Dual Role of TOC1 in the Control of Circadian and Photomorphogenic Responses in Arabidopsis[W]

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  • Paloma Más
    Department of Cell Biology and Institute for Childhood and Neglected Diseases, Scripps Research Institute, La Jolla, California 92037
  • David Alabadí
    Department of Cell Biology and Institute for Childhood and Neglected Diseases, Scripps Research Institute, La Jolla, California 92037
  • Marcelo J. Yanovsky
    Department of Cell Biology and Institute for Childhood and Neglected Diseases, Scripps Research Institute, La Jolla, California 92037
  • Tokitaka Oyama
    Department of Cell Biology and Institute for Childhood and Neglected Diseases, Scripps Research Institute, La Jolla, California 92037
  • Steve A. Kay
    Department of Cell Biology and Institute for Childhood and Neglected Diseases, Scripps Research Institute, La Jolla, California 92037

Description

<jats:title>Abstract</jats:title><jats:p>To examine the role of the TOC1 (TIMING OF CAB EXPRESSION1) gene in the Arabidopsis circadian system, we generated a series of transgenic plants expressing a gradation in TOC1 levels. Silencing of the TOC1 gene causes arrhythmia in constant darkness and in various intensities of red light, whereas in blue light, the clock runs faster in silenced plants than in wild-type plants. Increments in TOC1 gene dosage delayed the pace of the clock, whereas TOC1 overexpression abolished rhythmicity in all light conditions tested. Our results show that TOC1 RNA interference and toc1-2 mutant plants displayed an important reduction in sensitivity to red and far-red light in the control of hypocotyl elongation, whereas increments in TOC1 gene dosage clearly enhanced light sensitivity. Furthermore, the red light–mediated induction of CCA1/LHY expression was decreased in TOC1 RNA interference and toc1-2 mutant plants, indicating a role for TOC1 in the phytochrome regulation of circadian gene expression. We conclude that TOC1 is an important component of the circadian clock in Arabidopsis with a crucial function in the integration of light signals to control circadian and morphogenic responses.</jats:p>

Journal

  • The Plant Cell

    The Plant Cell 15 (1), 223-236, 2003-01-01

    Oxford University Press (OUP)

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