Growth regulators Auxins Cytokinins Gibberellins Abscisic Acid Ethylene Brassinoteroids

1. Growth regulators Auxins Cytokinins Gibberellins Abscisic Acid Ethylene Brassinoteroids Jasmonic Acid Salicylic Acid Strigolactones Nitric Oxide Sugars

2. 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)!

3. 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

4. Gibberellins & barley germination GAs made by embryo diffuse to aleurone & trigger events leading to germination

5. GA & stem elongation GA increase elongation, but lag >>> IAA

6. GA & stem elongation GA increase elongation, but lag >>> IAA Increase cell wall creepage, but don't change pH (much)

7. 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

8. 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

9. 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

10. Incredible diversity of functions! • Epigenetic • Directly regulating transcription • Post-transcriptional regulation • Some are made by Pol II, others by Pol III

11. ncRNA mutants • Extracted total RNA from a mix of tissues, separated by size and sequenced 50-300 nt fraction

12. ncRNA mutants • Extracted total RNA from a mix of tissues, separated by size and sequenced 50-300 nt fraction • BLAST to find relatives (and discard tRNA, etc)

13. ncRNA mutants • Extracted total RNA from a mix of tissues, separated by size and sequenced 50-300 nt fraction • BLAST to find relatives (and discard tRNA, etc) • T-DNA express to find mutants

14. ncRNA mutants • Extracted total RNA from a mix of tissues, separated by size and sequenced 50-300 nt fraction • BLAST to find relatives (and discard tRNA, etc) • T-DNA express to find mutants • ordered seeds for ones we found interesting

15. ncRNA mutants • Extracted total RNA from a mix of tissues, separated by size and sequenced 50-300 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

16. ncRNA mutants Grew them and looked for ones that looked funny

17. ncRNA mutants • Grew them and looked for ones that looked funny

18. ncRNA mutants • Grew them and looked for ones that looked funny • Expression of flanking genes is not affected

19. 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.

20. GA & other hormones GA interacts w many other hormones t/o plant life cycle

21. GA & other hormones GA interacts w many other hormones t/o plant life cycle + with auxin via DELLA & induction of GA synthesis

22. 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

23. 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

24. 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

25. ABA • Counteracts GA effects • Causes seed dormancy & • inhibits seed germination • Inhibits fruit ripening

26. ABA Also made in response to many stresses. Most is made in root & transported to shoot

27. ABA Most is made in root & transported to shoot in response to stress Closes stomates by opening Ca then closing K channels

28. 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)

29. 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

30. 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

31. Jae-Hoon Lee • Found T-DNA insertions in DWD • 3 were sensitive to ABA

32. Jae-Hoon Lee • Found T-DNA insertions in DWD proteins • 3 were sensitive to ABA • ABI5 was elevated in dwa mutants

33. 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

34. TAIZ-Zeiger version of ABA signaling • 3 groups of receptors • GTG in PM • Resemble GPCR

35. 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

36. TAIZ-Zeiger version of ABA signaling • 3 groups of receptors • GTG in PM • CHLH in Cp • Also catalyzes Chl synthesis

37. 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

38. TAIZ-Zeiger version of ABA signaling • 3 groups of receptors • GTG in PM • CHLH in Cp • PYR/PYL/RCAR • cytoplasmic

39. Schroeder version of ABA signaling • PYR/PYL/RCAR is key player • Binds ABA& inactivates PP2C

40. Schroeder version of ABA signaling • PYR/PYL/RCAR is key player • Binds ABA& inactivates PP2C • Allows SnRK2 to function

41. 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

42. ABA signaling in Guard Cells

43. Ethylene A gas that acts as a hormone! Chinese burned incense to ripen pears 1864: leaks from street lamps damage trees

44. 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

45. 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

46. Ethylene Effects Climacteric fruits produce spike of ethylene at start of ripening & exogenous ethylene enhances this

47. 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

48. Ethylene Effects Normally IAA from leaf tip keeps abscission zone healthy

49. Ethylene Effects Normally IAA from leaf tip keeps abscission zone healthy When IAA abscission zone becomes sensitive to ethylene

50. 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