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First published online September 29, 2006; 10.1105/tpc.105.037358 The Plant Cell 18:2506-2516 (2006) © 2006 American Society of Plant Biologists Arabidopsis FHY3 Specifically Gates Phytochrome Signaling to the Circadian Clock[W]
a Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom 2 To whom correspondence should be addressed. E-mail paul.devlin{at}rhul.ac.uk; fax 44-1784-434326.
Circadian gating of light signaling limits the timing of maximum responsiveness to light to specific times of day. The fhy3 (for far-red elongated hypocotyl3) mutant of Arabidopsis thaliana is involved in independently gating signaling from a group of photoreceptors to an individual response. fhy3 shows an enhanced response to red light during seedling deetiolation. Analysis of two independent fhy3 alleles links enhanced inhibition of hypocotyl elongation in response to red light with an arrhythmic pattern of hypocotyl elongation. Both alleles also show disrupted rhythmicity of central-clock and clock-output gene expression in constant red light. fhy3 exhibits aberrant phase advances under red light pulses during the subjective day. Release-from-light experiments demonstrate clock disruption in fhy3 during the early part of the subjective day in constant red light, suggesting that FHY3 is important in gating red light signaling for clock resetting. The FHY3 gating function appears crucial in the early part of the day for the maintenance of rhythmicity under these conditions. However, unlike previously described Arabidopsis gating mutants that gate all light signaling, gating of direct red lightinduced gene expression in fhy3 is unaffected. FHY3 appears to be a novel gating factor, specifically in gating red light signaling to the clock during daytime. This article has been cited by other articles:
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