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Role of Phytochromes in Shade Avoidance Ecophysiological and Molecular aspects PowerPoint PPT Presentation


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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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Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Role ofPhytochromes in Shade AvoidanceEcophysiological and Molecular aspects


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Shade avoidance syndrome


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

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 =


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Photoreceptors in Arabidopsis

Phytochromes A-E


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signal transduction


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome structure and chromophore

-Reception-

chromophore

phytochromobilin

PHY

holoprotein

PHY apoprotein

125 kDa monomer

Native phytochrome occurs as a dimer of 2 equivalent subunits


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome function in Arabidopsis

-Response-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signal transduction


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signal transduction

-emerging themes-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

I. Subcellular partitioning

Phytochrome nucleocytoplasmic trafficking

good correlation between the wavelength requirement for physiological

responses and nuclear import of the different phytochromes


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

I. Subcellular partitioning

Phytochrome nucleocytoplasmic trafficking

phyA

minutes

phyB

hours


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

phyA

II. Proteolytic degradation

Phytochrome


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

The ubiquitin/26S proteasome pathway

major proteolytic pathway in plants and animals


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

The ubiquitin/26S proteasome pathway


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Light signal transduction

-mutant analysis: light vs dark-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Long Hypocotyl 5 - HY5

long hypocotyl in R, FR and B


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signal transduction

-cop/det/fus mutants-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

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-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

F

Phytochrome signal transduction

- cop/det/fus mutants -


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

COP1 - HY5 interaction


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochromes (PHY)

–responses to red and far-red light-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

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)


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signal transduction

-identified mutants-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signal transduction

-proteolytic degradation-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signal transduction

-phytochrome interacting factors-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Yeast two-hybrid analysis


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Isolation of Phytochrome Interacting Factor3

-a basic helix-loop-helixtranscription factor protein-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

PIF3 negatively regulates phyB- but not phyA-

mediated inhibition of hypocotyl elongation


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signal transduction

-bHLH class PIF3-like transcription factors-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

III. Phosphorylation

-Phytochromes are similar to histidine kinases-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Two component signaling

-intermezzo-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

III. Phosphorylation

-Phytochrome Ser/Thr-kinase activity-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

III. Phosphorylation

-phytochrome phosphorylation status; PAPP5-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

III. Phosphorylation

-Phytochrome Ser/Thr-kinase activity; external targets-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signal transduction

-phosphorylation of phytochrome interacting factors-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

IV. Regulation of transcription

phytochrome responses are associated with massive alterationsin gene expression


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

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


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

IV. Regulation of transcription

-light/phytochrome responsive promoters-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Light regulated transcription factors

-transcription-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Light regulated transcription factors

-post-transcriptional regulation; phosphorylation-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Light regulated transcription factors

post-transcriptional regulation;

phosphorylation, cellular localization


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Light regulated transcription factors

-post-transcriptional regulation; degradation-


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

PIF3 as an example

cellular trafficking, gene expression, phosphorylation, degradation


Role of phytochromes in shade avoidance ecophysiological and molecular aspects

Phytochrome signaling

Further downstream targets; phytohormones


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