Plant Photoreceptors Lecture Notes PDF
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These notes provide an overview of plant photoreceptors, including their roles in responding to light, and the molecular mechanisms involved. The notes cover topics like phytochromes, cryptochromes, phototropins, and UV responses, with illustrations and figures.
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Signals From Sunlight TMMZ Fig 16.1 Required Reading - TMMZ Chapter 16, all sections 3 Light wavelength and intensity are important Ultraviolet (UV) 290 TMMZ Fig. 9.2 4 Light wavelength and intensity are important TMMZ Table 16.1 5 Light wavelength and intensity are important TMMZ Fig...
Signals From Sunlight TMMZ Fig 16.1 Required Reading - TMMZ Chapter 16, all sections 3 Light wavelength and intensity are important Ultraviolet (UV) 290 TMMZ Fig. 9.2 4 Light wavelength and intensity are important TMMZ Table 16.1 5 Light wavelength and intensity are important TMMZ Fig 16.2 https://www.thoughtco.com/phototropism-419215 Photoreceptors – action spectra Bilodeau et al., 2019 Front. Plant Sci 29 6 Plant Photoreceptors See also TMMZ Fig. 16.8 Chromophore 7 8 Phytochrome Pr red light Pfr far red light • • • • Primary receptor for R and FR light Photoreversible molecule (not 100%) Thermal reversion to Pr in the dark Pfr is the active form 9 Pfr is the active form of phytochrome Pr Pfr nucleus TMMZ Fig 16.10 Phytochrome Responses 10 • Two general categories: rapid biochemical events slower morphological changes • Vary in lag and escape time: lag- minutes to weeks! escape from photoreversibility – seconds to hours Phytochrome Responses 11 TMMZ Fig, 16.12 12 Two examples of phytochrome responses Germination of some plant species (e.g., lettuce) TMMZ Fig. 16.5 Plants wait for the lights to turn red Devlin 2016 PNAS 113:7301-7303 13 14 Blue-light responses • Delay (seconds to minutes) between receiving blue light signal and seeing maximum response • Response continues after the blue light has been switched off 15 Cryptochromes • FAD chromophore absorbs blue light • Change in FAD redox state to FADH • Photoreceptor changes shape and is activated TMMZ Fig. 16.16B Cryptochrome Responses 16 17 Phototropins Chloroplast synthesis & movement Maai et al. (2019) Plant Prod. Sci. Phototropism https://www.thoughtco.com/phototropism-419215 18 Responses to Ultraviolet (UV) Radiation Gene regulation UV-B tolerance Flavonoid biosynthesis Hypocotyl growth suppression Leaf/epidermal cell expansion Endoreduplication in epidermal cells Stomatal density Entrainment of circadian clock Increased photosynthetic efficiency TMMZ Table 16.4 19 UVR8 TMMZ Fig. 16.27
