life on earth depends on light derived from the sun
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Life on earth depends on light derived from the sun
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Photosynthesis
Light is required to help water reduce NADP+
PS2680nm
PS1700 nm
ATP
NADPH
Light energizes jumps in energy potentialto get electrons run through anelectron transfer chain
H2O 2H+ + 1/2O2
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Engelmann experiment
What is an action
spectrum??
And what is an absorption spectrum??
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Action spectrum vs. absorption spectrum
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Directionality of blue light induced bending
(Action spectrum)
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Directionality of blue light induced bending
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Kinetics of blue light effects
Membrane depolarization
Hypocotylelongation
Hypocotylelongation
Gene induction
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Stomata opening regulated by blue light
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Stomata opening regulated by blue light
Protoplasts
dark
Protoplasts
blue light
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Measuring irradiation:
chloroplast movements (Lemna) depending
on light intensity
Dunkelheit Schwachlicht Starklicht
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Blue light induced bending of coleoptiles
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phot1 (phototropin1)
blue light
wild-type
phot1 mutant
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PHOT genes in Arabidopsis
LOV-domains are flavin binding sites (FMN)
LOV-domains change redox status in proteins through (Light, Oxygen, Voltage)
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Phototropism chloroplast stomata movement opening
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cryptochrome, together with phytochromes
deetiolation of seedlings
photoperiodic induced morphoses (e.g. flower induction)
circadian rhythms
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dark blue red
WT cry1 phyB WT cry1 phyB WT cry1 phyB
cry1 : inhibition of hypocotyl elongation is insensitiv against blue light
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dark blue
WT cry1 phyB WT cry1 phyB
cry1 : analysis of cry1 mutants and over-producers
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MTHF (pterin)
8-HDF (deazaflavin)
FADH-
CRY1 shows similarity to prokaryotic DNA photolyases
CRY1
bacterialphotolyase
70% 70%30%
Chromophor 1: Chromophor 2:
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SKOTOMORPHOGENESIS
Photomorphogenesis Skotomorphogenesis
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SKOTOMORPHOGENESIS
Skotomorphogenesis
Light has an influence on seedling development
Photomorphogenesis Skotomorphogenesis
Hypocotyl: long short
Apical hook: closed open
Cotyledons: closed expanded
Chloroplasts: proplastids fully developed
Photosynthesis: no yes
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Cotyledon expansion
Reduced hypocotylelongation
Open apical hook
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closed apical hook Non-expanded
cotyledons
Etiolated hypocotyl
Is skotomorphogenesis achived via active repression of photomorphogenesis
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How to perform genetic approaches todecifer light regulation in plants ???
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How to perform genetic approaches todecifer light regulation in plants ???
Photomorphogenesisin dark grown seedlings
Skotomorphogenesis in light grown seedlings
Asking simple questions
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Getting complicated answers !!
Shorthypocotyl
Expanded cotyledons
Open apical hook
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Skotomorphogenesis in the light
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Functions of cop/det gene products
COP1 phytochrome chromophore biosynthesis
DET1 phytochrome B
COP9 phytochrome A
DET2 brassinosteroid biosynthesis
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Dark
Light
wild-type
cop/detmutants
COP and DET proteins inhibit photomorphogenesis
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Strasburger, 2002
Shade avoidance reaction