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Growth regulators Auxins Cytokinins Gibberellins Abscisic Acid Ethylene Brassinoteroids Jasmonic Acid Salicylic Acid Strigolactones Nitric Oxide Sugars
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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)!
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Gibberellins GAs 1, 3 & 4 are most bioactive Made at many locations in plant Act by triggering degradation of DELLA repressors w/o GA DELLA binds & blocks activator bioactive GA binds GID1; GA-GID1 binds DELLA & marks for destruction GA early genes are transcribed, start GA responses
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Gibberellins & barley germination
GAs made by embryo diffuse to aleurone & trigger events leading to germination
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GA & stem elongation GA increase elongation, but lag >>> IAA
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GA & stem elongation GA increase elongation, but lag >>> IAA Increase cell wall creepage, but don't change pH (much)
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GA & stem elongation GA increase elongation, but lag >>> IAA Increase cell wall creepage, but don't change pH (much) Part of effect is increased expansin gene expression
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GA & stem elongation GA increase elongation, but lag >>> IAA Increase cell wall creepage, but don't change pH (much) Part of effect is increased expansin gene expression Another part is increased cell division
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Potential GA ncRNA signaling mutant?
Nearly ½ of human genome is transcribed, only 1% is coding 98% of RNA made is non-coding Fraction increases with organism’s complexity
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Incredible diversity of functions!
Epigenetic Directly regulating transcription Post-transcriptional regulation Some are made by Pol II, others by Pol III
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ncRNA mutants Extracted total RNA from a mix of tissues, separated by size and sequenced nt fraction
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ncRNA mutants Extracted total RNA from a mix of tissues, separated by size and sequenced nt fraction BLAST to find relatives (and discard tRNA, etc)
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ncRNA mutants Extracted total RNA from a mix of tissues, separated by size and sequenced nt fraction BLAST to find relatives (and discard tRNA, etc) T-DNA express to find mutants
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ncRNA mutants Extracted total RNA from a mix of tissues, separated by size and sequenced nt fraction BLAST to find relatives (and discard tRNA, etc) T-DNA express to find mutants ordered seeds for ones we found interesting
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ncRNA mutants Extracted total RNA from a mix of tissues, separated by size and sequenced nt fraction BLAST to find relatives (and discard tRNA, etc) T-DNA express to find Mutants 4. ordered seeds for ones we found interesting 5. Grew them and looked for ones that looked funny
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ncRNA mutants Grew them and looked for ones that looked funny
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ncRNA mutants Grew them and looked for ones that looked funny
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ncRNA mutants Grew them and looked for ones that looked funny Expression of flanking genes is not affected
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ncRNA mutants Grew them and looked for ones that looked funny Expression of flanking genes is not affected Next: add back wt ncRNA gene and see if “rescues” phenotype.
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GA & other hormones GA interacts w many other hormones t/o plant life cycle
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GA & other hormones GA interacts w many other hormones t/o plant life cycle + with auxin via DELLA & induction of GA synthesis
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GA & other hormones GA 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
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GA & other hormones GA 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
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ABA Discovered as inhibitor of auxin –induced elongation (inhibitor b). Also found lots in tissues going dormant (dormin) Also found chemicals from senescing leaves & fruits that accelerated leaf abscission (abscission II) Was abscisic acid
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ABA Counteracts GA effects Causes seed dormancy & inhibits seed germination Inhibits fruit ripening
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ABA Also made in response to many stresses. Most is made in root & transported to shoot
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ABA Most is made in root & transported to shoot in response to stress Closes stomates by opening Ca then closing K channels
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ABA Synthesized during seed maturation to promote dormancy Also closes stomates in stress by opening Ca then closing K channels Induces many genes (~10% of total) via several different mechs bZIP/ABRE (ABI3, 4, 5 + AREBs)
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ABA Synthesized during seed maturation to promote dormancy Also closes stomates in stress by opening Ca then closing K channels Induces many genes (~10% of total) via several different mechs bZIP/ABRE (ABI3, 4, 5 + AREBs) MYC/MYB
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ABA Induces many genes (~10% of total) via several different mechs bZIP/ABRE (ABI3, 4, 5 + AREBs) MYC/MYB Jae-Hoon Lee has found 3 DWA genes that mark ABI5 (but not MYC or MYB) for destruction
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Jae-Hoon Lee Found T-DNA insertions in DWD 3 were sensitive to ABA
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Jae-Hoon Lee Found T-DNA insertions in DWD proteins 3 were sensitive to ABA ABI5 was elevated in dwa mutants
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Jae-Hoon Lee Found T-DNA insertions in DWD proteins 3 were sensitive to ABA ABI5 was elevated in dwa mutants ABI5 was degraded more slowly in dwa extracts DWAs target ABI5 for degradation
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TAIZ-Zeiger version of ABA signaling
3 groups of receptors GTG in PM Resemble GPCR
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TAIZ-Zeiger version of ABA signaling
3 groups of receptors GTG in PM Resemble GPCR IP3 has role in ABA Unclear if GTG cause IP3 production
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TAIZ-Zeiger version of ABA signaling
3 groups of receptors GTG in PM CHLH in Cp Also catalyzes Chl synthesis
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TAIZ-Zeiger version of ABA signaling
3 groups of receptors GTG in PM CHLH in Cp Also catalyzes Chl synthesis And signals cp damage to nucleus
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TAIZ-Zeiger version of ABA signaling
3 groups of receptors GTG in PM CHLH in Cp PYR/PYL/RCAR cytoplasmic
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Schroeder version of ABA signaling
PYR/PYL/RCAR is key player Binds ABA& inactivates PP2C
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Schroeder version of ABA signaling
PYR/PYL/RCAR is key player Binds ABA& inactivates PP2C Allows SnRK2 to function
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Schroeder version of ABA signaling
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
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ABA signaling in Guard Cells
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Ethylene A gas that acts as a hormone! Chinese burned incense to ripen pears 1864: leaks from street lamps damage trees
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Ethylene A gas that acts as a hormone! Chinese burned incense to ripen pears 1864: leaks from street lamps damage trees Neljubow (1901): ethylene causes triple response: short stems, swelling & abnormal horizontal growth
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Ethylene A gas that acts as a hormone! Chinese burned incense to ripen pears 1864: leaks from street lamps damage trees Neljubow (1901): ethylene causes triple response: short stems, swelling & abnormal horizontal growth Doubt (1917): stimulates abscission Gane (1934): a natural plant product
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Ethylene Effects Climacteric fruits produce spike of ethylene at start of ripening & exogenous ethylene enhances this
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Ethylene Effects Climacteric fruits produce spike of ethylene at start of ripening & exogenous ethylene enhances this Results: 1) increased respiration 2) production of hydrolases & other enzymes involved in ripening
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Ethylene Effects Normally IAA from leaf tip keeps abscission zone healthy
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Ethylene Effects Normally IAA from leaf tip keeps abscission zone healthy When IAA abscission zone becomes sensitive to ethylene
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Ethylene Effects Normally IAA from leaf tip keeps abscission zone healthy When IAA abscission zone becomes sensitive to ethylene Ethylene induces hydrolases & leaf falls off
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Ethylene Synthesis Made in response to stress, IAA, or during ripening
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Ethylene Synthesis Made in response to stress, IAA, or during ripening Use ACC or ethephon (which plants convert to ethylene) to synchronize flowering, speed ripening
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Ethylene Synthesis Made in response to stress, IAA, or during ripening Use ACC or ethephon (which plants convert to ethylene) to synchronize flowering, speed ripening Recent work shows ACC has own effects
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Ethylene Synthesis Made in response to stress, IAA, or during ripening Use ACC or ethephon (which plants convert to ethylene) to synchronize flowering, speed ripening Recent work shows ACC has own effects Use silver & other inhibitors to preserve flowers & fruit
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Ethylene Signaling Receptors were identified by mutants in triple response
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Ethylene Signaling Receptors were identified by mutants in triple response Also resemble bacterial 2-component signaling systems!
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Ethylene Signaling Receptors were identified by mutants in triple response Also resemble bacterial 2-component signaling systems! Receptor is in ER!
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Ethylene Signaling 1. In absence of ethylene, receptors activate CTR1 which represses EIN2-dependent signaling
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Ethylene Signaling In absence of ethylene, receptors activate CTR1 which represses EIN2-dependent signaling Upon binding ethylene, receptors inactivate CTR1 by unknown mech
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Ethylene Signaling In absence of ethylene, receptors activate CTR1 which represses EIN2-dependent signaling Upon binding ethylene, receptors inactivate CTR1 by unknown mech 3. Active EIN2 activates EIN3
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Ethylene Signaling In absence of ethylene, receptors activate CTR1 which represses EIN2-dependent signaling Upon binding ethylene, receptors inactivate CTR1 by unknown mech 3. Active EIN2 activates EIN3 4. EIN3 turns on genes needed for ethylene response.
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Ethylene Signaling In absence of ethylene, receptors activate CTR1 which represses EIN2-dependent signaling Upon binding ethylene, receptors inactivate CTR1 by unknown mech 3. Active EIN2 activates EIN3 4. EIN3 turns on genes needed for ethylene response. 5. Ethylene receptor also turns off EIN3 degradation
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Jasmonates Fatty acid derivatives first discovered as growth inhibitors made by a fungus
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Jasmonates Fatty acid derivatives first discovered as growth inhibitors made by a fungus Subsequently found to be made by plants in response to stress
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Jasmonates Fatty acid derivatives mainly involved in stress signaling Also needed for pollen development Maturation Elongation of stamen filaments Dehiscence of anther locules
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Jasmonates Fatty acid derivatives mainly involved in stress signaling Also needed for pollen development JAZ proteins block TF until bind JA
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Jasmonates Fatty acid derivatives mainly involved in stress signaling Also needed for pollen development JAZ proteins block TF until bind JA Degraded when JA is present COI1 = E3 receptor for JAZ
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Jasmonates Fatty acid derivatives mainly involved in stress signaling Also needed for pollen development JAZ proteins block TF until bind JA Degraded when JA is present COI1 = E3 receptor for JAZ JA genes are transcribed Control pollen development & other cellular effects
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Jasmonates Fatty acid derivatives mainly involved in stress signaling Also needed for pollen development JAZ proteins block TF until bind JA Degraded when JA is present COI1 = E3 receptor for JAZ JA genes are transcribed Control pollen development & other cellular effects, including trichome development
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