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First published online May 11, 2007; 10.1105/tpc.106.047241 The Plant Cell 19:1522-1536 (2007) © 2007 American Society of Plant Biologists TIME FOR COFFEE Encodes a Nuclear Regulator in the Arabidopsis thaliana Circadian Clock[W]
a Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne D-50829, Germany 1 To whom correspondence should be addressed. E-mail davis{at}mpiz-koeln.mpg.de; fax 49-221-5062-207.
The plant circadian clock is required for daily anticipation of the diurnal environment. Mutation in Arabidopsis thaliana TIME FOR COFFEE (TIC) affects free-running circadian rhythms. To investigate how TIC functions within the circadian system, we introduced markers for the evening and morning phases of the clock into tic and measured evident rhythms. The phases of evening clock genes in tic were all advanced under light/dark cycles without major expression level defects. With regard to morning-acting genes, we unexpectedly found that TIC has a closer relationship with LATE ELONGATED HYPOCOTYL (LHY) than with CIRCADIAN CLOCK ASSOCIATED1, as tic has a specific LHY expression level defect. Epistasis analysis demonstrated that there were no clear rhythms in double mutants of tic and evening-acting clock genes, although double mutants of tic and morning-acting genes exhibited a similar free-running period as tic. We isolated TIC and found that its mRNA expression is continuously present over the diurnal cycle, and the encoded protein appears to be strictly localized to the nucleus. Neither its abundance nor its cellular distribution was found to be clock regulated. We suggest that TIC encodes a nucleus-acting clock regulator working close to the central oscillator. This article has been cited by other articles:
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