game plan we will study effects of elevated co 2 and temperature on flowering time and see where it...

Game planWe will study effects of elevated CO2 and temperature on flowering time and see where it takes us.1. Learn more about how plants choose when to flower

Game planWe will study effects of elevated CO2 and temperature on flowering time and see where it takes us.1. Learn more about how plants choose when to flower•Environmental influences on flowering


2. Pick some plants to study


2. Pick some plants to study3. Get them growing


2. Pick some plants to study3. Get them growing4. Design some experiments for other things to test before they start flowering

Game planSuggestions

1.Arabidopsis 2. Fast plant3. Sorghum 4. Brachypodium distachyon5. Amaranthus 6. Quinoa7. Kalanchoe 8. Venus fly traps

Options1.Pick several plants



Options1.Pick several plants• C3, C4, CAM



Options1.Pick several plants• C3, C4, CAM• Long Day, short day, Day neutral



Options1.Pick several plants• C3, C4, CAM• Long Day, short day, Day neutral• Tropical, temperate, arctic



Options1.Pick several plants• C3, C4, CAM• Long Day, short day, Day neutral• Tropical, temperate, arctic• ?????




2.Pick one plant1. Study many conditions


2.Pick one plant• Study many conditions• Study many variants/mutants• ?????

Grading?Combination of papers, presentations & lab reports• 4 lab reports @ 2.5 points each• 5 assignments @ 2 points each• Presentation on global change and plants: 5 points • Research proposal: 10 points • Final presentation: 15 points • Poster: 10 points• Draft report 10 points• Final report: 30 points

Assignment 11.Pick a plant that might be worth studying•Try to convince the group in 5-10 minutes why yours is best: i.e., what is known/what isn’t known

Plant Growth & DevelopmentOccurs in 3 stages1. Embryogenesis

From fertilization to seed2. Vegetative growth

Juvenile stageFrom seed germination to adult"phase change" marks transition

3. Reproductive developmentStart making flowers, can reproduce sexually

Transition to Adult PhaseJuveniles & adults are very different!

Transition to FloweringAdults are competent to flower, but need correct signalsVery complex process!Can be affected by:• Daylength• Temperature (especially cold!)• Water stress• Nutrition• Hormones

Early StudiesJulius Sachs (1865) first proposed florigen Garner and Allard (1920) discovered photoperiodismMaryland Mammoth tobacco flowers in the S but not in NKnott (1934) day length is perceived by the leaves

Early StudiesKnott (1934) day length is perceived by the leaves• Flowers are formed at SAM!• Florigen moves from leaves to SAM• Is graft-transmissable!• Moves in phloem

ComplicationsSome plants are qualitative (must have correct daylength),

others are quantitative (correct days speed flowering)Four pathways control flowering:

1. Photoperiod• PHY only• PHY + CRY

2. Vernalization: requires cold period3. gibberellin (GA)4. Autonomous

ComplicationsFlorigen is “universal”: transmitted from LDP to SDP and

vice-versa via graftsSolved by identifying genes that control flowering time

Genes controlling floweringFlorigen is “universal”: transmitted from LDP to SDP and


1. CONSTANS (CO): co mutants are day-length insensitive & flower late



1. CONSTANS (CO): co mutants are day-length insensitive & flower late• CO mRNA is expressed in leaf but not SAM &

increases in LD




increases in LD• CO encodes a ZN-finger transcription factor

(TF) that induces expression of FLOWERING LOCUS T (FT)




increases in LD• CO encodes a ZN-finger TF that induces

expression of FLOWERING LOCUS T (FT)2. FLOWERING LOCUS T (FT): a strong promoter

of flowering




increases in LD• CO encodes a ZN-finger TF that induces

expression of FLOWERING LOCUS T (FT)2. FLOWERING LOCUS T (FT): a strong promoter

of flowering: encodes a RAF kinase inhibitor protein

Genes controlling flowering1. CONSTANS (CO): co mutants are day-length

insensitive & flower late2. FLOWERING LOCUS T (FT): a strong promoter of

flowering: encodes a RAF kinase inhibitor protein3. FLOWERING LOCUS C (FLC): a MADS-box gene

strongly represses flowering

http://en.wikipedia.org/wiki/MADS-box




strongly represses flowering• Highly expressed in non-vernalized tissues





strongly represses flowering• Highly expressed in non-vernalized tissues• Turned off by vernalization due to chromatin mod





strongly represses flowering• Highly expressed in non-vernalized tissues• Turned off by vernalization due to chromatin mod

4. SUPPRESSOR OF CONSTANS 1 (SOC1): a MADS-BOX TF that activates genes for floral development.


Transition to floweringUpon induction, CO activates transcription of FT in leavesFT protein moves from leaves to shoot apex in phloem!

Transition to floweringUpon induction, CO activates transcription of FT in leavesFT protein moves from leaves to shoot apex in phloem!In SAM combines with FD to activate SOC1 & AP1

Transition to floweringUpon induction, CO activates transcription of FTFT protein moves from leaves to shoot apex in phloem!In SAM combines with FD to activate SOC1 &AP1These activate LFY &Flower genes

Transition to floweringUpon induction, CO activates transcription of FTFT protein moves from leaves to shoot apex in phloem!In SAM combines with FD to activate SOC1 &AP1These activate LFY &Flower genesOther signals convergeOn SOC1, either Directly or via FLC

SDPRice homolog to CO is Hd1Inhibits expression of Hd3a(the FT homolog)

SDPRice homolog to CO is Hd1Inhibits expression of Hd3a(the FT homolog) Induced by long days

SDPRice homolog to CO is Hd1Inhibits expression of Hd3a(the FT homolog) Induced by long daysOnly make Hd3a protein under short days

Transition to floweringEventually start flowering• Are now adults!• Time needed varies from days to years. • Shoot apical meristem now starts making new organ:

flowers, with many new structures & cell types

WATER• Plants' most important chemical• most often limits productivity


• Often >90%% of a plant cell’s weight


• Often >90%% of a plant cell’s weight• Gives cells shape


• Often >90%% of a plant cell’s weight• Gives cells shape• Dissolves many chem

WATER• Dissolves many chem• most biochem occurs in water• Source of e- for PS

WATER• most biochem occurs in water• Source of e- for PS• Constantly lose water due to PS (1000 H2O/CO2)

WATER• most biochem occurs in water• Source of e- for PS• Constantly lose water due to PS• Water transport is crucial!

WATER• Water transport is crucial!• SPAC= Soil Plant Air Continuum• moves from soil->plant->air

WATER Formula = H2O Formula weight = 18 daltons Structure = tetrahedron, bond angle 104.5˚

WATER Structure = tetrahedron, bond angle 104.5˚ polar :O is more attractive to electrons than H

+ on H- on O

WaterPolarity is reason for water’s properties water forms H-bonds with polar molecules

WaterPolarity is reason for water’s properties water forms H-bonds with polar molecules

Hydrophilic = polar moleculesHydrophobic = non-polar molecules

Properties of water1) Cohesion = water H-bonded to water

-> reason for surface tension

Properties of water1) Cohesion = water H-bonded to water

-> reason for surface tension-> why water can be drawn from roots to leaves

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else• Cohesion and adhesion are crucial for water movement in plants!

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else• Cohesion and adhesion are crucial for water movement in plants!• Surface tension & adhesion in mesophyll creates force that draws water through the plant!

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else3) high specific heat• absorb heat when break H-bonds: cools leaves

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else3) high specific heat• absorb heat when break H-bonds• Release heat when form H-bonds

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else3) high specific heat4) Ice floats

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else3) high specific heat4) Ice floats5) Universal solvent

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else3) high specific heat4) Ice floats5) Universal solvent•Take up & transport nutrients dissolved in water

Properties of water5) “Universal” solvent•Take up & transport nutrients dissolved in water•Transport organics dissolved in water

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else3) high specific heat4) Ice floats5) Universal solvent6) Hydrophobic bonds

Properties of water1) Cohesion = water H-bonded to water2) Adhesion = water H-bonded to something else3) high specific heat4) Ice floats5) Universal solvent6) Hydrophobic bonds7) Water ionizes

pH[H+] = acidity of a solutionpH = convenient way to measure aciditypH = - log10 [H+]pH 7 is neutral: [H+] = [OH-]

-> at pH 7 [H+] = 10-7 moles/l

pHPlants vary pH to control many processes!

Water movementDiffusion: movement of single molecules down ∆[ ] due to random motion until [ ] is even•Driving force?

Water movementDiffusion: movement of single molecules down ∆[ ] due to random motion until [ ] is even • Driving force: lowers free energy•∆G = ∆H- T∆S

Water movementDiffusion: movement of single molecules down ∆[ ] due to random motion until [ ] is even Bulk Flow: movement of groups ofmolecules down a pressure gradient

Water movementDiffusion: movement of single molecules down ∆[ ] due to random motion until [ ] is even Bulk Flow: movement of groups ofmolecules down a pressure gradient• Independent of ∆ [ ] !

Water movementDiffusion: movement of single molecules down ∆[] due to random motion until [ ] is even Bulk Flow: movement of groups of molecules down a pressure gradient•Independent of ∆[ ] !•How water moves through xylem

Water movementDiffusion: movement of single molecules down [] due to random motion until [ ] is even Bulk Flow: movement of groups of molecules down a pressure gradient•Independent of ∆ [ ] !•How water moves through xylem•How water moves through soil and apoplast

Water movementBulk Flow: movement of groups of molecules down a pressure gradient•Independent of ∆ [ ] !•How water moves through xylem•Main way water moves through soil and apoplast•Very sensitive to radius of vessel: increases as r4

Water movementDiffusion: movement of single molecules down ∆[] due to random motion until [ ] is even Bulk Flow: movement of groups of molecules down a pressure gradient•Independent of ∆[ ] !•How water moves through xylem•Main way water moves through soil and apoplast•Very sensitive to radius of vessel: increases as r4

Osmosis: depends on bulk flow and diffusion!

Water movementOsmosis: depends on bulk flow and diffusion!water crosses membranes but other solutes do notwater tries to even its [ ] on each side

Water movementOsmosis: depends on bulk flow and diffusion!water crosses membranes but other solutes do notwater tries to even its [ ] on each sideother solutes can’t: result is net influx of water

Water movementOsmosis: depends on bulk flow and diffusion!•Moves through aquaporins, so rate depends on pressure and [ ] gradients!

Water movementOsmosis: depends on bulk flow and diffusion!•Moves through aquaporins, so rate depends on pressure and [ ] gradients!• Driving force = water's free energy (J/m3 = MPa)

Water potentialDriving force = water's free energy = water potential w

• Important for many aspects of plant physiology


Water moves to lower its potential


Water moves to lower its potentialDepends on:

1. [H2O]: s (osmotic potential)

Water potentialWater moves to lower its potentialDepends on:


2. Pressure : p

• Turgor pressure inside cells

Water potentialWater moves to lower its potentialDepends on:


2. Pressure : p

• Turgor pressure inside cells• Negative pressure in xylem!

Water potentialWater moves to lower its potentialDepends on:• [H2O]: s (osmotic potential)

• Pressure p

• Gravity g

w = s +p + g

Water potentialWater moves to lower its potentialDepends on:• [H2O]: s (osmotic potential)

• Pressure p

• Gravity g

w = s +p + g

w of pure water at sea level

& 1 atm = 0 MPA

Water potentialw = s +p + g

w of pure water at sea level & 1 atm = 0 MPA

s (osmotic potential) is always negative



s (osmotic potential) is always negative• If increase [solutes] water will move in




p (pressure potential) can be positive or negative





• Usually positive in cells to counteract s

Water potentialp (pressure potential) can be positive or negative


• Helps plants stay same size despite daily fluctuations in w





• p in xylem is negative, draws water upwards





• p in xylem is negative, draws water upwardsg can usually be ignored, but important for tall trees

game plan we will study effects of elevated co 2 and temperature on flowering time and see where it...

Documents

short day

camlong day

day neutraltropical

venus fly trapsoptionspick

fast plant3

brachypodium distachyon5

effects of elevated

flowering time