1. BLUE LIGHT RESPONSES
Photoropism
Inhibition of stem stem and hypocotyl elongation
Stimulation of chlorophyll and carotenoid synthesis
Stomatal opening
Chloroplast movements
Anthocyanin synthesis

2. ACTION SPECTRUM
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7. Blue light inhibition of elongation
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8. Blue light stimulation of glutamate semialdehyde aminotransferase, an enzyme involved in chlorophyll synthesis
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9. CHLOROPLAST MOVEMENTS -LEMNA
DARK WEAK BLUE LIGHT STRONG BLUE LIGHT
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10. DARK
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11. BLUE LIGHT
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12. CLOSE CORRELATION BETWEEN LIGHT AND STOMATAL OPENING
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21. BLUE LIGHT PHOTORECEPTORS
PHOTOTROPINS : phot1 and phot2
SERVE AS THE BLUE LIGHT PHOTORECEPTORS FOR PHOTOTROPISM, CHLOROPLAST MOVEMEMNTS, AND STOMATAL OPENING
MUTANTS LACK BLUE LIGHT DEPENDENT PHOTOTROPISM, CHLOROPLAST MOVEMENTS, AND STOMATAL OPENING
PHOTOTROPINS ARE FLAVOPROTEINS WITH SER/THR PROTEIN KINASES THAT AUTOPHOSPHORYLATE IN RESPONSE TO BLUE LIGHT

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23. BLUE LIGHT PHOTORECEPTORS (CONT.)
2. CRYPTOCHROMES (cry1 and cry2)
CRYPTOCHROMES PLAY ROLES IN BLUE-LIGHT-MEDIATED GROWTH INHIBITION. MUTANT HYPOCOTYLS ARE NOT INHIBITED BY BLUE LIGHT.
HOWEVER, NO PHOTOCHEMISTRY HAS YET BEEN DEMONSTRATED, AND SO THEY MAY NOT ACT AS PHOTORECEPTORS
CRYPTOCHROMES ALSO FOUND IN ANIMAL CELLS WHERE THEY FUNCTION IN CIRCADIAN RHYTHMS, BUT DO NOT ACT AS PHOTORECEPTORS
CRYPTOCHROMES MAY BE INVOLVED IN SIGNAL TRANSDUCTION DOWNSTREAM OF OTHER BLUE LIGHT PHOTORECEPTORS.

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26. BLUE LIGHT PHOTORECEPTORS (CONT.)
ZEAXANTHIN - CAROTENOID LOCATED IN THE CHLOROPLAST
- MAY REGULATE STOMATAL OPENING. MUTANTS HAVE REDUCED RESPONSE TO BLUE LIGHT.
- ZEAXANTHINS AND PHOTOROPINS MAY WORK TOGETHER IN GUARD CELLS

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29. ZEAXANTHIN CAN UNDERO A CIS-TRANS ISOMERIZATION
BLUE
Trans-Zeaxanthin Cis-Zeaxanthin
GREEN
(THIS MODEL IS STILL HYPOTHETICAL)

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