Environmental Regulations of Plants

Environmental Regulations of Plants - Environmental...

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Environmental Regulation of Plants v Plants are responsive to environment v Many hormone transduction pathways link environment to plant response Ø Light Ø Gravity Ø Pathogen
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ETIOLATION Plants have cellular receptors to detect important changes in environment Ø Potato growing in darkness: long, spindly stems, unopened leaves and little root development Ø response to NO LIGHT (no need for photosynthesis) Ø shoot growth for emergence through the soil
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DE-ETIOLATION After potato is exposed to light Ø The plant undergoes profound changes called de- etiolation Ø Short stems, expanded leaves, chlorophyll production and extensive root development Ø Emergence from soil means sunlight for photosynthesis and extensive changes must occur to support photosynthesis
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Molecular Bases for De-etiolation "Greening" in response to light 1 The light signal is detected by the phytochrome receptor, which then activates at least two signal transduction pathways. 2 One pathway uses cGMP as a second messenger that activates a specific protein kinase.The other pathway involves an increase in cytoplasmic Ca2+ that activates another specific protein kinase. 3 Both pathways lead to expression of genes for proteins that function in the de-etiolation (greening) response.
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v Responses to light are critical for plant success v Light cues many key events in plant growth and development v Effects of light on plant morphology: Are what plant biologists call photomorphogenesis v Plants detect more than light presence: direction, intensity and wavelength (color) PHOTOMORPHOGENESIS
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Action Spectrum n of light causing specific photomorphogenesis Action spectrum for maize phototropism Absorption Spectrum: — of light absorbed by receptor Action spectrum for phototropism corresponds to blue-light absorption spectrum
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of Photoreceptors Ø Matching action and absorption spectra
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Environmental Regulations of Plants - Environmental...

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