Growth regulators 1 Auxins 2 Cytokinins 3 Gibberellins
Growth regulators 1. 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)!
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 GID 1; GA-GID 1 binds DELLA & marks for destruction GA early genes are transcribed, start GA responses
Gibberellins & barley germination GAs made by embryo diffuse to aleurone & trigger events leading to germination
GA & stem elongation GA increase elongation, but lag >>> IAA
GA & stem elongation GA increase elongation, but lag >>> IAA Increase cell wall creepage, but don't change p. H (much)
GA & stem elongation GA increase elongation, but lag >>> IAA Increase cell wall creepage, but don't change p. H (much) Part of effect is increased expansin gene expression
GA & stem elongation GA increase elongation, but lag >>> IAA Increase cell wall creepage, but don't change p. H (much) Part of effect is increased expansin gene expression Another part is increased cell division
Potential GA nc. RNA 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
Incredible diversity of functions! • Epigenetic • Directly regulating transcription • Post-transcriptional regulation Some are made by Pol II, others by Pol III
nc. RNA mutants 1. Extracted total RNA from a mix of tissues, separated by size and sequenced 50 -300 nt fraction
nc. RNA mutants 1. Extracted total RNA from a mix of tissues, separated by size and sequenced 50 -300 nt fraction 2. BLAST to find relatives (and discard t. RNA, etc)
nc. RNA mutants 1. Extracted total RNA from a mix of tissues, separated by size and sequenced 50 -300 nt fraction 2. BLAST to find relatives (and discard t. RNA, etc) 3. T-DNA express to find mutants
nc. RNA mutants 1. Extracted total RNA from a mix of tissues, separated by size and sequenced 50 -300 nt fraction 2. BLAST to find relatives (and discard t. RNA, etc) 3. T-DNA express to find mutants 4. ordered seeds for ones we found interesting
nc. RNA mutants 1. Extracted total RNA from a mix of tissues, separated by size and sequenced 50 -300 nt fraction 2. BLAST to find relatives (and discard t. RNA, etc) 3. T-DNA express to find Mutants 4. ordered seeds for ones we found interesting 5. Grew them and looked for ones that looked funny
nc. RNA mutants Grew them and looked for ones that looked funny
nc. RNA mutants Grew them and looked for ones that looked funny
nc. RNA mutants Grew them and looked for ones that looked funny • Expression of flanking genes is not affected
nc. RNA mutants Grew them and looked for ones that looked funny • Expression of flanking genes is not affected • Next: add back wt nc. RNA gene and see if “rescues” phenotype.
GA & other hormones GA interacts w many other hormones t/o plant life cycle
GA & other hormones GA interacts w many other hormones t/o plant life cycle + with auxin via DELLA & induction of GA synthesis
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
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
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
ABA Counteracts GA effects • Causes seed dormancy & inhibits seed germination • Inhibits fruit ripening
ABA Also made in response to many stresses. Most is made in root & transported to shoot
ABA Most is made in root & transported to shoot in response to stress Closes stomates by opening Ca then closing K channels
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 1. b. ZIP/ABRE (ABI 3, 4, 5 + AREBs)
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 1. b. ZIP/ABRE (ABI 3, 4, 5 + AREBs) 2. MYC/MYB
ABA Induces many genes (~10% of total) via several different mechs 1. b. ZIP/ABRE (ABI 3, 4, 5 + AREBs) 2. MYC/MYB Jae-Hoon Lee has found 3 DWA genes that mark ABI 5 (but not MYC or MYB) for destruction
Jae-Hoon Lee Found T-DNA insertions in DWD • 3 were sensitive to ABA
Jae-Hoon Lee • Found T-DNA insertions in DWD proteins • 3 were sensitive to ABA • ABI 5 was elevated in dwa mutants
Jae-Hoon Lee • Found T-DNA insertions in DWD proteins • 3 were sensitive to ABA • ABI 5 was elevated in dwa mutants • ABI 5 was degraded more slowly in dwa extracts • DWAs target ABI 5 for degradation
TAIZ-Zeiger version of ABA signaling 3 groups of receptors 1. GTG in PM • Resemble GPCR
TAIZ-Zeiger version of ABA signaling 3 groups of receptors 1. GTG in PM • Resemble GPCR • IP 3 has role in ABA • Unclear if GTG cause IP 3 production
TAIZ-Zeiger version of ABA signaling 3 groups of receptors 1. GTG in PM 2. CHLH in Cp • Also catalyzes Chl synthesis
TAIZ-Zeiger version of ABA signaling 3 groups of receptors 1. GTG in PM 2. CHLH in Cp • Also catalyzes Chl synthesis • And signals cp damage to nucleus
TAIZ-Zeiger version of ABA signaling 3 groups of receptors 1. GTG in PM 2. CHLH in Cp 3. PYR/PYL/RCAR • cytoplasmic
Schroeder version of ABA signaling 1. PYR/PYL/RCAR is key player • Binds ABA& inactivates PP 2 C
Schroeder version of ABA signaling 1. PYR/PYL/RCAR is key player • Binds ABA& inactivates PP 2 C • Allows Sn. RK 2 to function
Schroeder version of ABA signaling 1. PYR/PYL/RCAR is key player • Binds ABA& inactivates PP 2 C • Allows Sn. RK 2 to function • Sn. RK 2 then kinases many targets, including ion channels, TFs & ROS producers
ABA signaling in Guard Cells
Ethylene A gas that acts as a hormone! Chinese burned incense to ripen pears 1864: leaks from street lamps damage trees
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
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
Ethylene Effects Climacteric fruits produce spike of ethylene at start of ripening & exogenous ethylene enhances this
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
Ethylene Effects Normally IAA from leaf tip keeps abscission zone healthy
Ethylene Effects Normally IAA from leaf tip keeps abscission zone healthy When IAA abscission zone becomes sensitive to ethylene
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
Ethylene Synthesis Made in response to stress, IAA, or during ripening
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
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
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
Ethylene Signaling Receptors were identified by mutants in triple response
Ethylene Signaling Receptors were identified by mutants in triple response Also resemble bacterial 2 -component signaling systems!
Ethylene Signaling Receptors were identified by mutants in triple response Also resemble bacterial 2 -component signaling systems! Receptor is in ER!
Ethylene Signaling 1. In absence of ethylene, receptors activate CTR 1 which represses EIN 2 -dependent signaling
Ethylene Signaling 1. In absence of ethylene, receptors activate CTR 1 which represses EIN 2 -dependent signaling 2. Upon binding ethylene, receptors inactivate CTR 1 by unknown mech
Ethylene Signaling 1. In absence of ethylene, receptors activate CTR 1 which represses EIN 2 -dependent signaling 2. Upon binding ethylene, receptors inactivate CTR 1 by unknown mech 3. Active EIN 2 activates EIN 3
Ethylene Signaling 1. In absence of ethylene, receptors activate CTR 1 which represses EIN 2 -dependent signaling 2. Upon binding ethylene, receptors inactivate CTR 1 by unknown mech 3. Active EIN 2 activates EIN 3 4. EIN 3 turns on genes needed for ethylene response.
Ethylene Signaling 1. In absence of ethylene, receptors activate CTR 1 which represses EIN 2 -dependent signaling 2. Upon binding ethylene, receptors inactivate CTR 1 by unknown mech 3. Active EIN 2 activates EIN 3 4. EIN 3 turns on genes needed for ethylene response. 5. Ethylene receptor also turns off EIN 3 degradation
Jasmonates Fatty acid derivatives first discovered as growth inhibitors made by a fungus
Jasmonates Fatty acid derivatives first discovered as growth inhibitors made by a fungus • Subsequently found to be made by plants in response to stress
Jasmonates Fatty acid derivatives mainly involved in stress signaling • Also needed for pollen development • Maturation • Elongation of stamen filaments • Dehiscence of anther locules
Jasmonates Fatty acid derivatives mainly involved in stress signaling • Also needed for pollen development • JAZ proteins block TF until bind JA
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 • COI 1 = E 3 receptor for JAZ
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 • COI 1 = E 3 receptor for JAZ • JA genes are transcribed • Control pollen development & other cellular effects
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 • COI 1 = E 3 receptor for JAZ • JA genes are transcribed • Control pollen development & other cellular effects, including trichome development
- Slides: 69