Control of Circadian Rhythms and Photoperiodic Flowering by the Arabidopsis GIGANTEA Gene

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Science  03 Sep 1999:
Vol. 285, Issue 5433, pp. 1579-1582
DOI: 10.1126/science.285.5433.1579

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Photoperiodic responses in plants include flowering that is day-length–dependent. Mutations in the Arabidopsis thaliana GIGANTEA (GI) gene cause photoperiod-insensitive flowering and alteration of circadian rhythms. The GI gene encodes a protein containing six putative transmembrane domains. Circadian expression patterns of the GI gene and the clock-associated genes, LHY and CCA1, are altered in gi mutants, showing that GI is required for maintaining circadian amplitude and appropriate period length of these genes. Thegi-1 mutation also affects light signaling to the clock, which suggests that GI participates in a feedback loop of the plant circadian system.

  • * These authors contributed equally to this work.

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

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