growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinoteroids
DESCRIPTION
Growth regulators Auxins Cytokinins Gibberellins Abscisic Acid Ethylene Brassinoteroids Jasmonic Acid Salicylic Acid Strigolactones Nitric Oxide Sugars. Gibberellins "rescued" some dwarf corn & pea mutants Made rosette plants bolt Trigger adulthood in ivy & conifers - PowerPoint PPT PresentationTRANSCRIPT
Growth regulators1.Auxins 2.Cytokinins 3.Gibberellins 4.Abscisic Acid 5.Ethylene 6.Brassinoteroids 7.Jasmonic Acid 8.Salicylic Acid 9.Strigolactones 10.Nitric Oxide 11.Sugars
Gibberellins• "rescued" some dwarf corn & pea mutants• Made rosette plants bolt• Trigger adulthood in ivy & conifers• Induce growth of seedless fruit• Promote seed germination• Inhibitors shorten stems: prevent lodging• >136 gibberellins (based on structure)!
GibberellinsGAs 1, 3 & 4 are most bioactiveMade at many locations in plantAct by triggering degradation of DELLA repressorsw/o GA DELLA binds & blocks activatorbioactive GA binds GID1;GA-GID1 binds DELLA& marks for destructionGA early genes are transcribed, start GA responses
GA & other hormonesGA interacts w many other hormones t/o plant life cycle
GA & other hormonesGA interacts w many other hormones t/o plant life cycle+ with auxin via DELLA & induction of GA synthesis
GA & other hormonesGA interacts w many other hormones t/o plant life cycle+ with auxin via DELLA & induction of GA synthesis- with cytokinins via reciprocal effects on synthesis
GA & other hormonesGA interacts w many other hormones t/o plant life cycle+ with auxin via DELLA & induction of GA synthesis- with cytokinins via reciprocal effects on synthesis- with ABA via Myb & DELLA
ABADiscovered as inhibitor of auxin –induced elongation (inhibitor ).Also found lots in tissues going dormant (dormin)Also found chemicals from senescing leaves & fruits that accelerated
leaf abscission (abscission II)
Was abscisic acid
ABACounteracts GA effects• Causes seed dormancy &
inhibits seed germination• Inhibits fruit ripening
ABAAlso made in response to many stresses.Most is made in root & transported to shoot
ABAMost is made in root & transported to shoot in response to stressCloses stomates by opening Ca then closing K channels
ABASynthesized during seed maturation to promote dormancyAlso closes stomates in stress by opening Ca then closing K channelsInduces many genes (~10% of total) via several different mechs1. bZIP/ABRE (ABI3, 4, 5 + AREBs)
ABASynthesized during seed maturation to promote dormancyAlso closes stomates in stress by opening Ca then closing K channelsInduces many genes (~10% of total) via several different mechs1. bZIP/ABRE (ABI3, 4, 5 + AREBs)2. MYC/MYB
ABAInduces many genes (~10% of total) via several different mechs1. bZIP/ABRE (ABI3, 4, 5 + AREBs)2. MYC/MYB Jae-Hoon Lee has found 3 DWA genes that mark ABI5 (but not
MYC or MYB) for destruction
TAIZ-Zeiger version of ABA signaling3 groups of receptors1. GTG in PM• Resemble GPCR
TAIZ-Zeiger version of ABA signaling3 groups of receptors1. GTG in PM• Resemble GPCR• IP3 has role in ABA• Unclear if GTG causeIP3 production
TAIZ-Zeiger version of ABA signaling3 groups of receptors1. GTG in PM2. CHLH in Cp• Also catalyzes Chl synthesis
TAIZ-Zeiger version of ABA signaling3 groups of receptors1. GTG in PM2. CHLH in Cp• Also catalyzes Chl synthesis• And signals cp damage to nucleus
TAIZ-Zeiger version of ABA signaling3 groups of receptors1. GTG in PM2. CHLH in Cp3. PYR/PYL/RCAR• cytoplasmic
Schroeder version of ABA signaling1. PYR/PYL/RCAR is key player• Binds ABA& inactivates PP2C
Schroeder version of ABA signaling1. PYR/PYL/RCAR is key player• Binds ABA& inactivates PP2C• Allows SnRK2 to function
Schroeder version of ABA signaling1. PYR/PYL/RCAR is key player• Binds ABA& inactivates PP2C• Allows SnRK2 to function• SnRK2 then kinases many targets, including ion channels, TFs &
ROS producers
ABA signaling in Guard Cells
EthyleneA gas that acts as a hormone!Chinese burned incense to ripen pears1864: leaks from street lamps damage treesNeljubow (1901): ethylene causes triple response: short stems,
swelling & abnormal horizontal growth
EthyleneA gas that acts as a hormone!Chinese burned incense to ripen pears1864: leaks from street lamps damage treesNeljubow (1901): ethylene causes triple response: short stems,
swelling & abnormal horizontal growthDoubt (1917): stimulates abscissionGane (1934): a naturalplant product
Ethylene EffectsClimacteric fruits produce spike of ethylene at start of ripening &
exogenous ethylene enhances this
Ethylene EffectsClimacteric fruits produce spike of ethylene at start of ripening &
exogenous ethylene enhances thisResults: 1) increased respiration2) production of hydrolases & other enzymes involved in ripening
Ethylene EffectsNormally IAA from leaf tip keeps abscission zone healthy
Ethylene EffectsNormally IAA from leaf tip keeps abscission zone healthyWhen IAA abscission zone becomes sensitive to ethylene
Ethylene EffectsNormally IAA from leaf tip keeps abscission zone healthyWhen IAA abscission zone becomes sensitive to ethyleneEthylene induces hydrolases & leaf falls off
Ethylene SynthesisMade in response to stress, IAA, or during ripening
Ethylene SynthesisMade in response to stress, IAA, or during ripeningUse ACC or ethephon (which plants convert to ethylene) to synchronize flowering, speedripening
Ethylene SynthesisMade in response to stress, IAA, or during ripeningUse ACC or ethephon (which plants convert to ethylene) to synchronize flowering, speedripening• Recent workshows ACC has own effects
Ethylene SynthesisMade in response to stress, IAA, or during ripeningUse ACC or ethephon (which plants convert to ethylene) to synchronize flowering, speedripening• Recent workshows ACC has own effects• Use silver & other inhibitors to preserve flowers & fruit
Ethylene SignalingReceptors were identified by mutants in triple response
Ethylene SignalingReceptors were identified by mutants in triple responseAlso resemble bacterial 2-component signaling systems!
Ethylene SignalingReceptors were identified by mutants in triple responseAlso resemble bacterial 2-component signaling systems!Receptor is in ER!
Ethylene Signaling1. In absence of ethylene, receptors activate CTR1 which represses
EIN2-dependent signaling
Ethylene Signaling1. In absence of ethylene, receptors activate CTR1 which represses
EIN2-dependent signaling2. Upon binding ethylene, receptorsinactivate CTR1 by unknown mech
Ethylene Signaling1. In absence of ethylene, receptors activate CTR1 which represses
EIN2-dependent signaling2. Upon binding ethylene, receptorsinactivate CTR1 by unknown mech3. Active EIN2 activates EIN3
Ethylene Signaling1. In absence of ethylene, receptors activate CTR1 which represses
EIN2-dependent signaling2. Upon binding ethylene, receptorsinactivate CTR1 by unknown mech3. Active EIN2 activates EIN34. EIN3 turns on genes needed for ethylene response.
Ethylene Signaling1. In absence of ethylene, receptors activate CTR1 which represses
EIN2-dependent signaling2. Upon binding ethylene, receptorsinactivate CTR1 by unknown mech3. Active EIN2 activates EIN34. EIN3 turns on genes needed for ethylene response.5. Ethylene receptor also turns off EIN3 degradation