellular signaling. We have shown that the RAF-
like protein kinase HT1 and MAP kinases MPK12 and MPK4 are central to guard cell CO2 signaling as plant lines with
mutated HT1, and lines lacking MPK12 and carrying silenced MPK4 in guard cells display completely abolished CO2-
induced stomatal movements. We further clarified that the activities of MPK4 and MPK12 are not directly modulated
by HCO3- in vitro, suggesting that they themselves are not directly sensing CO2/ HCO3-. We have shown that HT1 can
inhibit SLAC1 activation by OST1 and GHR1, whereas addition of MPK12 restored SLAC1 activation by inhibiting
HT1 activity. However, what the mechanism is by which MPK12/4 inhibit HT1 and how HT1 is modulating stomatal
closure and opening requires further research. Here we are using new mutant alleles of HT1 and biochemical approaches
to clarify the role of HT1 in controlling stomatal closure through activation of SLAC1 as well as for stomatal opening
through controlling the activity of guard cell H+ATPase OST2/AHA1.
2. Diurnal and within-tree variation in the chlorophyll fluorescence kinetics
of Silver birch (Betula pendula Roth) in Finland.
Olusegun Akinyemi
Czech University of Life Sciences Prague & University of Eastern Finland
The spatial and diurnal variation in the chlorophyll fluorescence kinetics and pigmentsof Betula pendula were described.
Betula pendula genotypes K1 (Kittilä - northern provenance - 67°44′N, 24°50′E) and V14 (Vehmersalmi - central
provenance - 62°45′N, 28°10′E) at the Joensuu common garden (62°36.1′N, 29°43.4’E) were used. OJIP method was
used to study important photosynthesis related chlorophyll fluorescence parameters; Fv/Fm (maximum quantum yield
of primary photochemistry for a dark-adapted leaf), Psi_o (Probability that a photon trapped by the PSII reaction center
will enter the electron transport chain) and I-P phase (efficiency of reducing final acceptors beyond PSI). Genotypes K1
and V14 showed diurnal variation in Fv/Fm and Psi_o. For both genotypes, Fv/Fm values were higher at dawn and
night but lowest at midday. Midday depression of Fv/Fm and its complete recovery, suggests that leaves dissipate
excessive light energy at midday through a non-photochemical mechanism. Variation of Fv/Fm values shows diurnal
modifications towards acclimating to changes in environmental conditions. No diurnal variation was observed for
flavonoids and chlorophyll contents. Result shows variation within a Betula pendula tree in relation to tree height but
none relating to the cardinal sides of the tree. Higher flavonoids and chlorophyll content indices were observed with
increasing light and tree height. Top leaves had lower Fv/Fm values compared to the bottom leaves, possibly because
top leaves possess a reduced electron trapping capacity. The interaction of flavonoids with chlorophyll and Fv/Fm could
be related to the effects of light intensity and increased temperature across the growing season.
3. Growth under high light and elevated temperature affect metabolic
responses and accumulation of health-promoting metabolites in kale
varieties
Sara Alegre1, Jesús Pascual Vázquez 1, Andrea Trotta1, Peter J. Gollan1, Wei Yang 2, Baoru Yang2, Eva-Mari Aro1,
Meike Burow3 and Saijaliisa Kangasjärvi1
1Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20014, Turku, Finland. 2Food Chemistry and Food Development, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland 3DynaMo Center, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen,
Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
Plants are highly sensitive to changes in their growth conditions and respond to environmental cues by coordinated
adjustments in gene expression and metabolism. Here we assessed how long-term growth under high irradiance and
elevated temperature, a scenario increasingly associated with the climate change, affects foliar chemical composition of
Brassicaceous plants. Transcript profiling of Arabidopsis suggested up-regulation of phenylpropanoid metabolism and
down-regulation of processes related to biotic stress resistance and indole glucosinolates (GSL). These observations
prompted metabolite profiling of purple (Black Magic) and pale green (Half Tall) varieties of kale, an economically
important crop species. Long-term acclimation to high light and elevated temperature resulted in reduced levels of 4-
methoxy-indol-3-yl-methyl GSL in both kale varieties. The total levels of aliphatic GSLs increased under these
conditions, although the profiles of individual GSL structures showed cultivar-dependent differences. Black Magic
became rich in 4-methylsulfinylbutyl GSL and 2-phenylethyl GSL, which have health-promoting effects in human diet.
Additionally, the purple pigmentation of Black Magic became intensified due to increased accumulation anthocyanins,
especially derivatives of cyanidin. These findings demonstrate that the potentially stressful combination of high light
and elevated temperature can have beneficial effects on the accumulation of health-promoting metabolites in leafy
vegetables.
4. Thylakoid protein phosphorylation dynamics in wild type and stn8 mutant
of the moss Physcomitrella patens
Azfar Ali Bajwa1, Caterina Gerotto1, Andrea Trotta1, Ilaria Mancini1, Tomas Morosinotto2, Eva-Mari Aro1
1. Dept. of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland; 2. Dept. of Biology, University of Padova, 35121 Padova, Italy.
In all eukaryotes protein phosphorylation is a key regulatory mechanism in several cellular processes, including the
acclimation of photosynthesis to environmental cues. Despite being a well conserved regulatory mechanism in
chloroplasts of land plants, distinct differences in thylakoid protein phosphorylation patterns have emerged from studies
on species representing different phylogenetic groups. We analyzed here the thylakoid protein phosphorylation in
Physcomitrella patens, assessing the thylakoid phospho-protein profile and dynamics in response to changes in white
light intensity. Parallel characterization of P. patens wild-type and the STN8 kinase depleted mutant (stn8 KO), in
comparison with Arabidopsis thaliana, disclosed a moss-specific pattern of thylakoid protein phosphorylation, both with
respect to the specific targets and to their dynamic phosphorylation in response to environmental cues. Noteworthy,
contrasting to vascular plants, (i) the D1 protein phosphorylation in P. patens was negligible in all light conditions, (ii)
the phosphorylation of the PSII core subunits CP43 and D2 showed only minor changes upon fluctuations in light
intensity, and (iii) the absence of the STN8 kinase completely abolished all PSII core protein phosphorylation. Further,
we detected a light-induced phosphorylation occurring in the minor antenna LHCB6, which was dependent on the STN8
kinase activity. Data presented here provide further insights into the appearance and physiological role of thylakoid
protein phosphorylation during evolution of plants harboring the oxygen evolving photosynthesis apparatus.
5. Exploring the evolution of photosynthetic machinery: Reversible thylakoid
protein phosphorylation in the moss Physcomitrella patens
Caterina Gerotto1, Andrea Trotta1, Azfar Ali Bajwa1, Ilaria Mancini1, Tomas Morosinotto2, Eva-Mari Aro1,*
1 Dept. of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland 2 Dept. of Biology, University of Padova, 35121 Padova, Italy
In all eukaryotes protein phosphorylation is a key regulatory mechanism in several cellular processes, including the
acclimation of photosynthesis to environmental cues. Despite being a well conserved regulatory mechanism in
chloroplasts of land plants, distinct differences in thylakoid protein phosphorylation patterns have emerged from studies
on species representing different phylogenetic groups. We analyzed here the thylakoid protein phosphorylation in
Physcomitrella patens, assessing the thylakoid phospho-protein profile and dynamics in response to changes in white
light intensity. Parallel characterization of P. patens wild-type and the STN8 kinase depleted mutant (stn8 KO), in
comparison with Arabidopsis thaliana, disclosed a moss-specific pattern of thylakoid protein phosphorylation, both
with respect to the specific targets and to their dynamic phosphorylation in response to environmental cues. Noteworthy,
contrasting to vascular plants, (i) the D1 protein phosphorylation in P. patens was negligible in all light conditions, (ii)
the phosphorylation of the PSII core subunits CP43 and D2 showed only minor changes upon fluctuations in light
intensity, and (iii) the absence of the STN8 kinase completely abolished all PSII core protein phosphorylation. Further,
we detected a light-induced phosphorylation occurring in the minor antenna LHCB6, which was dependent on the STN8
kinase activity. Data presented here provide further insights into the appearance and physiological role of thylakoid
protein phosphorylation during evolution of plants harboring the oxygen evolving photosynthesis apparatus.
6. Changes in the (phospho)proteome pattern in Synechocystis 6803 caused
by the elimination of SpkG kinase
Natalia Battchikova1, MartinaAngeleri1, Anna Zorina2, Eva-Mari Aro1
1 Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland 2 Institute of Plant Physiology, Russian Academy of Sciences, Laboratory of Intracellular Regulation, Botanicheskaya
Street 35, 127276, Moscow, Russia
Reversible S/T/Y protein phosphorylation plays the important role in regulation of most vital aspects of cell function,
like cell growth, division and differentiation, have been shown to occur in both eukaryotes and prokaryotes, including
cyanobacteria [1]. However, the management of cyanobacterial S/T/Y phosphoproteins by particular S/T protein kinases
/ protein phosphatases remains largely unknown. Earlier we have shown that the SpkG S/T protein kinase of
Synechocystis 6803 was responsible for phosphorylation of the electron carrier Ferredoxin 5 on T18 and T72 residues
[2]. To get more insights into a biological role of SpkG kinase, we compared protein and phosphopeptide patterns of
Synechocystis 6803 WT and SpkG mutant [3] using quantitative label-free proteomic approaches. The proteins affected
by elimination of SpkG participate in various functions. Proteins involved in ion transport, assimilation of nutrients,
formation of the EPS layer and pilins constitute the largest down-regulated group. At the level of protein
phosphorylation, results revealed a puzzling response of the (phospho)proteome of Synechocystis 6803 cells to the
elimination of SpkG. While phosphorylation of Fd5 and few other proteins indeed significantly decreased in the mutant,
we observed, in contrast, an increase in phosphorylation levels of many other proteins including ones participating in
light harvesting, photosynthesis and photosynthesis-related processes. AFVtGGAAR of allophycocyanin α-subunit was
the most up-regulated phosphopeptide in the SpkG mutant. This indicates existence of a complicated network of
cyanobacterial phosphoproteins and S/T/Y protein kinases in cyanobacteria. We complemented the SpkG mutation with
the functional copy of SpkG and are in the process of its characterization. Further, we are creating double mutants of
SpkG with SpkA-F,J-L to get further insights into the network of S/T/Y protein kinases, its regulation and signal
transduction mechanisms, which remain nearly completely unknown in cyanobacteria.
References: [1] Angeleri et al (2016) J Proteome Res 15, 4638-4652. [2] Angeleri et al (2018) FEBS Lett 592, 411-421.
[3] Zorina et al (2011) DNA Res. 18, 137-151
7. Taphrina as Model Phytopathogenic Yeast Infecting Arabidopsis
M Christita1,2, E Karjalainen1, K Wang1, J Salojärvi1,3, K Overmyer1
1 Viikki Plant Science Centre and Organismal and Evolutionary Biology Research Program, Faculty of Biological and
Environmental Sciences, University of Helsinki, Finland 2 Environment and Forestry Research and Development Institute of Manado, Indonesia 3Population Genomics and System Biology, School of Biological Sciences, Nanyang Technological University,
60 Nanyang Drive, SBS-01n-21, Singapore 637551, Singapore
Yeasts are important plant associated microbes, which can act as pathogens or beneficial symbionts that promote growth
and immunity. Immune receptors responsible for detecting yeasts and inducing immunity remain unknown. Taphrina
spp. are dimorphic, have a dual “opportunistic” lifestyle growing as yeasts in the phylloplane, but invading and infecting
plant tissues in hyphal form when conditions are favorable, and produce hormones causing tumors and leaf
deformations. We have developed a model system for studying Taphrina interactions with the genetic model plant
Arabidopsis, with a focus on leaf deformations, Taphrina’s opportunistic lifestyle, and the discovery of candidate yeast
MAMP (microbe-associated molecular pattern) receptors. We present work with an Arabidopsis associated Taphrina
strain has been designated as strain M11 and is most similar to Taphrina tormetillae, which is pathogenic on an
herbaceous plant host. Results show that inoculation of wild type Arabidopsis with Taphrina spp caused varied levels
of hypersensitive cell death response, as investigated using trypan blue staining. Arabidopsis treated with Taphrina
strain M11 showed leaf curling symptoms, which had similarity to leaf deformation symptoms associated with diseases
caused by other Taphrina spp. The activation of auxin and cytokinin responses in planta was monitored using GUS
staining with artificial hormone-responsive promoter::reporter lines. We established both forward and reverse genetic
screens mutants, which identified mutants insensitive to growth inhibition by yeast MAMPs. Secondary screens indicate
some mutants exhibit enhanced disease susceptibility upon infection with M11 Taphrina.
8. Developmental expression and subcellular localisation of ironic superoxide
dismutase 1 in Arabidopsis
Petr Dvořák1, Miroslav Ovečka1, Yulia Krasylenko1, Jozef Šamaj1, Tomáš Takáč1
1Department of Cell Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty
of Science, Palacký University Olomouc, Czech Republic
Superoxide dismutases (SODs) are key antioxidant enzymes responsible for the deactivation of superoxide radical by
catalysing its dismutation to hydrogen peroxide and oxygen. It is known that SODs determine plant abiotic stress
tolerance, but the knowledge about their in vivo developmental expression and in vivo subcellular localisation is still
elusive. Here we address the organ- and tissue- specific developmental expression patterns, as well as subcellular
localisation of ironic SOD FSD1 using modern fluorescence microscopy methods in Arabidopsis. Therefore, we stably
expressed FSD1 fused to GFP from both N- and C- termini in fsd1 mutant background under its own native promotor.
In roots, both C- and N- terminal GFP fusions of FSD1 showed high fluorescence intensity in root initials, epidermis,
columella and lateral root cap. We also observed an intense signal in aboveground organs, namely cotyledons,
hypocotyls and petioles. Notably, FSD1 was specifically accumulated in lateral root primordia corroborating the fact
that fsd1 mutants exhibit reduced number of lateral roots. At the subcellular level, the FSD1-GFP construct localized to
plastids, nuclei and cytoplasm.
This work was supported by the Czech Science Foundation GACR, grant Nr. 19-00598S.
9. SNF1-related protein kinases mediate stress responses in Arabidopsis
Juan de Dios Barajas-Lopez1, Arjun Tiwari1, Jesús Pascual Vázquez 1, Matleena Punkkinen1, Konstantin Denessiouk2,
Joanna C. Bakowska3, Teun Munnik4, Jose M. Pardo5, Hiroaki Fujii1
1Molecular Plant Biology Unit, Department of Biochemistry, University of Turku, Finland
2Faculty of Science and Engineering, Åbo Akademi University, Finland 3Department of Molecular Pharmacology and Therapeutics, Loyola University Chicago, USA 4Section Plant Cell Biology, University of Amsterdam, Netherlands 5Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas, Spain
To respond to environmental changes promptly, plants must regulate their signalling pathways precisely. Since Sucrose
Non-Fermenting 1 (SNF1)-related protein kinases (SnRKs) are important for plant growth and stress responses, we
analysed their regulation mechanisms. This family has three clades: SnRK1, SnRK2, and SnRK3. SnRK1s, which are
central kinases in sugar/energy sensing, are phosphorylated by Geminivirus Rep-Interacting Kinases (GRIKs). We
showed that GRIKs were also involved in salt stress responses, in which SnRK3s play important roles. SnRK2 are
essential kinases in abiotic stress responses, including responses to abscisic acid (ABA). We analyzed putative gamma
subunits of the SnRK family as potential regulators of SnRK2s. One of them, KING1 bound to SnRK2.6. In vitro kinase
assay showed that a recombinant KING1 modified the activity of SnRK2s. Phenotype of mutant plants lacking KING1
suggested that KING1 negatively regulates the SnRK2 function. There results indicate that there are complex networks
among stress signaling and energy status. We also identified a chemical capable of activating SnRK2.6, which will be
useful to dissect complex pathways. One of the responses that these signals induce is gene expression. One of the stress
responsive gene, ERD7 and its involvement in modification of membrane components will be also discussed.
10. Systemic signaling in the regulation of stomatal conductance in trees
Sanna Ehonen1,2, Teemu Hölttä2 and Jaakko Kangasjärvi1
1Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, and
Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland 2Institute for Atmospheric and Earth System Research / Forest Sciences, Faculty of Agriculture and Forestry, University
of Helsinki, Helsinki, Finland
Stomata play a key role in plants ability to adjust to changing environmental conditions, such as drought and heat. While
physiological and ecological studies have often considered stomata as independent units responding to local changes,
very little is known about the role of systemic signaling in the control of stomatal aperture due to changes in the aerial
environment. The aim of this study is to understand how systemic signaling is involved in rapid stomatal closure in
trees. I have set up a system where it is possible to apply different environmental conditions on local and distal leaves
separately while simultaneously monitoring rapid changes in stomatal conductance and photosynthesis. I have evidence
that stomatal closure in response to different local factors, such as rapid increase in CO2 concentration or sudden
darkness, can initiate rapid closure of stomata also in distal untreated tissues. Results from two different tree species,
Betula pendula and Populus tremula x tremuloides, as well as Arabidopsis, also suggest that the importance of systemic
signaling varies between species.
11. Systems biology of responses to simultaneous copper and iron deficiency
in Arabidopsis
Antoni Garcia-Molina, Giada Marino, Martin Lehmann and Dario Leister
Department of Botany I. Ludwig-Maximilians Universität München. Munich, Germany
Copper (Cu) and iron (Fe) are essential micronutrients for plant growth, but are often simultaneously limited in soils. In
this work, we characterised the responses of Arabidopsis thaliana plants deprived of Cu (-Cu), Fe (-Fe) or both (-Cu-
Fe) at the level of plant development, mineral composition, and reconfiguration of transcriptomes, proteomes and
metabolomes. While -Cu has only mild effects, -Cu-Fe leads to a distinct change in the microelement content of leaves,
characterised by enhanced Mn and Zn levels. Biological functions related to general stress responses, protein biology
and photosynthesis are altered under both -Fe and -Cu-Fe, though responses to each deficiency differ in detail. Proteome
responses to -Fe and -Cu-Fe generally correlate with changes in transcript amounts. Central carbon metabolites decrease
under -Fe, and especially under -Cu-Fe conditions; in particular, photosynthates decrease, whereas the pool of free
amino acids increases. Conditional networking analysis indicates that -Cu-Fe induces a switch from autotrophy to
heterotrophy, involving as key factors central mediators associated with general stress responses, photosynthesis and
protein homeostasis, as well as the metabolite fumaric acid. Our results demonstrate that the mechanisms involved in
acclimation to -Cu-Fe differ from those triggered by single deficiencies, and identify key components of acclimation.
12. Using the nuclear transcriptional co-regulator RCD1, to find PARylated
& PAR-related proteins
Richard Gossens1, Alexey Shapiguzov2, Jaakko Kangasjärvi3
1 University of Helsinki Faculty of Biological and Environmental Sciences, Organismal and Evolutionary Biology
Research Programme; University of Helsinki, Viikki Plant Science Center, Helsinki, Finland
The posttranslational modification poly-ADP-ribose (PAR) is a transient modification of proteins, which is linked with
chromatin remodeling programmed cell death amongst others. This transient chain of APD-ribose monomers is
synthesized by poly-ADP-ribose polymerases. Recently, some mysteries about PARylated proteins have been solved in
the animal field. In plants, however, many mechanisms about PARylation and PARylated proteins and the functioning
thereof have remained in the dark. This work aims to characterize in vivo proteins that have undergone addition of PAR
and study the functional aspect of this event. Extraction and enrichment of PAR are performed using the two domains
responsible for PAR-binding of RCD1, the WWE- and PARP-like domain. RADICAL CELL DEATH 1 (RCD1) is a
plant protein that has a strong affinity to PAR in vitro and possesses another C-terminal domain that allows it to interact
with over 30 transcription factors. As such, RCD1 has the potential to be a PAR reader, which upon PAR-binding might
change its interaction with these transcription factors. The corresponding domains of the closest homolog of RCD1,
SIMILAR TO RCD ONE 1 (SRO1), will also be employed for enrichment. After which mass spectrometry will be
performed to identify the enriched proteins, amongst which will be PARylated proteins and PAR associated proteins.
Which opens the door to study how PARylation affects its targets.
13. The unique photosynthetic apparatus of Pinaceae – Analysis of
photosynthetic complexes in Norway spruce (Picea abies)
Steffen Grebe1, Andrea Trotta1, Azfar A. Bajwa1, Marjaana Suorsa1, Peter J. Gollan1, Stefan Jansson2, Mikko Tikkanen1
and Eva-Mari Aro1
1Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland 2Umeå University, Faculty of Science and Technology, Department of Plant Physiology, Umeå Plant Science Centre
(UPSC), SE-90187 Umeå, Sweden
Members of Pinaceae have been a long time in focus of photosynthetic research, but so far no detailed description of
the protein components of the photosynthetic apparatus of these gymnosperms has been available. In this study we report
a detailed characterization of the thylakoid photosynthetic machinery of Norway spruce (Picea abies (L.) Karst) by
MS/MS identification of thylakoid proteins and in-silico analysis of LHC family members. Picea abies thylakoid
proteins were identified from two-dimensional lpBN/SDS-PAGE resulting in a 2D protein map. This 2D map allowed
the direct comparison of the photosynthetic protein complex composition with the model angiosperm Arabidopsis
thaliana. Although the subunit composition of Picea abies core PSI and PSII complexes is largely similar compared to
Arabidopsis thaliana, it harbors high amounts of a smaller PSI-subcomplex, closely resembling the assembly
intermediate PSI*.In addition, in-silico comparison of the distribution of LHC family members in Pinaceae with other
land plants revealed that Picea abies and other Pinaceae (together with Gnetaceae and Welwitschiaceae) have lost
LHCB3, LHCB6 and LHCB4, while retaining LHCB8 (formerly LHCB4.3). These findings show the composition of
the photosynthetic apparatus of Picea abies and other Pinaceae members to be unique among land plants. Additionally,
we found a low temperature induced, seasonal phosphorylation of the LHCII antenna in Picea abies. We hypothesize
that this LHCII phosphorylation could be a prerequisite for the sustained non-photochemical quenching (NPQ) observed
in Pinaceae species.
14. Photosynthetic and growth responses of Arundo donax plantlets under
different oxygen deficiency stresses and reoxygenation
Lorenzo Guglielminetti
University of Pisa, Italy
Arundo donax L. spontaneously grows in different kinds of environments with limitation to low temperature and is thus
widespread in temperate and hot areas around the world. Moreover, this perennial rhizomatous grass has been
recognized as a leading candidate crop in the Mediterranean for lignocellulosic feedstock due to its high C3
photosynthetic capacity, positive energy balance and low agroecological management demand. In this study, the
photosynthetic performance and growth response of A. donax to waterlogging and submergence stress following a time
course as well as their respective re-oxygenation were analyzed under controlled conditions. Results of growth response
showed that biomass production was strongly conditioned by the availability of oxygen. In fact, only waterlogged plants
showed similar growth capacity to those under control conditions, while plants under submergence resulted in a dramatic
reduction of this trait. The simultaneous measurements of both gas exchanges and chlorophyll fluorescence highlighted
an alteration of both stomatal and non-stomatal photosynthetic behaviors during a short/medium period of oxygen
deprivation and re-oxygenation. Photosynthetic CO2 uptake was strictly related to a combination of stomatal and
mesophyll diffusional constrains, depending on the severity of the treatment and exposure time. Conditions of
waterlogging and hypoxia revealed a slight growth plasticity of the species in response to prolonged stress conditions,
followed by a fast recovery upon reoxygenation. Moreover, the rapid restoration of physiological functions after O2
deprivation testifies to the environmental plasticity of this species, although prolonged O2 shortage proved detrimental
to A. donax by hampering growth and photosynthetic CO2 uptake.
15. Fast kinetics of PSI and PSII in the photosynthetic sea slug Elysia timida
Vesa Havurinne, Esa Tyystjärvi
University of Turku, Department of Biochemistry, Molecular plant biology, Finland
Photosynthetic sea slugs have long captured the attention of researchers and laymen alike, but the study of these animals
is hindered by the lack of continuous laboratory cultures. We have continuously grown the sea slug Elysia timida and
its feedstock, the green alga Acetabularia acetabulum, in our lab and this has allowed us to optimize novel methods to
study electron transfer kinetics of photosystems (PS) I and II in these animals. Our data show that i) energy transfer
from the antennae to PSII is slower in the sea slugs vs. the algae, but electron transfer within PSII is similar between the
two, ii) PSII photoinhibition is significantly lower in the slugs than the algae, and iii) stolen chloroplasts retain the
capacity to recover from photoinhibition of PSII. These findings suggest that PSII functionality is protected inside the
slugs, but highlight another problem that the slugs must have solved: finding a safe depository for the electrons
originating from PSII in order to avoid major ROS bursts on the PSI side of the electron transfer chain. We have shown
that flavodiiron proteins can fulfill such a role and enhance the longevity of the chloroplasts inside the slugs in specific
conditions like under fluctuating light. However, future research on photosynthetic sea slugs should focus on the main
electron sink of photosynthesis, carbon fixation, and its relation to the longevity of the chloroplasts inside these
remarkable animals.
16. Harnessing the versatile Ubiquitin signals to combat plant pathogens
Kristiina Himanen
Organismal and Evolutionary Biology Research Programme, University of Helsinki, Finland
Ubiquitin signaling pathways have emerged as fast evolving regulatory pathways, in importance reaching cascades such
as phosphorylation. Ubiquitin signals are involved in targeted degradation of transcriptional activators and repressors,
as well as upstream receptors, to facilitate internal developmental switches and responses to external environmental
challenges. In addition, significant roles for Ubiquitin in chromatin modifications for transcriptional regulation have
emerged. Our research expands the knowledge base of Ubiquitin signaling by screening for novel Ubiquitin factors
during plant pathogen interactions. To allow dissecting temporal and spatial progression of the responses, image-based
assays are being established. Finally, characterization of chromatin regulating protein complexes and associated
ubiquitin codes will allow mapping the dynamically changing epigenetic landscape. Ongoing collaborations with cereal
breeders and pre-breeders facilitate testing translational potential of the molecular discoveries.
17. UV-B responses in different cultivars of quinoa: a focus on hormonal
regulation
Thais Huarancca Reyes1, Lorenzo Mariotti1, Jose Martin Ramos-Diaz2, Kirsi Jouppila2, Lorenzo Guglielminetti1
1 University of Pisa, Italy 2 University of Helsinki, Finland
Increased ultraviolet-B (UV-B) radiation due to global change can affect the development and metabolism of plants.
Quinoa (Chenopodium quinoa Willd.) is a grain crop with worldwide interest due to its high protein and well-balanced
amino acid content. Moreover, it has been reported that quinoa can grow under high salinity levels, drought and high
UV radiation. However, the physiological mechanisms behind its abiotic stress tolerance are still unclear, especially
those related to UV-B response. Our recent study revealed that quinoa regulates different mechanisms of response
depending on the UV-B irradiation dosage, in which 3 days of 3.04 kJ m-2 d-1 UV-B induces UV-B-specific signaling
to counteract reactive oxygen species and photosystem II damage, while 6.08 kJ m-2 d-1 UV-B may promote UV-B-
independent response by the induction of pathogen-defense/wound-signaling pathways. Here, we attempt to characterize
in more detail the mechanisms of quinoa in response to different UV-B doses which are still unclear. It is known that
UV-B controls plant hormones and consequently plant morphology and defense. In this line, we analyzed the hormonal
balance of different quinoa varieties in response to short acute UV-B treatments under controlled conditions, and the
results will be discussed.
18. The cysteine-rich receptor-like kinase CRK2 during stress responses in
Arabidopsis thaliana Kerri Hunter1, Sachie Kimura1, Anne Rokka2, Cuong Tran1, Masatsugu Toyota3, Jyrki Kukkonen4, Michael Wrzaczek1
1 Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Finland. 2
Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland. 3 Department of
Biochemistry and Molecular Biology, Saitama University, Saitama, Japan and Department of Botany, University of
Wisconsin-Madison, Madison, Wisconsin, USA. 4 Biochemistry and Cell Biology, Department of Veterinary
Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland and Department of Physiology,
Faculty of Medicine, University of Helsinki, Helsinki, Finland
In order to maintain health, growth, and productivity, plants must be able to adapt to increasingly variable environmental
conditions. Plants are continuously flooded with information from their surrounding environment, which must be
sensed, incorporated, and responded to accordingly. Much of the communication between plant cells and the
extracellular environment is carried out by the receptor-like protein kinases (RLKs), including the cysteine-rich
receptor-like kinase (CRK) subfamily. Despite the large size of the CRK gene family, their physiological roles and
functions on a biochemical and cellular level remain largely uncharacterized. We performed large scale phenotyping of
a crk T-DNA mutant collection in Arabidopsis thaliana (Arabidopsis), which suggested roles for the CRKs in several
developmental processes, as well as during abiotic and biotic stress responses. CRK2 emerged as an important CRK,
with several strong loss-of-function phenotypes and a notable phylogenetic position. We established that CRK2
enhances salt tolerance through the regulation of callose synthase 1 (CALS1) dependent callose deposition at
plasmodesmata. This revealed a previously uncharacterized role for callose deposition in response to high salinity. We
showed that this callose deposition has an effect on plasmodesmal permeability, and therefore a potential impact on
intercellular signalling. Additionally, CRK2 was found to regulate the formation of an unknown vesicle type during salt
stress, which could possibly be involved in cell-to-cell signalling as well. We have described how CRK2 regulates ROS
production during immunity by regulation of RBOHD via C-terminal phosphorylation. We observed highly specific
changes in the subcellular localization of CRK2 in response to various stress treatments, and demonstrated that these
localization patterns are critical for protein function and interactions. The subcellular localization and many of the
cellular functions of CRK2 were dependent on phospholipase D alpha 1 (PLDɑ1) activity, and PLDɑ1 was consistently
identified as one of the top proteins to interact with CRK2. Thus, we propose that CRK2 is a fundamental CRK, which
acts in connection with PLDɑ1 to regulate several cellular processes during the response to environmental stimuli.
19. Multiple plasma membrane aquaporins interact to modulate conductance
of carbon dioxide and water
D. Israel1, C. R. Warren2, J. J. Zwiazek3, T. M. Robson1
1 Organismal and Evolutionary Biology, University of Helsinki, Helsinki, Finland 2 School of Life and Environmental Sciences, University of Sydney, Sydney, Australia 3 Department of Renewable Resources, University of Alberta, Edmonton, Canada
Aquaporins are small proteins facilitating the passage of water and certain small molecules through the lipid bilayer.
Our focus was on plasma membrane intrinsic proteins of the PIP2 subgroup, which are known to associate with each
other to form tetramers at the membrane, but also interact with PIP1s. Our aim was to characterize the role of selected
PIP2s and their interaction in the regulation of whole-plant water relations, photosynthesis and the conductance of CO2
through the leaf. We used knockout mutants lacking one or more aquaporin, which we expected to result in an increase
in the resistance to water flow across cell membranes. This should lead to plants aiming to maintain a positive water
balance by lowering stomatal conductance, which in turn could restrict photosynthesis. However, the interaction of
aquaporins also affects their permeability and substrate specificity. Consequently, multiple knockout mutants may
behave very differently from single mutants. To test whether this was the case, we compared single, double and triple
knockout mutants with the wild type plants of Arabidopsis thaliana under standard greenhouse conditions and measured
leaf-level gas exchange. Contrary to our expectations, the absence of functional PIPs generally resulted in higher
stomatal conductance and rates of photosynthesis. Nevertheless, plants lacking only PIP2;5 differed from the double
and triple mutants deficient in other PIP2s as well. In conclusion, PIP2;5 appears to facilitate CO2 diffusion through the
leaf, but also plays a role in aquaporin interaction.
20. Outer Bark: the Final Frontier between the Plant and Environment Juha Immanen1, Juan Alonso-Serra2,3, Omid Safronov2, Sitaram Rajaraman2, Pezhman Safdari2, Jaakko Kangasjärvi2,
Yrjö Helariutta2,3,4, Teemu H. Teeri2,5, Clare J. Strachan6, Kaisa Nieminen1, Jarkko Salojärvi2,7,8
1 Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland. 2 Viikki Plant Science
Centre, University of Helsinki, Helsinki, 00014, Helsinki, Finland. 3 Institute of Biotechnology, University of Helsinki,
Helsinki, 00014, Helsinki, Finland. 4 Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK. 5
Department of Agricultural Sciences, University of Helsinki, Helsinki, 00014 Helsinki, Finland. 6 Drug Research
Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, 00014
Helsinki, Finland. 7 School of Biological Sciences, Nanyang Technological University, 637551, Singapore. 8 Singapore
Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551, Singapore.
The aim of our research is to understand the genetic basis of wood and bark development in forest trees. This knowledge
has immense applied value for forest industry: wood and bark represent massive renewable resources of lignocellulosic
biomass, with potential for conversion into timber, pulp, fuels, energy, and value-added substances. We are focusing
our forward and reverse genetic studies on silver birch (Betula pendula), an important boreal forestry tree with multiple
advantageous genetic traits.
Tissues of a tree trunk, which provide structural support and enable long-distance transport, are protected by bark, the
defensive stem-environment barrier. Bark consists of an array of tissues outwards of the vascular cambium: phloem,
phelloderm, phellogen (aka cork cambium) and phellem; the last three are collectively called periderm (aka outer bark).
Trunk tissues are produced by two lateral meristems: vascular cambium, which forms the phloem and xylem tissues,
and phellogen, which provides the periderm. Due to their defensive functions, bark tissues are enriched with diverse
secondary metabolites. To advance our understanding of wood and bark development, we performed a comprehensive
analysis of the transcriptomics and chemical composition (e.g. triterpenoids, non-cellulosic sugars) of all silver birch
trunk tissues, from the outermost phellem to the previous year’s annual xylem ring. By integrating our data, we observed
that the active metabolic pathways and chemical composition were highly diverse between the different tissues, and that
both common and specific regulatory genes were expressed in the two lateral meristems.
The identified regulatory components represent optimal targets for tree breeding and biotechnological applications.
Modern biotechnology will provide ample opportunities to develop novel wood and bark products, e.g. for medical
compounds and composite materials. Our ultimate aim is to optimize forest trees biomass production for various
valorization purposes in the future biorefineries.
21. New optimization standards for cyanobacterial pathway engineering
Pekka Patrikainen, Lauri Kakko, Eva-Mari Aro, Pauli Kallio
Molecular Plant Biology, Department of Biochemistry, University of Turku, Finland
Cyanobacteria have been recognized as potential biotechnological hosts for the direct solar-driven production of carbon-
based target chemicals from CO2. This is one of the key concepts in the recent EU project SUNRISE (Solar Energy for
Circular Economy; www.sunriseaction.com), aiming at the transition towards sustainable future industrial applications.
As part of this ambitious goal, systematic development of synthetic biology strategies has critically improved the
prospects for generating robust cyanobacterial production strains that would be applicable for process optimization and
scale-up. A key biological engineering challenge is to couple the photosynthetic light reactions, CO2 fixation and the
step-wise downstream reactions towards the target product as a functional entity. This is especially complicated for
artificial multi-gene pathways, where the expression between individual enzymes (in respect to consecutive catalytic
activities) is not in balance. This easily leads to severely disturbed pathway fluxes, metabolic imbalance and intermediate
toxicity effects, that compromise productivity. In response, we are now implementing a modular expression construct
assembly strategy that allows the optimization of multicistronic operons at the translational level. The system is based
on i) the use of a library of ribosome binding sites (RBS) alibraries of pathway variants with different translational
patterns, and iii) a high throughput screening approach to identify the best-producing clones. This may provide a generic
strategy to optimize production via recombinant pathways in photoautotrophic hosts - a concept which has not
previously been applied in cyanobacterial engineering.
22. A Molecular Framework for Sieve Pore Formation during Phloem
Development
Lothar Kalmbach1, Ykä Helariutta 1,2
1 The Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge, CB2 1LR, UK 2 Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
Plant cell walls are both rigid to resist internal pressure and highly dynamic to allow for adaptations upon environmental
or developmental cues. During vascular development, extensive modifications of the sieve element end walls give rise
to the sieve plate: a thick cell wall which is perforated with sizeable pores. These sieve plate pores originate from
plasmodesmata and symplastically connect adjacent sieve elements. They are therefore critical for symplastic bulk
transport of sugars and amino acids, but also for hormone- and RNA-mediated long-distance signaling. Although
morphological changes in the cell wall during formation of these sieve pores are well documented, the underlying
molecular and genetic factors are largely unknown. Conceptually, genes necessary for sieve pore formation should be
sieve-element-specific and encode for cell wall modifying enzymes, scaffolding plasma membrane proteins, or
homologues to known plasmodesmata proteins. We mined root transcriptional data of high spatial resolution for genes
expressed specifically during the intermediate and later stages of phloem development. Identified candidates were then
localized and screened for enriched or exclusive subcellular localization towards the sieve plates. This approach
identified two pairs of plasma membrane proteins as putative sieve pore morphogenesis factors that are now functionally
characterized for their role in pore formation through reverse genetics, co-localization and tissue-specific genetic
interference. Our understanding of key events in phloem development will then help to place sieve pore formation into
the larger context of developmental dynamics of roots.
23. Measurement of the redox state of the plastoquinone pool in
cyanobacteria
Sergey Khorobrykh1, Tatsuhiro Tsurumaki2,3, Kan Tanaka2, Taina Tyystjärvi1, Esa Tyystjärvi1
1 Department of Biochemistry/Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland 2 Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 29-R1-
4259 Nagatsuta, Yokohama 226-8503, Japan 3 Graduate School of Life Science and Technology, Tokyo Institute of Technology, 29-R1-4259 Nagatsuta, Yokohama
226-8503, Japan
A new method was developed for measurement of the redox state of the plastoquinone (PQ) pool in Synechocystis sp.
PCC6803. Cells were illuminated on a glass fiber filter, PQ was extracted with ethyl acetate and determined with HPLC.
Control samples with fully reduced and oxidized photoactive PQ pool were prepared by high and far-red light treatments,
respectively, or by blocking the photosynthetic electron transfer chemically before and after PQ in moderate light. Circa
50% of total PQ was photoactive. In standard growth conditions (constant moderate light, 32°C, ambient air) 32-45 %
of the photoactive PQ pool was reduced whereas in high CO2, only 14-18 % of the pool was reduced. In darkness, 9-22
% of the PQ pool was reduced.
24. Novel alleles of agronomically important gene Q of wheat and Aegilops
species
Irina Konopatskaia1*, Valeriya Vavilova1, Alexandr Blinov1
1 Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation [email protected]
In polyploid wheat gene Q controls a wide range of agronomically important traits including primarily the threshability
and, thus, defining the crop yield and efficiency of the harvest. Here we have studied the spike morphology and Q gene
for 15 previously uninvestigated accessions of wheat species, including four endemic species, and 24 accessions of
Aegilops species. For the endemic species Triticum aestivum ssp. petropavlovskyi and T. spelta ssp. yunnanense, the Q
gene was studied for the first time. The novel Q-5A allele with the unique insertion of 161 bp in length was described
for the accessions of T. tibetanum. We determined the variability within the q-5D genes among hexaploid wheats and
their D genome donor Aegilops tauschii. Furthermore we’ve distinguished three accessions of Ae. tauschii ssp.
strangulata, which could be involved in the origin of hexaploid wheat species. The comparative and phylogenetic
analysis of the sequences of 5A and 5D genomes’ copies of Q gene allowed us to clarify the relationships between
species of the genus Triticum and to predict the donor of the D genome among the Ae. tauschii accessions. Thus, despite
the gene Q is extensively studied, the new investigations still give insights into the evolution and domestication of wheat.
This work was supported by the Russian Science Foundation (grant number: 16-16-10021-P).
25. Role of MED25 in stomatal regulation and development in Arabidopsis
thaliana
Kaspar Koolmeister, Hanna Hõrak, Liina Jakobson and Hannes Kollist
University of Tartu, Institute of Technology, Tartu, Estonia
Stomata are small pores in plant epidermis which regulate transpiration and CO2 uptake. Stomatal closure in drought
conditions effectively decreases plant water loss and increases survival. Further understanding of plant stomatal
movements is therefore necessary for development of plants that can better cope with changing environmental
conditions. It is currently not clear whether red light induced stomatal opening is triggered by decreased intercellular
CO2 levels caused by carbon gain in photosynthesis or by a specific red light induced response. To clarify this issue, we
assessed the role of MED25, a possible regulator of stomatal red light responses, in stomatal development and regulation.
Experiments conducted with plants carrying dysfunctional MED25 and transgenic MED25 expressing lines showed that
MED25 affects stomatal opening processes in red light as well as stomatal closure in response to darkness and ABA. In
addition, we found that plants with dysfunctional MED25 have lower stomatal index, indicating a role for MED25 in
stomatal development. Results of this study will help to better understand stomatal opening and developmental
regulation in red light.
26. Sustained H2-photoproduction in green alga Chlamydomonas reinhardtii
primarily depends on the photosystem II activity
Sergey Kosourov1, Valéria Nagy1, Dmitry Shevela2, Martina Jokel1, Johannes Messinger2,3 and Yagut Allahverdiyeva1
1Molecular Plant Biology, Department of Biochemistry, University of Turku, Turku, Finland; 2Department of
Chemistry, Chemistry Biology Centre, Umeå University, Umeå, Sweden; 3Department of Chemistry, Ångström
Laboratory, Uppsala University, Uppsala, Sweden
Many species of green algae, including the model organism Chlamydomonas reinhardtii, possess the [FeFe]-
hydrogenase enzyme(s) that catalyze the reversible reduction of protons to molecular hydrogen: 2H+ + 2e- ⇔ H2 [1].
The enzyme interacts with the photosynthetic electron transport chain at the level of ferredoxin and links the water-
oxidizing reaction at photosystem II (PSII) to the reduction of protons to H2 [2]. A significant fraction of electrons for
the hydrogenase-driven reaction may also originate from the PSII-independent mechanism [3]. This mechanism depends
on the metabolic oxidation of stored organic compounds that is coupled to photosystem I (PSI) via the plastoquinone
pool. H2 photoproduction occurs in anaerobic, dark-adapted algae on illumination [4]. The process, however, is difficult
to sustain due to a high sensitivity of the [FeFe]-hydrogenase enzyme to O2 co-produced in PSII during illumination.
Recently, we developed a novel protocol for sustaining H2 photoproduction in algal cultures [5]. In this protocol, the
sustainability is achieved by a shift of growing algal cultures from continuous illumination to a train of short (1–5 s)
light pulses interrupted by longer (3–9 s) dark phases. The pulse illumination prevents activation of the Calvin-Benson-
Bassham (CBB) cycle and engages efficient distribution of photosynthetic electrons to the hydrogenase. As a result, H2
photoproduction in algal cultures could be sustained for up to 4 days. Using the membrane inlet mass spectrometry
(MIMS) and 18O-labeled water, we further proved that H2 production in pulse-illuminated algae depends primarily on
the direct water biophotolysis, where up to 96% electrons originate from water. In the case of an insufficient electron
flow from PSII (due to inhibition by DCMU or in the PSII-deficient mutants), the reductants for the hydrogenase are
provided via the PSII-independent pathway. Although a very efficient in the beginning, this pathway could not sustain
the process as long as the water oxidation at PSII centers, and H2 photoproduction in PSII-deficient algae lasts only for
a few hours. These findings prove that algae are capable to the direct and sustained water biophotolisis with simultaneous
production of H2 and O2. The efficiency of this process can be further improved via metabolic engineering and
construction of efficient algal factories.
References
[1]Ghirardi ML, Dubini A, Yu J, Maness P-C (2009) Chem. Soc. Rev. 38:52–61. [2]Volgusheva A, Styring S, Mamedov F (2013)
Proc. Natl. Acad. Sci. 110:7223–7228. [3]Gfeller RP, Gibbs M (1984) Plant Physiol. 75:212-218.
[4]Gaffron H, Rubin J (1942) J. Gen. Physiol. 26:219–240. [5]Kosourov S, Jokel M, Aro E-M, Allahverdiyeva Y (2018) Energy
Environ. Sci. 11:1431–1436.
27. Multiple signal integration - How day-length affects stress responses in
Arabidopsis
Julia Krasensky-Wrzaczek1, Dmitry Yarmolinsky2, Jesus Pascual Vazquez3, Cuong Tran1, Hannes Kollist2, Saijaliisa
Kangasjärvi3, Jaakko Kangasjärvi1
1Faculty of Biological and Environmental Sciences, University of Helsinki, Finland 2University of Tartu, Estonia 3University of Turku, Finland
Light and temperature are two main factors that enable plants to sense seasonal changes and adjust growth, defense, and
transition to flowering according to the prevailing conditions. In order to integrate the multitude of signals that plants
are exposed to, complex signaling networks have evolved. We are investigating signaling mechanisms that determine
plant stress sensitivity under different light conditions, more specifically different day-lengths. We are using ozone as a
non-invasive tool to induce apoplastic ROS production - a common cellular response to biotic as well as abiotic stresses.
Under long day (LD) growth conditions, we observed a faster and stronger activation of molecular defenses (including
protein phosphorylation cascades, and hormone signaling) as well as Programmed Cell Death (PCD) in response to
ozone, as compared to plants grown under short day (SD) conditions. We found that salicylic acid plays an important
role in activation of either protective redox-poising mechanisms or PCD in a day-length-sensitive manner. Furthermore,
we found that phytochrome-dependent signaling plays an important role in day-length-specific stress responses.
28. ABI1 PP2C regulates alternative splicing to modulate ABA response in
Arabidopsis thaliana
Sivakumar Krishnamoorthy1, Michał Szcześniak2 and Agnieszka Ludwików1
1 Department of Biotechnology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, ul,
Uniwersytetu Poznańskiego 6, 61-614 Poznań, Poland 2 Laboratory of Integrative Genomics, Institute of Anthropology, Adam Mickiewicz University, ul, Uniwersytetu ,
Poznańskiego 6, 61-614 Poznań, Poland
In Arabidopsis, the current knowledge about the molecular mechanisms underlying abscisic acid pathway (ABA)
perception and signal transduction is limited. In ABA core signaling pathway, group A protein phosphatase type
2C (PP2C) including ABI1 acts as a negative regulator of the MAP cascade MAPKKK17/18-MKK3-MPK 1/2/7/14.
This study focuses on dynamics of the contribution by alternative splicing (AS) events in response to ABA
treatment. We isolated mRNA samples in triplicates from four genotypes WT Col-0, abi1td, mkkk17, mkkk18 and
performed paired end sequencing by using Illumina platform to produce 100 M reads per sample. On an average,
95% of the reads were uniquely mapped against ab initio transcriptome with the quality phred score above 33.
The reads were preprocessed using various bioinformatics algorithms, after adapter trimming which yielded 23007
genes containing 52686 transcripts. In addition, after the gene quantification, differential expression analysis
was performed to find the significant number of genes involved. We systematically examined the global
regulatory features of splicing analysis using rMATS and results reveal that, IR event (Intron Retention) yields
higher amount of significant protein coding genes, followed by A3SS event (Alternative 3’ Splice site). “mRNA
splicing via spliceosome”, “nuclear speck”, “spliceosomal complex”, “chloroplast envelope” are the common
enriched term with regards to Gene set enrichment analysis. There is significant increase in the number of
splicing counts in knockouts, when compared to WT. Further downstream data analysis will give insights to
understand the proteome diversity involved in ABA-induced MAPKK17/18 signaling pathway.
This work has been supported by the Polish National Science Centre grant No. 2016/22/E/NZ3/00345
and POWR.03.02.00-00-I022/16
Keywords: ABA signaling, Alternative splicing, Abiotic stress, Next Generation Sequencing
29. Molecular Cues for Masting in Celmisia
Samarth Kulshrestha1, Dave Kelly1, Matthew H. Turnbull1, Richard MacKnight2, Paula E. Jameson1
1 School of Biological Sciences University of Canterbury, NZ 2 Department of Biochemistry, University of Otago, NZ
Masting is synchronised highly variable flowering by populations of perennial plants, such as Celmisia lyallii
(Asteraceae), over a wide geographical area. The ΔT model hypothesises that the size of the temperature difference
between the two preceding summers determines the current year’s flowering intensity. However, the molecular
mechanism behind the role of temperature-induced mast flowering is still unknown. In model plant species, the
flowering process is induced by the FLOWERING LOCUS T (FT) gene and regulated by various transcription factors
which are responsive to temperature and/or photoperiod. Researchers have also established microRNAs 156 and 172 as
key regulators of flowering time in response to various external cues. The current study deals with the identification of
essential flowering pathway genes that might have a role in the masting syndrome of C. lyallii (snow daisy) plants.
Transcriptomic sequencing and gene expression analysis of key floral integrator genes showed conservation of the
model flowering pathway in Celmisia. Additionally, we identified potential repressors of FT and SOC1, ANTI-
FLOWERING LOCUS T (AFT) and TERMINAL FLOWER1 (TFL1), that may control the reproductive phase transitions
in Celmisia lyallii. We also hypothesise that the summer temperatures may lead to differential regulation in the sugar
and hormonal signalling pathways repressing the expression of floral repressors leading to the initiation of flowering.
Our study allows prediction of mast flowering in the New Zealand flora to predict the explosion in the pest population
and therefore, can be used as a signal to launch appropriate conservation programs for the protection of endangered
fauna.
30. Novel regulators of stomatal closure
Marina Leal Gavarrón1, Cezary Waszczak1, Triin Vahisalu1, Maija Sierla1, Dmitry Yarmolinsky2, Olena Zamora2,
Melanie Carmody1, Hannes Kollist2 & Jaakko Kangasjärvi1.
1Faculty of Biological and Environmental Sciences, University of Helsinki, Finland. 2Institute of Technology, University of Tartu, Estonia.
A crucial response mechanism of the plants to be able to adapt to the fast changes in the environment is stomatal
aperture/closure. Stomata are epidermis pores surrounded by two symmetrical guard cells, that regulates the aperture or
closure of the pore, affecting the plant gas exchange with the environment (e.g. water evaporation, CO2 , O2,etc.,).
Guard cells respond to multiple environmental factors e.g. light/darkness cycles, CO2 levels, drought, low humidity,
pathogens and air pollutants such as ozone. Ozone is a powerful oxidant molecule that induces reactive oxygen species
(ROS) production in plants. It penetrates plants via stomata and decomposes to ROS in the apoplast, followed by a
molecular cascade signaling that leads to activate response mechanisms, e.g. stomatal closure, which makes it an
excellent tool to study stomatal regulation. Plants deficient in ozone-induced stomatal closure show leaf damage, which
allows the identification of stomatal mutants. Using ozone sensitivity as a main screening tool, Plant Stress Group, from
Helsinki University, has conducted a large-scale forward genetics screen to identify novel components in stomatal
regulation. The mutant lines identified in the screen impaired in guard cell signaling (over 50 novel mutants) may have
a defect in stomatal closure or in the composition of the cell wall in the leaf. Mapping populations have been created
from the most interesting mutant lines identified in the screen. SHOREmap results shown that the causative mutations
are in characterized proteins with no described function in the stomatal closure yet. Our goal in this project is to elucidate
the role of these proteins in the guard cell wall composition and the importance of the guard cell wall flexibility in the
stomatal closure.
31. Recovery from photosystem I inhibition in Arabidopsis thaliana
Tapio Lempiäinen, Eevi Rintamäki, Eva-Mari Aro and Mikko Tikkanen
Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland
Photosystem I (PSI) becomes inhibited in adverse environmental conditions where imbalance between light reactions
and stromal metabolism leads to the over-reduction of stromal electron acceptors. This leads to acceptor side limitation
in PSI, which can result in oxidative damage of the auxiliary iron-sulfur clusters. Loss of the iron-sulfur clusters prevents
electron transfer from PSI reaction center to stromal acceptors. PSI inhibition ultimately leads to degradation and de-
novo synthesis of the entire PSI complex. Because of this, recovery from PSI photoinhibition is a slow process and in
some plant species even irreversible. We used our newly developed photosystem I inhibition protocol to investigate the
strategies that plants use to cope with the consequences of PSI inhibition. The acclimation process to limited PSI function
was investigated in wild type Arabidopsis thaliana. Already a mild photoinhibition of PSI reduces the flux of linear
electron transfer chain under low light conditions when regulatory mechanisms, such as non-photochemical quenching
and photosynthetic control, are not activated. Stronger inhibition also delayed the activation of these mechanisms under
high light conditions. The function of stromal redox components was widely altered, which in turn resulted in changes
in the redox regulation of ATP synthase. In addition to the above-described dynamic regulatory responses, also the
amounts of ATP synthase and cytochrome b6f complex increased upon inhibition, and during recovery. This implies
that plants sense the lack of energy and try to compensate the situation by increasing the amounts of cytochrome b6f
complex and ATP synthase.
32. UVR8-mediated photoprotection in Arabidopsis thaliana
Manuela Leonardelli1, Emilie Demarsy1, Roman Ulm1
1Department of Botany and Plant Biology, University of Geneva, Switzerland
Light is central to plants. It is used not only for photosynthesis, but also for fine-tuning development and growth.
Ultraviolet-B (UV-B) radiation, which is an integral component of solar light, acts both as an environmental stress and
as an informational signal. Plants have thus developed a suite of molecular and physiological responses to UV-B
exposure. Of particular importance is the UVR8 photoreceptor, which regulates the expression of several genes involved
in the UV-B response, including some that code for chloroplast proteins. Here, we show that acclimation to low doses
of UV-B alleviates UV-B induced photodamage of the photosynthetic machinery, and that this is a UVR8 mediated
mechanism. We will present possible mechanisms linking UVR8 signalling to the photosynthetic machinery and our
current understanding of UVR8 mediated photoprotection in Arabidopsis.
33. The role of MONOPTEROS and other auxin response factors in root
secondary development
Munan Lyu1,2, Riikka Mäkilä, Tiina Blomster &Ari Pekka Mähönen
1 Institute of Biotechnology, HiLIFE, University of Helsinki, Finland 2 Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences,
University of Helsinki, Finland [email protected]
With the aggravation of global environmental problems and the reduction of finite reserved fossil fuels, seeking for
alternative energy sources has become one of the priorities for the sustainable development of human society. Vascular
plants save the biomass mainly as the form of xylem (also called as wood), which is now considered as an ideal
environmental- friendly energy resource. Wood is now being used as renewable biofuels, Biomass composites to replace
plastic and so on. The lateral meristem vascular cambium gives rise to xylem and phloem, contributes to the radial growth
of plants. Dr. Mähönen’s group choose Arabidopsis root as a model to understand the growth dynamics of vascular
cambium. Auxin is essential for various plant developmental processes. The transcription factor family AUXIN
RESPONSE FACTOR (ARF) is an important component in auxin signaling pathway, among which AUXIN RESPONSE
FACTOR5 (ARF5)/MONOPTEROS (MP) has been discovered to be essential in various plant developmental processes.
Our preliminary results suggest that ARFs function redundantly in regulating root secondary growth, ARF1 and ARF2
together are functional in regulating vascular pattern formation, and ARF16 can repress the root secondary growth and
secondary xylem formation. MP is proved to regulate cambium activity and secondary xylem formation by controlling
various auxin-response genes, ARF7 and ARF19 might also participate in this process.
34. Simultaneous determination of hypericins and their putative precursors
(emodin, skyrin and skyrin derivatives) from Hypericum perforatum shoot
cultures
Pradeep Matam, Piotr Kachlicki, Gregory Franklin
Institute of Plant Genetics of the Polish Academy of Sciences, Poznan, Poland
Hypericum extracts are used in the treatment of several ailments including mild to moderate depression since ancient
times. Hypericin, a major constituent of the Hypericum extract is also considered as a lead molecule in the development
of drugs and diagnostic tools. Although several studies have been performed to understand the biosynthesis of hypericin,
precursors and genes participating in the process are still presumptive. In order to validate the functions of genes and
precursors presumed to participate in the biosynthesis of hypericin, an analytical method that could simultaneously
determine hypericins and their plausible precursors is warranted, which is reported in this study. Hypericum perforatum
compounds extracted in various solvents viz. ethanol, aqueous methanol, ethylacetate, acetone and dichloromethane
were separated by Ultra-performance liquid chromatography (UPLC) method, quantified by photo diode array/
fluorescence (PDA-FLR) and annotated by Q- Exactive Orbitrap mass spectrometer (UPLC-QE-MS) in the negative
ion mode. Hypericins (hypericin, pseudohypericin, protohypericin and protopseudohypericin) and their presumed
precursors (emodin, skyrin and skyrin derivatives) were efficiently detected, identified and quantified in the present
study. This is of great interest for the quality control of Hypericum extracts in the pharmaceutical industry and for the
dissection of the hypericin biosynthesis pathway.
35. Singlet oxygen, flavonols and photoinhibition in green and senescing silver
birch leaves
Heta Mattila1, Pooneh Sotoudehnia1, Telma Kuuslampi1, Ralf Stracke2, Esa Tyystjärvi1
1 Molecular Plant Biology, University of Turku, Finland 2 Genetics and Genomics of Plants, Bielefeld University, Germany
In high latitudes, deciduous trees degrade chlorophyll, to recycle nutrients, and drop off their leaves every autumn. In
addition, some compounds, such as flavonols, are synthetized in senescing leaves. We measured the production of
singlet oxygen, a reactive oxygen species, and the rate of photoinhibition in high light from both green and senescing
leaves, with different flavonol contents, of silver birch (Betula pendula). Senescing leaves produced significantly more
singlet oxygen and photosystem II (PSII) was inhibited faster when compared to green leaves. Based on chlorophyll
fluorescence and P700 absorbance parameters, the amount of both PSI and PSII contents decreased during senescence
but the remaining PSII units stayed functional until most of the chlorophyll was degraded. Contrary to the
photoinhibition of PSII, the amount of PSI photoinhibition during high light was not greatly enhanced in senescing
leaves. The amount of flavonols in the leaves did not correlate with the rate of singlet oxygen production in birch leaves
or PSII and PSI photoinhibition in Arabidopsis thaliana mutants incapable of synthetizing flavonols.
36. Upsets arose by MKK3 and MKKK17 genes on the cell fortune in the
stomatal lineage in Arabidopsis at transcript level
Syed Muhammad Muntazir Mehdi, Filip Mitula, Malgorzata Tajdel-Zielinska and Agnieszka Ludwikow
Adam Mickiewicz University in Poznan, Institute of Molecular Biology and Biotechnology,
Department of Biotechnology, Uniwersytetu Poznańskiego 6, 61-614 Poznan, Poland
MAPkinases (MAPKs) are essential elements of signaling cascades and these affect stomatal development. It had been
already described that these kinases regulate plant growth and development by the genetic manipulation of ABA-
induced MAPK cascades but our study shows that these are involved also in stomatal development under normal
conditions. In Arabidopsis, the mkkk17 and mkk3mkkk17 double mutant lines behaved differently in case of abaxial
stomatal index and stomatal aperture under normal growth conditions, compared with the control wild-type Columbia
line on 06_DAG and 10_DAG. In this study, we have investigated abaxial stomatal index and stomatal aperture under
normal growth conditions and also to observe the transcript levels of transcriptional factors in knockout as compared to
the control wild-type Columbia line on 04_DAG, 06_DAG and 10_DAG. By observing transcript levels of different
transcriptional factors (which are mostly responsible for abaxial stomatal index and stomatal aperture) such as TMM,
SPCH, MUTE, YDA,
FAMA, ERECTA and MYB88, it had been observed that all these transcriptional factors are expressed and
downregulated at transcriptional level especially in 10_DAG seedlings in mkk3mkk17 knockout as compared to wild-
type, under normal conditions. Whereas some transcriptional factors such as SPCH, MYB88, ERECTA, FAMA and
YDA were expressed as more downregulated in 06_DAG seedlings in knockout as compared to wild-type seedlings,
which can suggest us that these transcriptional factors are affected because of this gene which can play important role
in stomatal development at the initial stage of the plants and can decide the fate of the stomatal cell’s growth in plants.
Our results show that this kinase can have also crucial function in related to stomatal growth and development in
Arabidopsis as knockout had affected the transcriptional factors expression levels shown in Real-Time qPCR
experiment.
This work has been supported by the Polish National Science Centre grant No. 2016/22/E/NZ3/00345 and
POWR.03.02.00-00-I022/16.
37. Stomatal regulation of real plants
Egon Meigas, Ebe Merilo
University of Tartu, Institute of Technology, Plant Signal Research Group. Tartu, Estonia
Human population keeps rising, while climate change affects current and future crop production. To ensure food
security, plant breeders need to present new, high yielding and stress-tolerant plant lines, which means that
photosynthesis, transpiration and stomatal regulation, the fundamental pillars of plant production, need to be thoroughly
studied and understood. Thus, more attention should be paid to food crops compared to model plants. With that said, in
order to gain new insight into stomatal regulation, we need to also study its regulation in evolutionarily old species.
Here, stomatal conductance, net assimilation rate and their ABA- and CO2 responsiveness of different crop plants were
studied using custom-made gas exchange equipment. We found, that maize is characterized by significantly lower
steady-state stomatal conductance in normal conditions, reduced sensitivity of photosynthesis to changes in CO2
concentration and relative stomatal tolerance to the ABA concentration used, when compared to wheat. The values for
steady-state net assimilation rate in normal conditions were similar in both species. We also present results about: 1)
stomatal regulation of horsetails – an evolutionarily old plant group whose stomatal regulation has not been studied yet
and 2) genotype-specific differences in ABA-responsiveness of seven European malting barley cultivars. We found that,
there are important differences between studied plants regarding their CO2- and ABA-sensitivity. With the inclusion of
these non-model species, we aim to provide valuable knowledge about stomatal regulation in a broader spectrum, so we
could one day help develop better adapted crops for future climate.
38. Acetylation of chloroplast proteins: implications on plastid metabolism
Paula Mulo1, Minna M. Koskela1, Aiste Ivanauskaite1, Magda Grabsztunowicz1, Esa Tyystjärvi1, Ines Lassowskat2, Ulla
Neumann3, Trinh V. Dinh4, Julia Sindlinger5, Dirk Schwarzer5, Markus Wirtz4, Carmela Giglione6 and Iris Finkemeier2
1 Department of Biochemistry, Molecular Plant Biology, University of Turku, Finland 2 Plant Physiology, Institute of Plant Biology and Biotechnology, University of Muenster, Germany 3 Central Microscopy, Max Planck Institute for Plant Breeding Research, Germany 4 Department of Plant Molecular Biology, Centre for Organismal Studies, Heidelberg University, Germany 5Interfaculty Institute of Biochemistry, University of Tübingen, Germany. 6Institute for Integrative Biology of the Cell (I2BC), Université Paris-Sud, Université Paris-Saclay, France
Plants must respond to a wide range of signals to coordinate their growth, reproduction and survival within a constantly
changing environment. Environmental responses may be achieved through post-translational modifications of proteins,
which allow rapid and flexible changes in cellular and physiological outputs. Recent methodological progress in mass
spectrometry and enrichment techniques has revealed that numerous chloroplast proteins are targets of N-terminal and/or
lysine acetylation. Despite constantly increasing amount of identified acetylated proteins, characterization of the
responsible enzymatic machinery in chloroplasts, as well as understanding the physiological significance of acetylation
is in its infancy. We have performed bioinformatic analysis and identified a family of proteins predicted to act as
chloroplast acetyltransferases. Fusion of the candidate enzymes to fluorescent protein revealed several putative
acetyltransferases as chloroplast proteins, and in vitro analyses proved their enzymatic activity. Loss of the chloroplast
acetyltransferase NSI resulted in a major molecular phenotype with defective photosynthetic state transitions, possibly
due to decreased acetylation of several chloroplast proteins. We are currently characterizing the physiological functions
of the entire chloroplast acetyltransferase family.
39. Bioenergetics and proteome dynamics of cyanobacterium Synechocystis
sp. PCC6803 under different trophic conditions
Dorota Muth-Pawlak, Tuomas Huokko, Yagut Allahverdiyeva, Eva-Mari Aro
Molecular Plant Biology Group, Department of Biochemistry, University of Turku, Turku, Finland
Cyanobacterium Synechocystis sp. PCC6803 is a prokaryote able to perform oxygenic photosynthesis. The simple
genome and the ability to acclimate to various environmental conditions have made them useful as the model organisms
in photosynthesis studies and they also have attracted attention as a chassis for living factories Transduction of solar
energy into chemical energy via complex photosynthetic machinery is tightly integrated with the carbon dioxide
assimilation system and downstream metabolism of the cells. The cross talk between these processes must be under
strict control in order to maintain cell homeostasis. Synechocystis cells may experience very diverse environmental and
their ability of quick acclimation to severe habitats also rely on their capability of heterotrophic growth. In order to
understand the flexibility of Synechocystis metabolism, high throughput mass spectrometry (MS) based proteomics
approach was applied. We investigated the rearrangement of proteome under autotrophic carbon enriched (AT/HC) and
ambient CO2 conditions (AT/LC) as well as under mixotrophic (MT) and light activated heterotrophic growth (LAHG)
conditions. We identified and quantified of 80% and 55% of Synechocystis proteome respectively. The largest
differences, among annotated proteins, were spotted within photosynthetic and respiratory proteins as well as among
inorganic carbon or phosphate transporters depending on condition. In-depth analysis showed upregulation (to different
level) of respiratory NDH-11 and NDH-2 proteins under MT and LAHG conditions while terminal oxidases were
downregulated. Closer look towards glycolysis showed enhanced flow towards different amino acids biosynthetic
pathways under MT and LAHG conditions.
40. Gibberellic Acid Promotes Xylem Proliferation by Respecifying the
Cambium Stem Cell Niche
Riikka Mäkilä1,2, Ondrej Smetana1,2 and Ari Pekka Mähönen1,2
1 Institute of Biotechnology, HiLIFE, University of Helsinki 2 Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences,
University of Helsinki
Correspondence: [email protected]
Cambial cell divisions lead to formation of secondary vasculature and thus radial growth of plants. We have recently
shown that local auxin maximum positions the stem cell organizer of the vascular cambium in Arabidopsis roots.
Gibberellic acid (GA) has been shown in multiple contexts to interact with auxin signalling and transport and it promotes
xylem cell expansion and proliferation during secondary growth. For these reasons we wanted to study how GA
regulates cambium development. First we studied the effect of GA during the secondary growth. Vasculature diameters
of GA-treated plants and mutants lacking GA (ga1) are similar to wild type. But there are differences in the xylem:
treated plants produce significantly more secondary xylem cells, whereas ga1 has a reduced number of them. These data
shows that GA is required to promote xylem proliferation during the secondary development. Lineage tracing is a
method to identify progeny of a single cell within a tissue. To understand intercellular dynamics during secondary
development, we performed lineage tracing analysis in mature root. It revealed that GA application leads to
respecification of stem cell organizer on the phloem side of the cambium, and thus increased xylem production. Since
our previous studies have shown that local auxin maximum positions stem cell organizer of the vascular cambium, we
began to investigate whether changes in auxin accumulation would explain the GA-induced phenotype. Preliminary
results suggest that GA application enhances and broadens auxin response and consequently organizer marker
expression in the vascular cambium, thus supporting our hypothesis.
41. Systematic physicochemical and proteomic analyses of chickpea provide
global view of thermotolerance responses
Akanksha Pareek, Subhra Chakraborty and Niranjan Chakraborty
NIPGR, New Delhi, India
Elevation in temperature above optimum level drastically reduces crop yield world-wide. Due to the complexity of high
temperature stress (HTS) responses, understanding the molecular basis of thermotolerance has remained a major
challenge for sustainable agriculture. Chickpea, being a winter crop, is hypersensitive to HTS and its growth is hampered
when temperature exceeds 35ºC. To delineate thermotolerance responses, seedlings of several chickpea cultivars were
subjected to HTS, and stress-induced physicochemical changes were evaluated. The changes in osmotic potential,
photosynthetic pigments, electrolyte leakage and lipid peroxidation, besides accumulation of phenolics and flavonoids
were examined. We also investigated differential expression of stress-responsive genes, particularly those coding for
heat shock proteins (HSPs) and antioxidant enzymes. One of the important class of HSPs, chaperonin 10 (Cpn10), which
assists protein folding and assembly showed HTS-induced differential accumulation. In plants, Cpn10 is localized to
mitochondrial and chloroplast matrix, while it is imported to nucleus in animal cells. Significantly, this study revealed
its nuclear localization in plants as well and confirmed its role in multiple stress tolerance. Next, we developed HTS-
responsive nuclear proteome, which constitutes the complex network of proteins involved in stress adaptation. Screening
of the proteomes of unstressed control and HTS-treated seedlings revealed 2705 differentially expressed proteins. The
comparative proteomics analysis led to the identification of HTS-responsive proteins, involved in multivariate cellular
processes. This combinatorial approach would generate detailed information about the intrinsic mechanism of HTS
responses in plants as it would correlate the possible relationship between differential physicochemical attributes and
proteomic profiles in genotype-specific manner.
42. Post-translational regulation of organelle-induced stress responses
Jesús Pascual Vázquez 1, Martina Angeleri1, Moona Rahikainen1,Sara Alegre1, Matthew Jones2 and Saijaliisa
Kangasjärvi1 1Molecular Plant Biology, University of Turku, Finland 2School of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, United Kingdom
Environmental-dependent organellar retrograde signals are vital in stress sensing and response in plants. We have
identified Protein Phosphatase 2A (PP2A) as a cytosolic factor that modulates stress acclimation and pathogenesis
responses in Arabidopsis thaliana. PP2A regulatory subunit B’γ (PP2A-B’γ) is required to maintain growth and prevent
premature developmental leaf senescence under favorable conditions. On a molecular level, PP2A-B’γ controls a
network of transcriptomic, proteomic and metabolic alterations elicited by organellar ROS signals and that resembles
chloroplastic and mitochondrial dysfunction-induced responses. PP2A-B’γ physically interacts with several organelle-
induced stress response proteins, such as ACONITASE 3 (ACO3), ALTERNATIVE OXIDASE 1A (AOX1A) and
SULPHOTRANSFERSAE 12 (SOT12), regulating its abundance under optimal grow and stress recovery conditions.
PP2A-B’γ also controls the recovery of basal levels of the organelle stress signalling metabolite 3′-phosphoadenosine-
5′-phosphate (PAP). Furthermore, the promoter of PP2A-B’γ itself is a target for transient inactivation by organellar
dysfunction signals triggered using UV-B and the knockdown of the protein leads to a susceptible phenotype in the
recovery phase following UV-B treatment. Consequently, we have evidences that suggest the existence of a post-
translational regulatory network governed by PP2A-B’γ and that is essential to prevent unnecessary stress reactions and
restore growth and development upon stress relief.
43. Synthetic biology toolbox for cyanobacterial engineering
Pekka Patrikainen, Csaba Nagy, Hariharan Dandapani, Kati Thiel, Lauri Kakko, Edita Mulaku, Eerika Vuorio, Eva-
Mari Aro and Pauli Kallio
Molecular Plant Biology, Department of Biochemistry, University of Turku, 20520 Turku, Finland
Due to their ability to grow solely on sunlight and carbon dioxide, cyanobacteria have become an interesting target host
for the environmentally friendly production of carbon-based chemicals. However, the commercial production is still
hindered by the lack of efficient production systems. This is especially related to the lack of reliable knowledge about
the genetic elements required for efficient engineering of cyanobacteria. Although several studies have tried to tackle
this issue, direct transformation of information and tools between different laboratories has proven to be difficult. We
have taken a systematic approach to generate a validated synthetic biology toolbox for efficient engineering of various
cyanobacterial species. This toolbox consists of different promoters and RBSs for accurate modulation of transcriptional
and translational efficiencies, respectively. The elements from these libraries can be assembled in different combinations
with desired biosynthetic genes by using two different cloning strategies: BioBrick-based iterative cloning system or
Golden Gate -derived PCR-based cloning method. Stable expression of assembled pathways is achieved either from
different chromosomal integration sites or from replicative plasmids. Currently, we have validated these libraries in
Synechocystis, but the use of broad-host range expression plasmid enables also the use of other cyanobacterial species
as production hosts. This synthetic biology toolbox gives us a possibility to enhance the throughput of preparative phase
of pathway assembly, improve the regulation, predictability and efficiency of these pathways and optimize the
translational levels of different pathway genes. By combining all these aspects, we can meet the increasing demands for
the efficiency in cyanobacterial engineering.
44. Root-type ferredoxin-NADP+ oxidoreductase isoforms in Arabidopsis
thaliana
Marjaana Rantala1, Magda Grabsztunowicz1, Aiste Ivanauskaite1, Tiina Blomster2, Anne Rokka3, Irum Farooq1, Esa
Tyystjärvi1, Eva-Mari Aro1, Meike Burow4,5, Kirk Overmeyer2, Ari Pekka Mähönen2 and Paula Mulo1
1 Department of Biochemistry, Molecular Plant Biology, University of Turku, Biocity A, Finland. 2 Institute of
Biotechnology, HiLIFE/Organismal and Evolutionary Biology Research Programme, Faculty of Biological and
Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Finland. 3 Turku Center for
Biotechnology, University of Turku and Åbo Akademi University, Finland. 4 DynaMo Center, Department of Plant and
Environmental Sciences, University of Copenhagen, Denmark. 5 Copenhagen Plant Science Centre, Department of Plant
and Environmental Sciences, University of Copenhagen, Denmark
Ferredoxin-NADP+ oxidoreductases (FNR) belong to a family of nuclear-encoded enzymes, which catalyze electron
transfer between ferredoxin (Fd) and NAD(P)H. The chloroplast-located leaf-type (L)FNRs have been extensively
studied and are known to function in the last step of photosynthetic light reactions by mediating the transfer of electrons
from Fd to NADP+. In non-photosynthetic plastids, the root-type (R)FNRs function in opposite direction by transferring
electrons from NADPH to Fd, which is utilized in e.g. nitrogen and sulfur assimilation and fatty acid desaturation. Apart
from the suggested role in these processes, the characterization of the RFNRs has remained largely obscure. In
Arabidopsis, two root-type FNR isoforms (RFNR1 and RFNR2) exist and are expressed both in roots and leaves. In the
present study, the more specific location and distinct functional roles of the two RFNR isoforms in Arabidopsis thaliana
were examined. The promoter activity assays with GUS reporter gene and the localization of GFP-tagged RFNR
isoforms with confocal microscopy demonstrated that RFNR1 and RFNR2 are expressed in different parts of root and
leaf tissues, RFNR1 being abundant in leaf veins and stele of root and RFNR2 specifically in leaf tips and root cortex.
The analysis of RFNR accumulation upon abiotic stress conditions revealed that RFNR2 isoform responded to short-
term cold treatment whereas RFNR1, exclusively, accumulated upon exposure to ozone. Altogether, our results provide
novel characterization of the RFNR isoforms in Arabidopsis and show that despite their partial functional redundancy,
the two isoforms also carry out specific functions upon response to abiotic stress.
45. Cytokinin responsiveness involves RNA methylation during Arabidopsis
development
Raili Ruonala1, Eva Hellmann2, Donghwi Ko2, Hanna Help-Rinta-Rahko1, Huili Liu2, Sedeer el-Showk1, Ronni
Nielsen3, Anders Haakonsson3, Ondrej Novak4, Miriam Llorian5, Tanya Waldie2, Zsuzsanna Bodi6, Susanne Mandrup3,
Karin Ljung4, Liisa Holm1, Rupert Fray6, Markku Varjosalo1, Chris Smith5, Ottoline Leyser2, Finn Kirpekar3, Ykä
Helariutta1, 2
1 Institute of Biotechnology / Department of Biosciences, University of Helsinki, Finland 2 The Sainsbury Laboratory, University of Cambridge, United Kingdom 3 Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark 4 Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Umeå, Sweden 5 Department of Biochemistry, University of Cambridge, United Kingdom 6 Plant Sciences Division, University of Nottingham, United Kingdom
We study cell patterning events involved in plant vascular development, utilizing the Arabidopsis primary root as our
model system. Earlier, we have shown that phytohormones cytokinin and auxin interactively specify vascular patterning
during root development. To identify novel factors that may participate in the cytokinin and auxin signalling pathways,
and modify vascular patterning, we perform genetic screens for mis-expression of specific markers in the Arabidopsis
primary root. One such marker for vascular patterning is ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN
6 (AHP6), a spatially specific inhibitor of cytokinin signalling that is also regulated by auxin (Mähönen et al. 2006).
Based on this approach, we have recently identified two loci that are involved in RNA methylation. Here, we introduce
a mutant initially distinguished by an expanded AHP6 expression domain in a cytokinin hyposensitive background. This
novel mutant is also characterized by a distinct shoot developmental phenotype. Furthermore, the mutation can induce
the production of a storage root -like structure in Arabidopsis, characteristic to some crop species (such as radish or
turnip) of the Brassicaceae family. We study how the RNA modification affects cytokinin responsiveness and
development in the Arabidopsis root and shoot.
46. Differential behavior of silver and gold nanoparticles on the induction of
oxidative stress in Hypericum perforatum cells
Rajendran Kamalabai Selvakesavan, Franklin Gregory*
Institute of Plant Genetics of the Polish Academy of Sciences, Poznan, Poland
*Corresponding Author: [email protected]
Hypericum perforatum response to treatment with silver nanoparticles (SNP) and gold nanoparticles (GNP) has been
studied in cell suspension cultures. Parameters associated with oxidative stress were evaluated in H. perforatum cell
suspension cultures after treating them with 25 mg/l of either SNP or GNP. Although a drastic reduction of cell viability
was observed in cultures treated with SNP, cell viability was not affected in cultures treated with GNP. Furthermore,
SNP treatment was also observed to swiftly increase intracellular reactive oxygen species (ROS) production, unlike
GNP treatment, where no such response observed for up to 24 hours. Genes encoding polygalacturonase inhibitor protein
and phenolic oxidative coupling protein were upregulated in both SNP and GNP treatment indicating the induction of
pathogenesis related defense mechanism in the cells by both of these nanoparticles. Genes encoding enzymes
benzophenone synthase, 1,3,5-trihydroxyxanthone synthase, and 1,3,7-trihydroxyxanthone synthase were upregulated,
CHS was downregulated suggesting that xanthone biosynthesis is upregulated at the expense of flavonoid biosynthesis
after nanoparticles treatment. Catalase (CAT) gene expression increased following SNP treatment, whereas its
expression remained unchanged in GNP treatment. Together our study concludes that H. perforatum cells recognize
both SNP and GNP as a threat and stimulate its defense response in various forms and that SNP affect cell viability
plausibly by inducing a strong oxidative stress.
47. Increased expression of mitochondrial dysfunction stimulon genes affects
chloroplasts in Arabidopsis
Alexey Shapiguzov1,2, Lauri Nikkanen3, Duncan Fitzpatrick3, Richard Gossens1,2, Julia P. Vainonen1,2, Arjun Tiwari3,
Klará Panzarová4, Zuzana Benedikty4, Martin Trtílek4, Eva-Mari Aro3, Eevi Rintamäki3, and Jaakko Kangasjärvi1,2
1.Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences,
University of Helsinki, FI-00014 Helsinki, Finland 2Viikki Plant Science Center, University of Helsinki, FI-00014 Helsinki, Finland 3. Department of Biochemistry / Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland 4 Photon Systems Instruments, 664 24 Drásov, Czech Republic
Mitochondrial retrograde signals control expression of nuclear mitochondrial dysfunction stimulon (MDS) genes. MDS
gene products mostly affect mitochondrial functions. For example, they encode alternative oxidases (AOXs) that alter
mitochondrial respiration. In addition, MDS genes by yet unknown mechanisms influence the chloroplast. MDS-
overexpressing plants demonstrate changed redox state of chloroplast thiol enzymes and increased tolerance to methyl
viologen (MV). MV is the catalyst of Mehler’s reaction, the electron flow from Photosystem I to molecular oxygen,
which generates reactive oxygen species (ROS). To study this interaction between the organelles, we analysed
chloroplast functions of the Arabidopsis MDS-overexpressing mutant rcd1. The chloroplast master thiol regulator
NADPH-thioredoxin oxidoreductase C (NTRC) was more reduced in rcd1. NTRC contributed to photosynthetic
phenotypes of rcd1, but did not explain its MV tolerance. MV treatment caused rearrangements in photosynthesis and
suppressed oxygen evolution both in rcd1 and the wild type. However, in rcd1 prolonged illumination aborted the
activity of MV. Similar inactivation of MV occurred under hypoxic atmosphere. Our results suggest that MDS gene
products supress Mehler’s reaction through decreasing cellular oxygen availability. Chloroplast ROS act as the electron
sink for thiol redox enzymes. Thus, lower ROS production could explain more reduced states of these enzymes. The
significance of this effect in physiological situations other than MV stress is to be investigated. However, transcriptomic
meta-analysis revealed significant similarity between transcriptional changes under MDS-inducing versus hypoxic
conditions, suggesting that the two stresses are linked. This regulation may represent a novel mechanism whereby
mitochondrial retrograde signalling and respiration affect chloroplasts.
48. Strigolactone regulation of tree architecture
Su Changa, Nieminen Kaisab, Helariutta Ykäa,c
aUniversity of Helsinki, Finland bNatural Resources Institute Finland, Finland cSainsbury Laboratory, Cambridge, United Kingdom
Birch (Betula pendula) is a pioneer forestry species, which broad geographical distribution in the Northern Hemisphere
accompanies an extensive natural variation. Thus, the study of different tree architectures and wood traits could
significantly improve forest breeding, forest management and wood harvesting. Therefore we created a collection of
different birch natural variants. Here we focus on nine bushy phenotypes (“Kanttarelli”, “Luutakoivu”, “table birch”,
“cloud birch”, “Luuta E8032”, “Peera 6”, “Peera 16”, “Peera 28”). From phenotyping analysis, we concluded they all
have comprised primary growth and in most of them secondary growth is reduced compared to WT birches. After a
candidate gene approach we identified in the “Kanttarelli” cultivar, a mutation that disrupts BpMAX1 gene which
encodes a strigolactones (SLs) biosynthetic enzyme. Birch BpMAX1 and its promoter are functionally conserved since
they complement the Arabidopsis max1 mutant. To characterize the shoot phenotypes and understand how SLs affect
tree architecture, we performed BpMAX1 knockdown in birch by RNAi technology and the trees showed bushy
phenotype. We used National Plant Phenotyping Infrastructure to dissect 3D architectural characteristics of trees. This
approach provided us numerical data with high resolution images. Moreover, we found the key parameters to define tree
architecture. Additionally, we studied the gene expression pattern of BpMAX1. RNA-seq data indicates that BpMAX1
expression peaked in xylem through the whole stem. Interestingly, pBpMAX1::GUS marker line indicated that this
expression specifically occurs in ray parenchyma cells, which might act as source of SL biosynthesis in trees (during
loading or unloading of the mobile SL precursor from the xylem).
49. The integration of developmental signals during root procambial
patterning in Arabidopsis
Iris Sevilem1, Shunsuke Miyashima1,2, Pawel Roszak1,3, Koichi Toyokura3,4, Bernhard Blob3, Jung-ok Heo1,3, Nathan
Mellor5, Hanna Help1, Sofia Otero3, Wouter Smet6,7,8, Mark Boekschoten9, Guido Hooiveld9,
Kayo Hashimoto2,10, Ondřej Smetana1, Riccardo Siligato1, Eva-Sophie Wallner11, Ari Pekka Mähönen1, Yuki Kondo12,
Charles W. Melnyk3,13, Thomas Greb11, Keiji Nakajima2, Rosangela Sozzani14, Anthony Bishopp5, Bert De Rybel6,7,8
&Ykä Helariutta1,3
1Institute of Biotechnology, HiLIFE/Organismal and Evolutionary Biology Research Programme, Faculty of Biological and
Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland. 2Graduate School of Science and
Technology, Nara Institute of Science and Technology, Nara, Japan. 3The Sainsbury Laboratory, University of Cambridge,
Cambridge, UK. 4Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan. 5Centre for
Plant Integrative Biology (CPIB) and School of Biosciences, University of Nottingham, Nottingham, UK. 6Department of Plant
Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium. 7VIB Center for Plant Systems Biology, Ghent, Belgium. 8Laboratoryof Biochemistry, Wageningen University, Wageningen, The Netherlands. 9Nutrition, Metabolism and Genomics Group,
Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands. 10Graduate School of Humanities and
Sciences, Nara Women’s University, Nara, Japan. 11Centre for Organismal Studies (COS), Heidelberg University, Heidelberg,
Germany. 12Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan. 13Department
of Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden. 14Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA.
The vascular system of plants functions in transportation while also forming a support structure and generating radial
growth. The vascular cylinder of the Arabidopsis root comprises a central xylem axis with a phloem pole on either side
and intervening procambial cells. Vascular patterning requires high auxin and cytokinin signaling domains in the xylem
and phloem/procambium positions, respectively. We discovered that radial growth is activated in the peripheral phloem
domain by six mobile DOF transcription factors downstream of cytokinin, which we named PHLOEM EARLY DOF
(PEAR) proteins. PEARs form an inverse concentration gradient to the HD-ZIP III genes which inhibit periclinal cell
divisions in the central domain. The expression of HD ZIP IIIs is promoted by auxin in the xylem axis and inhibited by
mobile microRNA165/166 in the periphery. We demonstrate that PEARs and HD-ZIP IIIs form a regulatory module
that decodes hormonal and microRNA signals to result in the formation of a highly active peripheral zone and a quiescent
central zone during procambium development. We also determined that another member of the DOF family, DOF2.1,
acts downstream of TMO5/LHW-dependent cytokinin biosynthesis to regulate periclinal cell divisions in the outer
procambial cells in contact with the xylem axis. PEAR and DOF2.1 proteins control all of the periclinal divisions in the
procambium through their activity in partially distinct domains. Furthermore, we identified SMXL3 as a regulator of
periclinal divisions downstream of PEAR2. We have thus assembled a regulatory network coordinating procambial
development and have identified the protophloem sieve elements as the organizers.
50. Function of AtABCG22 in stomatal responsiveness to low air humidity
Ashutosh K. Pandey, Dmitry Yarmolinsky, Hannes Kollist
Institute of Technology, University of Tartu, Tartu 50411 Estonia
Guard cells operate in a close coordination with different environmental cues and hormonal stimuli thereby triggering
the signaling cascades that lead to stomatal opening or closure.Both guard cell ABA signaling and membrane transport
proteins play an important role in the regulation of plant stomatal responses. ABC transports are one of the most
conserved and abundant protein family from prokaryotes to higher eukaryotes. ABCG22 is a member of the ATP-
binding cassette (ABC) family involved in the regulation of the water retention in the plants and acts as a stomatal
regulator. However, the actual mechanism by which AtABCG22 influences stomatal regulation has not yet been
described. Interestingly, the atcbcg22 mutants exhibit a typical open-stomata (OST) phenotype such as, increased
transpiration and drought susceptibility indicating a close relation with the ABA signalling. In the present study we are
using a set of ABCG22 mutant plants to find out what kind of molecules are transported by ABCG22 by using different
metabolomic and mass spectrometric approaches.
51. Anthocyanins and dihydroflavonol 4-reductase substrate specificity in
Gerbera hybrida
Lingping Zhu, Saku Mattila, Lorenzo Mollo, Hany Bashandy and Teemu H. Teeri
Viikki Plant Science Centre, Department of Agricultural Sciences, University of Helsinki, Finland
[email protected], [email protected]
Gerbera (Gerbera hybrida) is an ornamental model plant of the Asteraceae family, with cultivars showing different
inflorescence colors and patterns. Cultivars can be grouped into anthocyanin free, pelargonidin-, cyanidin- and mixed
types. Chemical blocking of the flavonoid B-ring hydroxylation at position 3’ with the inhibitor tetcyclasis shifts the
anthocyanin composition towards pelargonidin in mixed types but blocks anthocyanin biosynthesis altogether in
cyanidin types. This rouse our interest in substrate specificity of the gerbera dihydroflavonol 4-reductase enzyme DFR,
often responsible for the choice of the anthocyanin pathway branch kept active. We characterized three allelic forms of
the enzyme. GDFR1-1 and GDFR1-2 are expressed in pelargonidin type cultivars while GDFR1-3 is expressed in a
cyanidin type cultivar that reacts to tetcyclasis by turning white. The DFR encoding sequences were expressed from
pEAQ-HT vectors in agroinfiltrated Nicotiana benthamiana leaves, which yielded highly active protein extracts. Our
expectations were that GDFR1-3 would prefer not to reduce dihydrokaempferol, the precursor of pelargonidin. Instead,
we found that GDFR1-3 does not differentiate between the three substrates leading to pelargonidin, cyanidin and
delphinidin but both GDFR1-1 and 1-2 show a strong preference for dihydrokaempferol. Now we are analyzing the
petal transcriptomes of gerbera cultivars of different anthocyanin types.
52. PGR5 and NDH-1 systems do not function as protective electron acceptors
but mitigate the consequences of PSI inhibition
Sanna Rantala, Tapio Lempiäinen, Caterina Gerotto, Arjun Tiwari, Eva-Mari Aro, Mikko Tikkanen
Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20014, Turku, Finland
Avoidance of photoinhibition at photosystem (PS)I is based on synchronized function of PSII, PSI and the stromal
electron acceptors. Here, we applied a special light treatment (PIT) in order to accumulate excess electrons at PSI with
subsequent inhibition of PS, using Arabidopsis WT and the pgr5 and ndho mutants. Each of these mutants is deficient
in one of the two main cyclic electron transfer pathways described to function as protective alternative electron acceptors
of PSI. The aim was to investigate whether the PGR5 (pgr5) and the type I NADH dehydrogenase (NDH-1) (ndho)
systems protect PSI from excess electron stress and whether these systems help plants to cope with the consequences of
PSI photoinhibition. First, our data revealed that neither PGR5 nor NDH-1 system protects PSI from a sudden burst of
electrons. This strongly suggests that these systems in Arabidopsis do not function as direct acceptors of electrons
delivered from PSII to PSI, thus contrasting with the function of flavodiiron proteins that were found to make
Physcomitrella patens PSI resistant to the PIT. Second, it is demonstrated that under light-limiting conditions, the
electron transfer rate at PSII is linearly dependent on the amount of functional PSI in all genotypes, whilst under excess
light, the PGR5-dependent control of electron flow at the Cytochrome b6f complex overrides the effect of PSI inhibition.
Intrudingly, the PIT resulted in increase in the amount of PGR5 and NDH-1 as well as of PTOX, suggesting that they
mitigate the consequences of PSI photoinhibition rather than provide protection against PSI photoinhibition.
53. Site of ROS generation in photosynthetic apparatus picks which of the
photosystem undergo photoinhibition in consequence of high light in
plants
Arjun Tiwari, Duncan Fitzpatrick, Mikko Tikkanen and Eva-Mari Aro
Molecular Plant Biology Unit, Department of Biochemistry, University of Turku, Tykistökatu 6, 6th floor FI-20520
Turku, Finland
Photosynthetic electron transfer is affected by photoinhibition of photosystem (PS) II and I. Photosystem II normally
undergoes photoinhibition on a regular basis when irradiance goes higher than that needed for optimal photosynthesis.
PSII photoinhibition is a regulatory response of plants to protect the expensive damage of photosystem I. However, PSI
is sensitive to fluctuating lights when controls over electron flow to PSI is withheld (in some mutants). Here, we have
studied the condition which favors PSI damage and how a slight change in the conditions switches the damage site from
PSI to PSII, thus, protecting PSI from damage. It is observed that production of reactive oxygen species outside the PSI
complex had inhibitory effects on PSII. On contrary, creating a reducing environment (production of ROS) deep within
the PSI complex was harmful to PSI FeS clusters. We show here in pgr5 mutant of Arabidopsis thaliana that detached
leaves if treated with a very low concentration (1 µM for 30 min) of MV completely protected PSI from damage under
high light until 2 hrs but simultaneously caused a continuous damage to PSII. Similarly, presence of an extra electron
sink in the form of flv protein by adding cloned spruce FLV1 gene in pgr5 background protected both the photosystems
under HL for a longer time.
54. The phosphorylation dynamics of CURT1B under fluctuating light
Andrea Trotta1, Azfar Ali Bajwa1, Ilaria Mancini1, Mathias Pribil2 and Eva-Mari Aro1
1 Molecular Plant Biology, Department of Biochemistry, University of Turku, Finland 2 Department of Plant and Environmental Sciences, University of Copenhagen, Denmark
The regulation of the photosynthetic apparatus in higher plants is highly connected to the organization of the thylakoid
membrane into appressed and non-appressed regions. The two photosystems (PS) are the protein complexes mostly
segregated in this organization, with PSII predominantly present in the appressed membranes (grana), while PSI is
confined to the stromal non-appressed thylakoids (lamellae). Dynamics of this lateral heterogeneity controls the
spillover of excitation energy from PSII to PSI and optimizes the photochemistry in constantly fluctuating light
conditions, also via phosphorylation of PSII core and light harvest complex II (LHCII) proteins. Recently, the CURT1
proteins and their post-translational modifications (PTMs) have been proposed as a further key component in shaping
grana in response to changes in light intensity. We have quantified by means of targeted proteomics the amount of
CURT1 proteins and the level of CURT1B PTMs after short-term fluctuating light treatments in wild type Arabidopsis
thaliana and the knock-out mutants impaired in thylakoid proteins phosphorylation. We have found that CURT1B N-
terminal acetylation and phosphorylation are mutually exclusive. Morover, the phosphorylation level, but not the
acetylation level nor the protein level, increases in light conditions that lead to sudden increase in PSII core protein
phosphorylation. Intriguingly, the phosphorylation dynamics as well as the level of the other CURT1 proteins, are highly
affected in mutant plants which lack PSII or LHCII phosphorylation dynamics. Based on these findings, we can now
draw a correlation PSII-LHCII phosphorylation, CURT1B phosphorylation and the dynamics of thylakoid appression
in fluctuating light conditions.
55. OZ.26 – a putative steroid hormone receptor involved in plant stress
tolerance
Triin Vahisalu1, Olena Zamora1,2, Marina Leal Gavarron1, Cezary Waszczak1, Dmitry Yarmolinsky2, Maija Sierla1,
Hannes Kollist2, Jaakko Kangasjärvi1
1 Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 1, Helsinki, Finland 2 Institute of Technology, University of Tartu, Nooruse 1, Tartu, Estonia
The sessile lifestyle of plants requires that adverse environmental conditions are rapidly recognized and responded to
with adequate reactions. Both abiotic and biotic stress factors induce ROS production in plants leading to the activation
of downstream signaling events. As ozone induces the production of ROS, it is an excellent tool to study plant stress
tolerance. We have conducted a large-scale forward genetics screen based on ozone sensitivity aiming to identify both
novel stomatal regulators and also components in plant stress tolerance. Mutants defective in stomatal regualtion receive
a higher ozone dose leading to visual leaf damage. Ozone sensitive mutants with normal stomatal and cuticular function
receive same ozone doze as WT but are potentially defective in ROS induced downstream signaling and/or scavenging.
Our screen has identified ~50 novel mutants impaired in guard cell signaling and surprisingly only 2 mutants with
normal stomatal regulation and strong ozone sensitivity – oz.14 and oz.26. For both of the mutants mapping populations
have been created based on ozone sensitivity phenotype and SHOREmap results are available. OZ.26 encodes a still
uncharacterized putative plant steroid hormone receptor. oz.26 mutants are highly sensitive to ozone, freezing treatment
and Pseudomonas bacteria. OZ.26 is localized to the plasma membrane and endosomes and is widely expressed in
different plant tissues including mesophyll, veins and pollen. oz.26 mutants have enhanced ozone induced MAP kinase
activatoion. Additionally, in vitro steroid hormone binding will be addressed.
56. Towards the remote VIS-NIR observation of in vivo leaf controlled
downregulation of photosynthesis
Shari Van Wittenberghe1,2, Luis Alonso1, Albert Porcar-Castell2, José Moreno1
1 Laboratory of Earth Observation, University of Valencia, C/Catedrático José Beltrán, 2, 46980 Paterna, Valencia,
Spain 2 Optics of Photosynthesis Laboratory, Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty
of Agriculture and Forest, University of Helsinki, 00014 Helsinki, Finland
Understanding the energy fluxes related to the energy dissipation of absorbed photosynthetic active radiation (APAR)
by vegetation is currently under high attention of the vegetation remote sensing community. It will allow us to better
understand and eventually monitor the functional behaviour of vegetation from a remote perspective. The functional
changes in APAR happen at the leaf level and can be studied through whole leaf in vivo spectroscopy by measuring the
upward and downward spectral radiance fluxes. The precise measurement of spectrally contiguous (hyperspectral)
transient time series of absorbance A(λ,t) and passively induced chlorophyll fluorescence F(λ,t) dynamics after sudden
strong natural-like illumination exposure provide insight into the specific pigment-pigment and pigment-protein
interactions in vivo. Intact leaves show hereby a complexity of spectral changes in the visible and near-infrared
wavelengths (VIS-NIR, 400-800 nm). In response to light excess, a strong and slow absorbance shift with peaks in the
green (550 nm) and far-red (750 nm) was observed for the first time observed. These observations are suggested to be
the in vivo evidence for a low-energy (i.e. longer wavelength) shifted re-distribution of absorption bands of respectively
Car and Chl, showing a strong exciton coupling. Such observable changes in APAR bring us to novel insights of the
energy distribution mechanism regulated by the antenna itself. They seem therefore very promising for the further
unravelling of in vivo APAR energy distribution in vegetation, and the remote VIS-NIR monitoring of plant
photosynthesis in a changing world.
57. Btr1-A gene controls spike brittleness in diploid wheat species
Valeriya Vavilova1*, Irina Konopatskaia1*,Alexandr Blinov1
1Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation
During domestication of cereal crops, one of the most important traits for human was spike brittleness. The selection
was aimed at finding plants with a non-brittle spike. It has been shown that the Non-brittle rachis 1-A (Btr1-А) gene
involved in regulation the brittle/ non-brittle spike trait in wheat (Triticum L.). In this study we investigated Btr1-A gene
for 30 accessions of diploid wheat species with brittle (Triticum boeoticum, T. urartu) and non-brittle (T. monococcum,
T. sinskajae) spikes from Southern Europe, Transcaucasia and Minor Asia. The full-length sequences of this gene,
including 3’- and 5’- UTRs, were obtained. The Btr1-A sequence for T. sinskajae was obtained for the first time.
Comparative analyses allowed us to determine 11 various haplotypes of Btr-A1 gene. Five haplotypes were described
for the first time. The non-synonymous change at the coding region of Btr1-A (G to A, A119T) were specific for all
wheat accessions with non-brittle spikes, compared to accessions with brittle spikes. Thus, in this study the role of the
Btr-A1 gene in the regulation of spike brittleness was confirmed. However, further investigations are required to
understand the potential relationship between Btr-A1 and other genes, which also control the spike morphology traits in
diploid wheat species.
The study was supported by the Russian Science Foundation (grant number: 16-16-10021-P).
58. Hit2 strain of Chlamydomonas reinhardtii produces more biomass in high
light due to increased photoinhibition resistance
Olli Virtanen and Esa Tyystjärvi
Department of Biochemistry/ Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland
The repair of photoinhibited PSII via re-synthesis of the D1-protein consumes resources, and therefore organisms in
which photoinhibitory damage occurs slowly, would be able to save energy for growth. This could provide a prospective
enhancement opportunity when considering productivity of microalgae. A previously isolated high-light tolerant strain
of C. reinhardtii, hit2, was shown to grow significantly faster in high light when compared to the wild-type due to a
single nucleotide mutation in the gene Cr-COP1 (Schierenbeck et al. 2015), later shown to be responsible for UV-B
sensing and acclimation (Tillbrook et al. 2016). In our study (Virtanen et al. 2019), hit2 was characterized to be more
tolerant to the damaging reaction of photoinhibition of PSII in vivo when grown autotrophically. Thermoluminescence
measurement indicated a smaller redox gap between QA/QA- and QB/QB
- pairs in hit2 than in the wild-type, which is a
common phenotype for some photoinhibition resistant organisms. Hit2 was also able to maintain larger antenna size in
relation to the wild-type in high light, possibly due to slower rate of photoinhibition. The strain was also shown to have
significantly larger volumetric productivity at PPFD 1250 µmol (photons) m-2 s-1. At this light intensity hit2 produced
2.53 ± 0.18 and the wild-type 2.05 ± 0.12 g biomass l-1 d-1, suggesting that the cells of hit2-strain can direct more energy
and resources to growth and accumulation of biomass, that would otherwise be used in repairing the photoinhibited
PSIIs. In contrast, in standard conditions hit2 behaves just like the used wild-type.
References:
Schierenbeck L., Ries D., Rogge K. et al.: Fast forward genetics to identify mutations causing a high light tolerant
phenotype in Chlamydomonas reinhardtii by whole-genome sequencing. – BMC Genomics 16: 57, 2015.
Tillbrook K., Dubois M., Crocco C.D. et al.: UV-B perception and acclimation in Chlamydomonas reinhardtii. – Plant
Cell 28: 966–983, 2016.
Virtanen O., Valev D., Kruse O. et al.: Photoinhibition and continuous growth of the wild-type and a high-light tolerant
strain of Chlamydomonas reinhardtii. – Photosynthetica 57:617–626, 2019.
59. Phenotyping viral infection in sweetpotato using a high-throughput
chlorophyll fluorescence and thermal imaging platform
Linping Wang, Sylvain Poque, Jari P.T. Valkonen*
Department of Agricultural Sciences, University of Helsinki, P.O. Box 27, Helsinki 00014, Finland
Sweetpotato virus disease develops in co-infection with Sweet potato feathery mottle virus and Sweetpotato chlorotic
stunt virus and causes severe losses in sweetpotato production (Ipomoea batatas) and can reduce yields by 98%. We
used an imaging-based high-throughput plant phenotype platform to study plant-virus interactions in a non-destructive
manner. We monitored the effects and stress caused by viral infection in sweetpotato over 29 days with respect to
physiological and morphological differences, photosynthetic performance, and leaf thermography. In addition, relative
gene expression in photosynthesis and carbon fixation pathways was assessed, as was viral accumulation and
distribution among sweetpotatoes infected with four virus treatments and two healthy controls. Statistical differences
observed with chlorophyll fluorescence (ChlF) of PSII and thermal infrared (TIR) imaging correlated with
morphological differences and virus accumulation in the plants. These findings were further validated at the molecular
level by related gene expression. Moreover, we showed that operating efficiency of PSII and photochemical quenching
were more sensitive parameters for quantification of virus effects as compared with maximum quantum efficiency, non-
photochemical quenching, and leaf temperature. Our study validates the use of ChlF- and TIR-based imaging systems
for distinguishing the severity of viral symptoms in sweetpotato in the laboratory and field.
Keywords: chlorophyll fluorescence imaging; gene expression; photochemical quenching; sweetpotato; thermal infrared
imaging; virus disease.
60. OPENER is a nuclear envelope and mitochondria localized unknown
protein required for cell cycle progression in Arabidopsis
Wei Wang1 and Totte Niittylä1
1 Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural
Sciences, Sweden
Currently about 30% of the proteins encoded by the Arabidopsis (Arabidopsis thaliana) genome are of unknown
function. Some of these unknown proteins are likely to be involved in uncharacterized vital biological processes.
Evolutionarily conserved single copy genes in flowering plants have been shown to be enriched in essential
housekeeping functions. This together with publicly available gene expression data allows for a focused search for
uncharacterized essential genes in Arabidopsis. This led to the identification of an essential single copy gene we
named OPENER (OPNR). OPNR performs essential functions during zygote development, embryogenesis, and
meristem cell proliferation in root tips. Cell cycle tracking using 5-ethynyl-2'-deoxyuridine staining and fluorescent cell
cycle markers together with the increased size of nucleolus and nucleus in opnr mutants indicate that OPNR is required
for cell cycle progression through the S or G2 phases. Intriguingly, OPNR localizes to both the nuclear envelope and
mitochondria. Furthermore, the nuclear envelope localization of OPNR is dependent on its interaction with nuclear inner
membrane Sad1/UNC-84 (SUN) domain proteins SUN1 and SUN2. And OPNR also interacts with mitochondria
localized proteins prohibitin 3 and 4 (PHB3 and 4). I will present our latest results from the OPNR investigation into an
evolutionarily conserved essential cellular process occurring in both the nuclear envelopes and mitochondria of dividing
cells.
References:
Wang W, Zhang X, Niittylä T (2019) OPENER Is a Nuclear Envelope and Mitochondria Localized Protein Required
for Cell Cycle Progression in Arabidopsis. Plant Cell, 31: 1446-1465.
Related Plant Cell editorial in brief: Fear Not the Unknown: OPENER as a Study in Shedding Light on Genes with
Unknown Function. Plant Cell, 31: 1420.
61. A tool for conditional genome editing in Arabidopsis
Xin Wang1,2, Lingling Ye1,2, Robertas Ursache3, Ari Pekka Mähönen1,2,*
1 Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki 00014, Finland 2 Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, and
Viikki Plant Science Centre, University of Helsinki, Helsinki 00014, Finland 3 Department of Plant Molecular Biology, Biophore, Campus UNIL-Sorge, University of Lausanne CH-1015, Lausanne,
Switzerland
*Author for correspondence: [email protected]
Conditional manipulation of gene expression is a central approach to understand the primary function of a gene in a
biological process. While conditional and cell-type specific overexpression systems exist for plants, there are currently
no system available to be able to remove gene function completely and conditionally. Here we present a novel,
conditional gene function study tool in which target genes can be efficiently knocked out at any developmental stage.
Target gene function is removed by utilizing CRISPR-CAS9 genome editing technology, and the conditionality is
achieved by well-established estrogen-inducible XVE system. If desired, target genes can also be knocked-out in a cell-
type specific manner. Our tool is easy to construct and particularly useful to study function of genes of which the null-
alleles are non-viable or they show strong developmental defects.
62. A forward genetic screen to study TMO5/LHW mediated vascular
proliferation
Brecht Wybouw1,2, Baojun Yang1,2, Jonah Nolf1,2, Helena Arents1,2, Jos Wendrich1,2, Wouter Smet1,2,3 and Bert De
Rybel1,2
1Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark 71, 9052 Ghent, Belgium 2VIB Centre for Plant Systems Biology, Technologiepark 71, 9052 Ghent, Belgium 3Wageningen University, Laboratory of Biochemistry, Stippeneng 4, 6708 WE Wageningen, the Netherlands
During plant growth, the vascular tissues have to increase in size to cope with the higher need in nutrient transport and
structural support of mature plants. This is mainly achieved by promoting radial growth through specialized divisions
called periclinal or radial divisions (PRD) which lead to the creation of new cell files. One of the main molecular
mechanisms controlling these divisions during primary root growth is the bHLH transcription factor heterodimer
TARGET OF MONOPTEROS 5/LONESOME HIGHWAY (TMO5/LHW). TMO5/LHW are both sufficient and
required to induce PRD within the vascular bundle, partly by inducing cytokinin biosynthesis through induction of
LONELY GUY 3/4 (LOG3/4). To further understand this process, we performed an EMS forward genetic screen in
order to uncover novel players in the TMO5/LHW mediated control of PRD. From this, we uncovered a new negative
regulatory network, where TMO5/LHW induces its own repressor, the MYB-type transcription factor MYB12. Our
results contribute to the further understanding of the complex regulatory network surrounding TMO5/LHW.
63. Plant growth and performance under various environmental conditions
are modulated by various stomatal regulators
Dmitry Yarmolinsky1, Mirko Pavicic2, Kristiina Himanen2, Hannes Kollist1
1 Institute of Technology, University of Tartu, Estonia 2 The National Plant Phenotyping Infrastructure, University of Helsinki, Finland
Stomata, the microscopic airway pores on plant leaves, play an important role in drought resistance as they control water
loss by plants. Although the connection between stomatal functioning and drought resistance has been studied before,
we used an opportunity to study the influence of stomatal behavior on plant development and performance under drought
combined with high light. Arabidopsis thaliana lines with mutations in different signaling pathways of guard cells were
grown under various watering and light conditions. Lines with reduced (ht1-2, aha1-6) and elevated (ost1-3, ghr1-3, a
transgenic line over-expressing HT1A109V) stomatal conductance were compared with each other and with the wild type
plants (Col-0). Plants were imaged by using RGB, thermal, and FluorCam cameras in order to characterize
morphological parameters, leaf temperature, and photosynthetic performance. Our results demonstrate that inactivation
of protein kinase HT1, a negative regulator of CO2 signaling in guard cells, resulted in an improved growth under limited
watering due to reduced stomatal conductance. We also noticed that some photosynthetic parameters, including non-
photochemical quenching (NPQ), depended on stomatal conductance in the plants which were grown under high light.
Leaf temperature corresponded to the previous information about stomatal performance in the studied mutants and was
increased in the drought-treated plants. Our results provide detailed information about plant performance under limited
watering and high light conditions. The drought resistance of the mutants with reduced stomatal conductance due to
inactivation of HT1 can be especially interesting as it provides a tool for breeding of drought tolerant crop varieties.
64. The role of jasmonic and salicylic acid in regulation of stomatal closure
Olena Zamora1,2, Dmitry Yarmolinsky1, Helen Parik1, Sebastian Schulze3, Jaanika Unt1, Julian I. Schroeder3,Mikael
Brosché1,2, Hannes Kollist1
1Plant Signal Research Group, Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia 2Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences,
University of Helsinki, FI-00014 Helsinki, Finland 3Division of Biological Sciences, Cell and Developmental Biology Section, University of California San Diego, 92093
La Jolla, USA
olena.zamora@helsinkifi
The microscopic pores on plant leaves, stomata, play a central role in regulation of transpiration and the CO2 uptake for
photosynthesis in mesophyll cells. Stomata are formed by guard cells which control stomatal aperture in response to a
number of environmental and endogenous cues. Abscisic acid (ABA) is a plant hormone which induces fast stomatal
closure and is involved in stomatal reactions to environmental stimuli. By using a genetic approach in Arabidopsis and
tomato, we aimed to evaluate the impacts of other hormones, jasmonic and salicylic acid (JA and SA, respectively), on
stomatal functioning under changing environmental conditions. Intact plants and their leaves were treated with elevated
CO2, darkness, ABA spray, reduced air humidity, and ozone pulse to induce stomatal closure. Similar to the wild type
plants, all the applied stimuli induced a reduction of stomatal conductance in the studied mutants with disturbed JA and
SA biosynthesis and signaling. Additionally, we sprayed Arabidopsis wild-type intact plants with methyl-JA and SA to
study their ability to induce stomatal closure. Biological effects of sprays with methyl-JA and SA were confirmed by
expression of hormone-induced transcripts in the treated plants. In contrast to ABA, methyl-JA and SA did not induce
a pronounced reduction of stomatal conductance. Our results indicate that, JA and SA do not play a significant role in
stomatal closure induced by environmental stimuli.
65. Long-term light and temperature memory of chlorophyll a fluorescence
Chao Zhang
Department of Forest Sciences, University of Helsinki, Latokartanonkaari 7, 00790 Helsinki, Finland
Chlorophyll a fluorescence (ChlF) are photons emitted during the photosynthetic light reaction, and can be remotely
measured as sun-induced fluorescence (SIF). SIF is currently a widely accepted good indicator of gross primary
productivity due to its direct connection with the photosynthetic electron transport. It can be expected that SIF could
enable modelling mechanisms of photosynthetic light reaction and further improve the accuracy of estimation global
photosynthesis. To do that, understanding how fluorescence responds to the environment is important, but still remains
unclear. Here, we analysed more that 10 years ChlF data obtained from monitoring PAM fluorometer (MONI-PAM)
in trees growing at SMEAR-II station (Station for Measuring Forest-Ecosystem-Atmosphere Relations), Hyytiälä,
Finland. We will calculate maximum photosynthetic efficiency of photosystem II (FV/FM), photochemical (PQ) and
non-photochemical quenching (NPQ), etc. The objective is to (1) disentangle how the NPQ and ChlF respond to the
light and temperature and then to (2) build a simple mechanistic model to interpret NPQ and ChlF. We will show the
preliminary results of how our long-term ChlF parameters change with the light and temperature in last 10 years. We
will also try to show the results from the models. We hope our results can facilitate the interpreting of SIF and advance
the global photosynthesis study under ongoing climate changes.
66. The development and regulation of vascular cambium and cork cambium
in Arabidopsis roots
Jing Zhang 1,2,3, Gugan Eswaran 1,2, Juan Alonso-Serra 1,2, Melis Kucukoglu 1,2, Jiale Xiang 1,2, Weibing Yang3,
Annakaisa Elo1,2, Kaisa Nieminen 4, Teddy Damén1,2, Je-Gun Joung5, Jae-Young Yun 6, Jung-Hun Lee7, Laura Ragni 8,
Pierre Barbier de Reuille9, Sebastian E. Ahnert3,10, Ji-Young Lee 7, Ari Pekka Mähönen 1,2 and Ykä Helariutta 1,2,3
1 Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland 2 Organismal and Evolutionary Biology
Research Programme, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of
Helsinki, Helsinki, Finland 3 The Sainsbury Laboratory, University of Cambridge, Cambridge, UK. 4 Production
Systems, Natural Resources Institute Finland (Luke), Helsinki, Finland. 5 Samsung Genome Institute, Samsung Medical
Center, Seoul, South Korea. 6 Center for Genome Engineering, Institute for Basic Science, Daejeon, South Korea. 7
School of Biological Sciences, Seoul National University, Seoul, South Korea. 8 ZMBP-Center for Plant Molecular
Biology, University of Tübingen, Tübingen, Germany. 9 Institute of Plant Sciences, University of Bern, Bern,
Switzerland. 10 Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, Cambridge, UK
Vascular cambium (VC) and cork cambium (CC) are two lateral meristems that lead to radial growth in plants. VC
produced xylem (wood) and phloem; CC gives rise to phelloderm and phellem (cork, as protective layer), altogether
referred as periderm. However, our understanding on these two cambia is quite limited. In current study, we use
Arabidopsis root as a model to investigate the spatial-temporal development of VC and CC and their regulation by
various molecular regulators. For VC development, we focused on the roles of transcription factors (TFs) during its
development. By utilizing cambium cell-specific transcript profiling followed by a combination of TF network and
genetic analyses, we identify 32 cambium TFs and 62 novel TF genotypes displaying an array of cambial phenotypes.
Cambial activity is virtually lost when both WOX4 and KNAT1 were mutated, thereby unlocking the genetic redundancy
in the regulation of cambium development. We also identified TFs with dual functions in cambial cell proliferation and
xylem differentiation, including WOX4, SVP and PTL. By combining overexpression of WOX4 and removal of the
putative inhibitor PTL, radial growth is enhanced, highlighting their centre roles in cambium development. For CC
development, we analysed various markers to find several genes are expressed in certain layers of periderm. From
mutant phenotype characterization, we identified the roles of Blind-like R2R3-MYB for periderm formation. We also
performed molecular ablation of CC to follow the regeneration of periderm. Finally, the importance of the coordination
of both cambia to guarantee a proper radial growth is highlighted.
67. TCP and MADS-box transcription factors cooperate to regulate CYC2
clade TCP genes in defining flower type identity in Asteraceae
Yafei Zhao1, Suvi K. Broholm1, Feng Wang1, Anneke S. Rijpkema1, Tianying Lan2, Victor A. Albert2, Teemu H. Teeri1
and Paula Elomaa1*
1 Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, 00014 Helsinki, Finland 2 Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA
* Address correspondence to [email protected]
Asteraceae is characterized by compressed inflorescences that combine diverse flower types. The
CYCLOIDEA/TEOSINTE BRANCHED1 (CYC/TB1)-like TCP transcription factors (TF), known to regulate bilateral symmetry of individual flowers, have been recruited to specify ray flower identity in Asteraceae. However, the
regulatory network they are involved in is poorly understood. We conducted in silico analyses, yeast one-hybrid and
transient luciferase reporter assays for identification of upstream regulators of GhCYC3, the strongest candidate in
specifying ray flower identity in Gerbera hybrida. Functional and expression studies were conducted for the candidate upstream regulators in comparison with GhCYC3 functions. We discovered that CINCINNATA (CIN)-like TCP and
MADS-box TFs are able to activate the pGhCYC3:LUC reporter through conserved binding sites in the promoter. The
CIN-like factors showed co-expression with GhCYC3 during early ray flower and bract initiation stage. Later during ray flower ligule elongation, both GhCIN1 as well as the SEPALLATA3-like TF GRCD5 were found to function
upstream of GhCYC3. Moreover, the C-class MADS-box protein GAGA1 was identified as a candidate to affect stamen
development through GhCYC3. Our data is the first to show that the TCP and MADS-box TFs cooperate in specifying
floral type identity and late organ differentiation in ray flowers, contributing to elaborate inflorescence architecture in the Asteraceae family.
68. Chromatin remodeling for the transcription of PP2C genes in response
to abiotic stress
Jong-Joo Cheong and Nguyen Hoai Nguyen
Center for Food and Bioconvergence, Seoul National University, Seoul 08826, Republic of Korea
Type 2C protein phosphatases (PP2Cs) counteract protein kinases, thereby inhibiting the abscisic acid (ABA)-mediated response to abiotic stress in Arabidopsis thaliana. Previously we reported that the transcription factor AtMYB44
contains an ETHYLENE-RESPONSIVE ELEMENT BINDING FACTOR-ASSOCIATED AMPHIPHILIC
REPRESSION (EAR) motif (LSLSL) in the C-terminal catalytic domain, and thereby physically interacts with a
TOPLESS-RELATED (TPR) corepressor. The AtMYB44-TPR complex recruit histone deacetylases and repress the transcription of PP2C genes (e.g., ABI1, ABI2, and HAI1) via the promotion of histone deacetylation around the TSS
regions at the gene loci. Recently, our quantitative reverse transcription PCR (qPCR) and chromatin
immunoprecipitation (ChIP) assays revealed that salt-induced increases in RNA polymerase-mediated transcription were reduced in 35S:AtMYB44 plants, confirming that AtMYB44 acts as a repressor of PP2C gene transcription.
Nucleosomes are evicted and AtMYB44 repressors are released from the promoter regions in response to salt stress.
Under these conditions, histone H3 acetylation (H3ac) around the TSS regions significantly increased. The salt-induced increases in PP2C gene transcription were reduced in abf3 plants, indicating that ABF3 transcription factor activates
PP2C gene transcription. Overall, our data indicate that salt stress converts PP2C gene chromatin from a repressor-
associated suppression status to an activator-mediated transcription status. In addition, we observed that the Arabidopsis
mutant brm-3, which is moderately defective in SWI2/SNF2 chromatin remodeling ATPase BRAHMA (BRM) activity, produced more PP2C gene transcripts under salt-stress conditions, indicating that BRM ATPase contributes to the
repression of PP2C gene transcription.
List of Participants
Aasumets Koit, [email protected], University of Tartu, Estonia
Akinyemi Olusegun, [email protected], Czech University of Life Sciences Prague & University of Eastern Finland
Alegre Sara, [email protected], University of Turku, Finland
Ali Bajwa Azfar, [email protected], University of Turku, Finland
Allahverdiyeva-Rinne Yagut, [email protected], University of Turku, Finland
Auzane Agate, [email protected], University of Helsinki, Finland
Balakhonova Veronika, [email protected], Masaryk University, Czech Republic
Battchikova Natalia, [email protected], University of Turku, Finland
Bayer Emmanuelle, [email protected], CNRS university of Bordeaux, France
Blajecka Karolina, [email protected], Sainsbury Laboratory University of Cambridge (SLCU), UK
Broholm Suvi, [email protected], Academy of Finland, Finland
Brosche Mikael, [email protected], University of Helsinki, Finland
Cheong Jong-Joo, [email protected], Seoul National University, South Korea
Christita Margaretta, [email protected], University of Helsinki, Finland
Citterico Matteo, [email protected], University of Helsinki, Finland
Dvořák Petr, [email protected], Palacky University Olomouc, Czech Republic
Ehonen Sanna, [email protected], University of Helsinki, Finland
Elomaa Paula, [email protected], University of Helsinki, Finland
Eva-Mari Aro, [email protected], University of Turku, Finland
Felicia Toussaint, [email protected], Rudn University, Moscow, Russia
Ferrari Simone, [email protected], University of Rome Sapienza, Italy
Fujii Hiroaki, [email protected], University of Turku, Finland
Garcia-Molina Antoni, [email protected], Ludwig-Maximilians University Munich (LMU), Germany
Gollan Peter, [email protected], University of Turku, Finland
Gossens Richard, [email protected], University of Helsinki, Finland
Grebe Steffen, [email protected], University of Turku, Finland
Gregory Franklin, [email protected], Institute of Plant Genetics of the Polish Academy of Sciences, Poznan, Poland
Guglielminetti Lorenzo, [email protected], University of Pisa, Italy
Havurinne Vesa, [email protected], University of Turku, Finland
Helariutta Yka, [email protected], University of Helsinki, Finland and Sainsbury Laboratory Cambridge University, UK
Himanen Kristiina, [email protected], University of Helsinki, Finland
Huarancca Reyes Thais, [email protected], University of Pisa, Italy
Hunter Kerri, [email protected], University of Helsinki, Finland
Iida Hiroyuki, [email protected], University of Helsinki, Finland
Ilievska Maja, [email protected], University of Helsinki, Finland
Immanen Juha, [email protected], Natural Resources Institute Finland (Luke), Helsinki, Finland
Israel David, [email protected], University of Helsinki, Finland
Jokel-Toivanen Martina, [email protected], University of Turku, Finland
Jokilehto Terhi, [email protected], University of Turku, Finland
Kallio Pauli, [email protected], University of Turku, Finland
Kalmbach Lothar, [email protected], Sainsbury Laboratory Cambridge University (SLCU)
Kangasjärvi Jaakko, [email protected], University of Helsinki, Finland
Kangasjärvi Saijaliisa, [email protected], University of Turku, Finland
Kerfeld Cheryl, [email protected], MSU-LBNL, USA
Khorobrykh Sergey, [email protected], University of Turku, Finland
Kollist Hannes, [email protected], University of Tartu, Estonia
Konopatskaia Irina, [email protected], Institute of Cytology and Genetics SB RAS, Russia
Koolmeister Kaspar, [email protected], Tartu University Institute of Technology, Estonia
Kosourov Sergey, [email protected], University of Turku, Finland
Krasensky-Wrzaczek Julia, [email protected], University of Helsinki, Finland
Krishnamoorthy Sivakumar, [email protected], Adam Mickiewicz University, Poznan, Poland
Kucukoglu Melis, [email protected], University of Helsinki, Finland
Kulshrestha Samarth, [email protected], University of Canterbury, New Zealand
Laitinen Roosa, [email protected], Max Planck Institute of Molecular Plant Physiology, Germany
Lamminmäki Airi, [email protected], University of Helsinki, Finland
Leal Gavarron Marina, [email protected], University of Helsinki, Finland
Lempiäinen Tapio, [email protected], University of Turku, Finland
Leonardelli Manuela, [email protected], University of Geneva, Switzerland
López Ortiz Jennifer, [email protected], University of Helsinki, Finland
Lyu Munan, [email protected], University of Helsinki, Finland
Matam Pradeep, [email protected], Institute of Plant Genetics of the Polish Academy of Sciences, Poznan, Poland
Mattila Heta, [email protected], University of Turku, Finland
Meigas Egon, [email protected], Tartu University Institute of Technology, Estonia
Meisrimler Claudia-Nicole, [email protected], University of Canterbury, New Zealand
Mullineaux Phil, [email protected], University of Essex, UK
Mulo Paula, [email protected], University of Turku, Finland
Muntazir Mehdi Syed Muhammad, [email protected], Adam Mickiewicz University, Poznan, Poland
Muranen Sampo, [email protected], University of Helsinki, Finland
Muth-Pawlak Dorota, [email protected], University of Turku, Finland
Mähönen Ari Pekka, [email protected], University of Helsinki, Finland
Mäkilä Riikka, [email protected], University of Helsinki, Finland
Nakayama Mayumi, [email protected], Tohoku University, Japan
Nieminen Kaisa, [email protected], Natural Resources Institute Finland (Luke), Helsinki, Finland
Nikkanen Lauri, [email protected], University of Turku, Finland
Nilsson Ove, [email protected], SLU, Sweden
Nowaczyk Marc, [email protected], Ruhr-University Bochum, Germany
Ort Donald, [email protected], University of Illinois, USA
Overmyer Kirk, [email protected], University of Helsinki, Finland
Pandey Ashutosh, [email protected], Tartu Institute of Technology, Estonia
Pareek Akanksha, [email protected], National Institute of Plant Genome Research, New Delhi, India
Patrikainen Pekka, [email protected], University of Turku, Finland
Pogson Barry, [email protected], Australian National University, Australia
Porcar-Castell Albert, [email protected], University of Helsinki, Finland
Raines Christine, [email protected], University of Essex, UK
Rantala Marjaana, [email protected], University of Turku, Finland
Rintamäki Eevi, [email protected], University of Turku, Finland
Robatzek Silke, [email protected], Ludwig-Maximilians University Munich (LMU), Germany
Roszak Pawel, [email protected], Sainsbury Laboratory Cambridge University (SLCU), UK
Ruonala Raili, [email protected], University of Helsinki, Finland
Safronov Omid, [email protected], University of Helsinki, Finland
Sampathkumar Arun, [email protected], Max Planck Institute for Molecular Plant Physiology, Germany
Schulman Alan, [email protected], LUKE/ BI Plant Genome Dynamics, University of Helsinki, Finland
Schwenner Naike, [email protected], University of Münster, Germany
Selvakesavan Rajendran Kamalabai, [email protected], Institute of Plant Genetics of the Polish Academy of Sciences,
Poznan, Poland
Sevilem Iris, [email protected], University of Helsinki, Finland
Shapiguzov Alexey, [email protected], University of Helsinki, Finland
Sims-Huopaniemi Karen, [email protected], University of Helsinki, Finland
Su Chang, [email protected], University of Helsinki, Finland
Teeri Teemu, [email protected], University of Helsinki, Finland
Tikkanen Mikko, [email protected], University of Turku, Finland
Tiwari Arjun, [email protected], University of Turku, Finland
Trotta Andrea, [email protected], University of Turku, Finland
Tyystjärvi Esa, [email protected], University of Turku, Finland
Vaattovaara Aleksia, [email protected], University of Helsinki, Finland
Vahisalu Triin, [email protected], University of Helsinki, Finland
Van Breusegem Frank, [email protected], Ghent University-VIB, Belgium
Van Wittenberghe Shari, [email protected], University of Helsinki, Finland
Wang Linping, [email protected], University of Helsinki, Finland
Wang Wei, [email protected], Swedish University of Agricultural Sciences, Sweden
Wang Xin, [email protected], University of Helsinki, Finland
Waszczak Cezary, [email protected], University of Helsinki, Finland
Vavilova Valeriya, [email protected], Institute of Cytology and Genetics SB RAS, Russia
Vázquez Jesús Pascual, [email protected], University of Turku, Finland
Virtanen Olli, [email protected], University of Turku, Finland
Wrzaczek Michael, [email protected], University of Helsinki, Finland
Wybouw Brecht, [email protected], University of Helsinki, Finland
Xu Shan, [email protected], INAR, University of Helsinki, Finland
Yarmolinsky Dmitry, [email protected], University of Tartu, Estonia
Zamora Olena, [email protected], University of Helsinki, Finland
Zhang Chao, [email protected], University of Helsinki, Finland
Zhang Jing, [email protected], University of Helsinki, Finland
Zhao Yafei, [email protected], University of Helsinki, Finland
Zhu Lingping, [email protected], University of Helsinki, Finland