Photomorphogenesis Skotomorphogenesis(etiolation)
Light has an influence on seedling development
Photomorphogenesis
inhibition of hypocotyl elongation
opening of apical hook
cotyledon expansion
chloroplast development
Dark Light
Dark
Light
wild-type
cop/detmutants
COP and DET proteins inhibit photomorphogenesis
Development (realization of a phenotype from a genotype)
is controlled by
endogenous factors
intercellular regulation
phytohormones
exogenous factors
biotic factors
abiotic factors
Germination of lettuce seeds (photoreversibility)
Reversible R/FR response system controlled by phytochrome
germination germination
Pr PfrRed light
Far-red light
inactive active
Phytochrome dogma
synthesisgermination,flower Induction……
red light
far red light
Phytochrome: from synthesis to action
blue light red light
Arabidopsis: 5 phytochrome proteins (phyA - phy E),
differ in their apoproteins
Phytochrome: homodimeric chromoprotein:
apoprotein and phytochromobilin (open chained tetrapyrrol) as chromophor form holoprotein
Strasburger, 2002
R FR
PRinactive
PFRactive
PFR
active
PR
inactive
sensor signal transduction
Regulatory function
Strasburger, 2002
Structure of phytochrome proteins
N-terminal extension
Hinge region
PAS domain
Histidine kinase related 1
Histidine kinase related 2
Chromophore binding domain
The Phytochrome apoprotein (-chromophore) is a 125kD monomer
Chromophore binding domains
Two holoproteins (+chromophore) form a dimer
IIAIA
IIBIB
Red light
Far-red light
PrPfr
Two holoproteins (+chromophore) form a dimer
Histidine kinase related
Chromophore binding domain
IIAIA
IIBIB
IA IIA
IIBIB
Phytochrome responses vary with amount of light
VLFR: 0.00001 µmol x m-2
LFR: 1-1000 µmol x m-2
Arabidopsis seed germination
Lettuce seed germination
Anthocyanin synthesisInhibition of hypocotyl elong.Enlargement of cotyledonsApical hook opening
HIR: >1000 µmol x m-2 x s-1
Phytochrome responses vary with amount of light
Inhibition of hypocotyl elongation
HIR: >1000 µmol x m-2 x s-1
Phytochrome responses vary with amount of light
LFR: 1-1000 µmol x m-2
Lettuce seed germination
Strasburger, 2002
Shade avoidance reaction
Strasburger, 2002
Shade avoidance reaction
Strasburger, 2002
Shade avoidance reaction
Figure 17.9 Phytochrome is an autophosphorylating protein
kinase
PHYA-GFP and PHYB-GFP fusion proteins migrate into the nucleus
PHYA-GFP
PHYB-GFP
Dark Red
Dark Red