The entry of Na+ causes the opening of more voltage- gated Na+ channels and further depolarization, setting up a positive feedback loop .

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#Unit 6. System Physiology – Plant

The ZTL family, has been shown to participate in the control of circadian clocks and flowering.

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#Unit 6. System Physiology – Plant

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#Unit 6. System Physiology – Plant

The photoreceptor for UV-B-induced responses is UVR8, is a seven-bladed b-propeller protein, which forms functionally inactive homodimers in the absence of UV-B

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#Unit 6. System Physiology – Plant

UVR8 lacks a prosthetic chromophore

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#Unit 6. System Physiology – Plant

Upon absorbing UV-B photons, the tryptophans undergo structural changes that break the salt bridges, leading to the dissociation of the two functionally active monomers. The monomers then interact with COP1–SPA complexes to activate gene expression

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#Unit 6. System Physiology – Plant

The UVR8- COP1-SPA complex then activates the transcription of the major transcription factor HY5, which controls the expression of many of the genes induced by UV-B.