Lesson 5 (2-3-16) - Lesson 5 Plant Environment Interactions Signaling Plant Sensory Systems Photomorphogenesis Phytochrome Pfr and expression of

Lesson 5 (2-3-16) - Lesson 5 Plant Environment Interactions...

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Lesson 5: Plant Environment Interactions; Signaling Plant Sensory Systems Photomorphogenesis Phytochrome P fr and expression of light-response genes o P r o P fr Regulates gene expression Expression of cytokines (cell signals) Based on quality of light o Proteasome Plants can tell the difference between the shade of a rock or tree trunk and the shade of leaves o Leaves of other (competing) plants absorb red light and leave behind more far red light which simulates the phytochrome system so the plant “avoids shade” and grows toward light (photomorphogenesis) Activation of light response genes o Kinase Domain of P fr Growth responses and phytochrome o Seed germination o Shoot elongation Etiolation o Plant crowding Other light effects o Phototropism Directional growth Growth toward a certain type of light o Blue wavelength – chlorophyll like blue light Phototropins 1 & 2 o Circadian clocks Entrained by light (plants can adapt to seasons) o Signal transduction = a signal binds to receptor and there is an internal cellular response Responses to gravity o Gravitropism Align with gravitational field Stems bend away from a center of gravity Roots bend toward center of gravity
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More auxin at bottom of stem increases cell stretching and some growth Amyloplasts accumulate auxin Starchy bodies in plants Responses to mechanical stimuli o Thigmomorphogenesis o Thigmotropism
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  • Spring '08
  • GEORGESIMMONS
  • Biology

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