EnvReg213-page7 - The red-sensitive photoreceptors are a...

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Plant Environmental Regulators - 7 Action spectra studies of plant responses to light indicate plants have photoreceptors sensitive to red and to blue light. Blue-light activated phototropism Shoot Phototropism There are at least three blue light absorbing pigment photoreceptors, cryptochromes, phototropin, and zeaxanthin that function in different reactions. All three photoreceptors activate signal transduction pathways that induce auxin migration. Cryptochromes, found in hypocotyl cells, inhibit hypocotyl elongation. Phototropin is involved in most phototropic (differential growth) responses. Zeaxanthin functions in stomatal opening. Blue light receptor conformational change and auto-phosphorylation of kinase domain
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Unformatted text preview: The red-sensitive photoreceptors are a group of pigments called phytochromes. Phytochrome was discovered in lettuce, a plant whose seeds only germinate when exposed to light. A USDA team in the 1930's exposed lettuce seeds to red light of 660 nm. (It was known that cocklebur flowered best when stimulated with red light of 669 nm and they thought the germination response might be similar.) 660 nm promoted the best germination in lettuce. However, if the 660nm exposure was followed by a flash of far-red light at 730 nm, seeds did not germinate....
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This note was uploaded on 01/08/2012 for the course BIO 213 taught by Professor Makina during the Fall '09 term at SUNY Stony Brook.

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