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Role of Phytochromes in Shade Avoidance Ecophysiological and Molecular aspects

Role of Phytochromes in Shade Avoidance Ecophysiological and Molecular aspects. Shade avoidance syndrome. Plants adapt to changes in light conditions -Shade Avoidance Syndrome-. photon fluence rate in 10 nm band centered on 660 nm photon fluence rate in 10 nm band centered on 730 nm.

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Role of Phytochromes in Shade Avoidance Ecophysiological and Molecular aspects

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  1. Role ofPhytochromes in Shade AvoidanceEcophysiological and Molecular aspects

  2. Shade avoidance syndrome

  3. Plants adapt to changes in light conditions -Shade Avoidance Syndrome- photon fluence rate in 10 nm band centered on 660 nm photon fluence rate in 10 nm band centered on 730 nm R/FR =

  4. Photoreceptors in Arabidopsis Phytochromes A-E

  5. Phytochrome signal transduction

  6. Phytochrome structure and chromophore -Reception- chromophore phytochromobilin PHY holoprotein PHY apoprotein 125 kDa monomer Native phytochrome occurs as a dimer of 2 equivalent subunits

  7. Phytochrome function in Arabidopsis -Response-

  8. Phytochrome signal transduction

  9. Phytochrome signal transduction -emerging themes-

  10. I. Subcellular partitioning Phytochrome nucleocytoplasmic trafficking good correlation between the wavelength requirement for physiological responses and nuclear import of the different phytochromes

  11. I. Subcellular partitioning Phytochrome nucleocytoplasmic trafficking phyA minutes phyB hours

  12. phyA II. Proteolytic degradation Phytochrome

  13. The ubiquitin/26S proteasome pathway major proteolytic pathway in plants and animals

  14. The ubiquitin/26S proteasome pathway

  15. Light signal transduction -mutant analysis: light vs dark-

  16. Long Hypocotyl 5 - HY5 long hypocotyl in R, FR and B

  17. Phytochrome signal transduction -cop/det/fus mutants-

  18. COP/DET/FUS name Other protein name Function Putative ubiquitin ligase component COP1 DET1 COP10 COP16 COP11 FUS12 FUS11 COP8 FUS5 COP9 Protein required for HY5 degrad. E2 Ub-conjugating enzymevariant Not cloned CSN1 CSN2 CSN3 CSN4 CSN7 CSN8 COP9 signalosome subunit COP9 signalosome subunit COP9 signalosome subunit COP9 signalosome subunit COP9 signalosome subunit COP9 signalosome subunit Phytochrome signal transduction -cop/det/fus mutants-

  19. F Phytochrome signal transduction - cop/det/fus mutants -

  20. COP1 - HY5 interaction

  21. Phytochromes (PHY) –responses to red and far-red light-

  22. Phytochrome signal transduction -more sophisticated screens: light quality- Mutants that exhibit light-grown characteristics in the dark Mutants that exhibit altered seedling development under specific light conditions Wt phyA phyAspa1 Wt rsf1 e.g. Far-red light (phyA)

  23. Phytochrome signal transduction -identified mutants-

  24. Phytochrome signal transduction -proteolytic degradation-

  25. Phytochrome signal transduction -phytochrome interacting factors-

  26. Yeast two-hybrid analysis

  27. Isolation of Phytochrome Interacting Factor3 -a basic helix-loop-helixtranscription factor protein-

  28. PIF3 negatively regulates phyB- but not phyA- mediated inhibition of hypocotyl elongation

  29. Phytochrome signal transduction -bHLH class PIF3-like transcription factors-

  30. III. Phosphorylation -Phytochromes are similar to histidine kinases-

  31. Two component signaling -intermezzo-

  32. III. Phosphorylation -Phytochrome Ser/Thr-kinase activity-

  33. III. Phosphorylation -phytochrome phosphorylation status; PAPP5-

  34. III. Phosphorylation -Phytochrome Ser/Thr-kinase activity; external targets-

  35. Phytochrome signal transduction -phosphorylation of phytochrome interacting factors-

  36. IV. Regulation of transcription phytochrome responses are associated with massive alterationsin gene expression

  37. IV. Regulation of transcription -Immediate phytochrome targets- 44% (far-red light) and 25% (red light) of early light-responsive genes (< 1 hr) encode transcription factors

  38. IV. Regulation of transcription -light/phytochrome responsive promoters-

  39. Light regulated transcription factors -transcription-

  40. Light regulated transcription factors -post-transcriptional regulation; phosphorylation-

  41. Light regulated transcription factors post-transcriptional regulation; phosphorylation, cellular localization

  42. Light regulated transcription factors -post-transcriptional regulation; degradation-

  43. PIF3 as an example cellular trafficking, gene expression, phosphorylation, degradation

  44. Phytochrome signaling Further downstream targets; phytohormones

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