Cloning of the Arabidopsis Clock Gene TOC1, an Autoregulatory Response Regulator Homolog

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Science  04 Aug 2000:
Vol. 289, Issue 5480, pp. 768-771
DOI: 10.1126/science.289.5480.768

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The toc1 mutation causes shortened circadian rhythms in light-grown Arabidopsis plants. Here, we report the same toc1 effect in the absence of light input to the clock. We also show that TOC1 controls photoperiodic flowering response through clock function. The TOC1 gene was isolated and found to encode a nuclear protein containing an atypical response regulator receiver domain and two motifs that suggest a role in transcriptional regulation: a basic motif conserved within theCONSTANS family of transcription factors and an acidic domain. TOC1 is itself circadianly regulated and participates in a feedback loop to control its own expression.

  • * Present address: Department of Plant Biology, Ohio State University, Columbus, OH 43210, USA.

  • Present address: Novartis Agricultural Discovery Institute, San Diego, CA 92121, USA.

  • To whom correspondence should be addressed. E-mail: stevek{at}

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