systemic signal transduction in plants to the pathogen and herbivore

PAT 804-MOLECULAR BASIS OF HOST PATHOGEN INTERACTION(2+1)

Course Teacher Dr.K.Eraivan Arutkani Aiyanathan

Professor(Plant pathology)

“Plants faces challenges from various herbivores and micro organisms at all stages in all organs”

Plants are resistant to most potential pathogens in most!!!Because plants have evolved defense systems to protect themselves !!!

“ Systemic signal transduction in plants to the

Pathogen and Herbivore”

By ELANGO.K ID.No: 2016800505

Signal transduction

Signal Transduction

Any function that conveys some

information

To forward the information

to other- Intra cellular signal transduction-Inter cellular signal transduction- Systemic signal transduction

“ The transmission of molecular signals from the exterior of the cell to the interior is called signal transduction ”

Signal transduction

- Hildebrand,1970

Discovery of “G protein” and their role in signal transduction

The Nobel Prize in Medicine - 1994

Reception

Transduction

Response

Signal transduction pathway

OVER ALL VIEW OF SIGNAL TRANSDUCTION PROCESS

A signal molecule binds to a receptor protein, causing it to change shape.

Most signal receptors are plasma membrane proteins

Ligand – a molecule that attaches to another molecule due to complimentary shape and chemical nature

When the signal molecule attaches, the receptor undergoes a conformational change (allosteric change) and its shape changes.

Reception

Relay molecules called second messengers become activated and start a series of reactions in the cytoplasm.

Reactions get more intense at each step and are called a cascade.

TRANSDUCTION

Signal moleculeReceptor

CytoplasmSecondary messengers

Nucleus

Final molecule- lead to a nuclear response and cytoplasmic response within the cell.

Regulate gene expression in the nucleus by turning a gene on or off.

Activate an enzyme to catalyze a specific chemical reaction. Open or close a gated channel protein within the cell

membrane.

CELLULAR RESPONSE

Signal transduction

pathway

Systemic signal transduction in plants - Pathogens

Systemic signal molecules

Oligogalacturonides

Salicylic acid Systemin Jasmonic acid Fatty acids Abscisic acid Ethylene

Oligogalacturonides

Oligogalacturonides (OGAs) derived from pectic polysaccharides of plant cell walls have also been known to act as elicitor molecules.

OGAs have been shown to induce biosynthesis of phytoalexins in the cotyledons of soybean and kidney bean , proteinase inhibitors in tomato leaves and lignification of cucumber cotyledons and cultured castor bean cells.

OGA do not induce the hypersensitive reaction (HR) leading to cell death.

Injury of one leaf induces in neighboring uninjured leaves of the same plant a defense response - synthesizing proteinase inhibitor (PI) proteins

Released at the site of injury is capable of moving to other leaves- proteinase inhibitor inducing factor (PIIF)

Pectic polysaccharides and oligosaccharides derived by partial enzymic hydrolysis of them evoked the synthesis of PI

Mobile wound-hormones The oligosaccharide molecules associated with

membrane receptors and with changes in protein phosphorylation patterns of membranes and cellular proteins during the induction process.

Oligogalacturonides

(Shibuya and Minami, 2001)

(Shibuya and Minami, 2001)

Salicylic acid

SA/orthohydroxy benzoic acid- group of phenolics Induced resistance becomes systemic SAR- endogenous signal produced by infected leaf and

translocate in the phloem to other plant parts Vascular mobile signal that moves throughout the plant

after initial infection It is reported in several plant species like tomato, potato,

pea, sunflower etc. Salicylate regulated defenses more active against

biotrophic pathogens

SA meets the essential criteria of a signal molecule

SA induces resistance to pathogens

SA induces PR proteins

SA levels increase locally and systemically following pathogen attack

SA moves throughout the plant via phloem

Young potato leaves with enhanced levels of salicylic acid are less susceptible to P. infestans than older leaves.

In Arabidopsis and to a lesser extent, acetyl salicylic acid are able to induce resistance against Alternaria solani and Erysiphe cichoracearum in potato

Salicylic acid on tobacco plants role in mediating genetically- determined resistance, significantly reduced blue mold disease

Salicylic acid

(Bokshi et al., 2003).

Systemin

Plant peptide hormone involved in the wound response in the Solanaceae family.

Isolated- tomato leaves in 1991 by a group lead by Clarence A. Ryan

Systemin induces the production of protease inhibitors which protect against insect herbivores, other peptides activate defensins and modify root growth.

Systemin

Jasmonic acid

JA was first isolated from cultures of the fungus Lasiodiplodia theobromae

Derivatives of JA - tuberonic acid and cucurbic acid Tuberonic acid regulate tuber formation in potato The highest levels of JA/JAMe are reported in flowers

and reproductive tissues and lower levels are found in roots and mature leaves

JA - 10ng to as much as 3μg/g fresh weight in different tissues

Jasmonate regulated defenses more active against necrotrophic pathogens

(Ballare, 2014)

Ethylene also induces systemic resistance and modulates gene expression at the post transcriptional level, suggesting a rule as a downstream modulator of response initiated by elicitor-induced transcriptional activation

Derived from methionine and involved in physiological process

Exogenous application of ethylene to tobacco carrying the N gene for resistance to TMV.

It induce some of the PRs- β 1,3 glucanase and chitinase

Ethylene

Abscisic acid It is the key factor in the systemic induction of

proteinase inhibitor genes.

Fatty acids: Plant lipoxygenases- important role in defense

mechanisms against pathogens Linoleic and linolenic acids Lipoxygenase products of these fatty acids are

metabolized to compounds that may function as signal molecules.

Methyl jasmonate, the important systemic signal molecule, is formed due to the action of lipoxygenase.

Another signal molecule, traumatin, is also synthesized by action of lipoxygenase.

Defense Proteins

Salicylic Acid

The plant defense proteins provide

the plant resistance to a variety of plant

pathogens.

Disease organisms and nonpathogenic microbes stimulates the plant above or

belowground to produce the

hormone salicylic acid.

An increase in the hormone salicylic acid

causes the plant to produce many types of pant defense proteins.

Plant hormones Jasmonate and

Ethylene increase throughout the

plant and induce resistance to a wide

variety of plant pathogens.

Jasmonate

Ethylene

Plant growth promoting

rhizobacteria (PGPR) stimulate plants roots, causing

production of plant defense hormones

ISRInduced Resistance

SARInduced Resistance

a) Systemic Acquired Resistance

b) Induced Systemic Resistance

(Vallad and Goodman , 2006)

Systemic signal transduction in plants - Herbivores

Recognition of Insect Herbivore Attack

Plants have the ability to distinguish between herbivores and mechanical damage, such as hail and wind, as well as to recognize ovipositioning

This feature is needed to avoid wasting expensive defense resources, since production and release of defense responses only benefits herbivore-challenged plants

Recognition of Insect Herbivore Attack

Herbivore-associated molecular patterns (HAMPs)

Insect Oral Secretions Ovipositional

Fluids

(Bonaventure et al., 2011)

Insect Oral Secretions

Plants are able to recognize compounds in insect oral secretions, which elicit more intense defense responses

Compared with the vast diversity of herbivores that attack plants, very few herbivore-derived elicitors are known

Conjugation of plant and herbivore-derived precursors result in the formation of fatty acid-amino acid conjugates (FACs)

Herbivore-associated elicitors

(Bonaventure et al., 2011)

Oviposition Fluids

Insect oviposition fluids can give rise to defense responses in the plant

Many female adult herbivorous insects lay eggs directly into plants, and some species are known to perceive insects oviposition activities and deploy defenses responses

Oviposition-induced plant responses acting against the herbivores

( Hilker and Meiners, 2006 )

( Hilker and Meiners, 2006 )

Oviposition-induced plant responses acting against the herbivores

Early Events in the Plant defense

Successful implementation of an induced defense response requires that plants respond to herbivory both rapidly and accurately

Early signaling events at the plant-insect interface, which occur well before changes in host plant gene expression and defense-related metabolism

( Mohanta et al., 2012 )

In plants attacked by insect herbivores, the expression of several defense genes is induced in undamaged leaves

Several components have been identified that are involved in the systemic induction of defense responses

- Systemin peptides - Oligogalacturonides (OGAs) - Jasmonates


Jasmonic acid

Novel plant immune hormone derived from α- linolenic acid.

Methyl Jasmonate was first time isolated from the essential oil of Jasminum grandiflorum.

Ubiquitous in plant kingdom and also produced by certain fungi (Lasiodiplodia theobromae).

Regulation of Defense Responses

Levels of jasmonic acid rise in response to herbivore damage

This hormone can trigger many types of plant defenses including bioactive compounds

The action of jasmonic acid induces the transcription of many genes involved in plant defense

Jasmonic acid turns on genes for proteinase inhibitor.

(Ballare, 2014)

Regulation of Defense Responses

Volatile compounds released by plants

(Pare and Tumlinson, 1999)

Plant Volatiles act as signal

Plant is damaged by herbivorous insects, many volatiles are released.

volatile compounds varies with the plant species. They may also induce defense responses in

neighbouring plants. Such chemicals, which function in communication

between and among species, as well as those that serve as messengers between members of the same species, are called semiochemicals.

( Cipollini and Heil, 2010)

Herbivore-induced plant volatiles (HIPV)HIPVs Plant Herbivore Natural Enemy

β-caryophyllene β-ocimene

Tobacco H. virescens Cardiochiles nigriceps

(E)-β-farnesene (E)-caryophyllene (E)-α-bergamotene

Maize S. littoralis Cotesia marginiventris

(E)–4,8–dimethyl-1,3,7-nonatriene

Maize M. separata Exorista japonica

Cotesia kariyai

linalool α-pinene 1-hexanol

Maize M. separata Exorista japonica

Campoletis chlorideae (Rodrigues et al., 2014)

Model of defense priming in plant -herbivore

interactions

(Frost et al., 2008)

Jasmonic acid & sallicylic acid pathway can be effectively use in biotic &abiotic stress resistance development.

Jasmonic acid & sallicylic acid cascades helps in understanding specific host pathogen interaction strategy .

It can be used in enhancing nutrient uptake under stress condition

It can help in proper growth and development activating factor.

CONCLUSION

“In future, there is need to obtain higher crop yields to fulfill demand of increasing population. It might be achieved by increasing the pathogen/insect resistance by manipulating the expression of the key genes involved in JA biosynthesis and signaling cascades”.

Future perspective

THANK YOU…. By

ELANGO.K

Nature has blessed me with Defense mechanism

systemic signal transduction in plants to the pathogen and herbivore

Education