title: Dual role of TOC1 in the control of circadian and photomorphogenic responses in Arabidopsis.
abstract: 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.
authors.affiliation: Department of Cell Biology, Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: Paloma
authors.initials: P
authors.lastname: Más
authors.forename: David
authors.initials: D
authors.lastname: Alabadí
authors.forename: Marcelo J
authors.initials: MJ
authors.lastname: Yanovsky
authors.forename: Tokitaka
authors.initials: T
authors.lastname: Oyama
authors.forename: Steve A
authors.initials: SA
authors.lastname: Kay
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics; D003624:Darkness; D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D018546:Hypocotyl / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D009154:Mutation; D010834:Phytochrome / Q000378:metabolism; D030821:Plants, Genetically Modified; D034622:RNA Interference / Q000502:physiology; D015398:Signal Transduction / Q000528:radiation effects; D014157:Transcription Factors / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D004268:DNA-Binding Proteins; C113192:LHY protein, Arabidopsis; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors; D010834:Phytochrome