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- Title
Self-Regulatory Circuit of CIRCADIAN CLOCK-ASSOCIATED1 Underlies the Circadian Clock Regulation of Temperature Responses in Arabidopsis.
- Authors
Seo, Pil Joon; Park, Mi-Jeong; Lim, Mi-Hye; Kim, Sang-Gyu; Lee, Minyoung; Baldwin, Ian T.; Park, Chung-Mo
- Abstract
The circadian clock synchronizes biological processes to daily cycles of light and temperature. Clock components, including CIRCADIAN CLOCK-ASSOCIATED1 (CCA1), are also associated with cold acclimation. However, it is unknown how CCA1 activity is modulated in coordinating circadian rhythms and cold acclimation. Here, we report that self-regulation of Arabidopsis thaliana CCA1 activity by a splice variant, CCA1β, links the clock to cold acclimation. CCA1β interferes with the formation of CCA1α-CCA1α and LATE ELONGATED HYPOCOTYL (LHY)-LHY homodimers, as well as CCA1α-LHY heterodimers, by forming nonfunctional heterodimers with reduced DNA binding affinity. Accordingly, the periods of circadian rhythms were shortened in CCA1β -overexpressing transgenic plants (35S: CCA1β), as observed in the cca1 lhy double mutant. In addition, the elongated hypocotyl and leaf petiole phenotypes of CCA1α -overexpressing transgenic plants (35S: CCA1α) were repressed by CCA1β coexpression. Notably, low temperatures suppressed CCA1 alternative splicing and thus reduced CCA1β production. Consequently, whereas the 35S: CCA1α transgenic plants exhibited enhanced freezing tolerance, the 35S: CCA1β transgenic plants were sensitive to freezing, indicating that cold regulation of CCA1 alternative splicing contributes to freezing tolerance. On the basis of these findings, we propose that dynamic self-regulation of CCA1 underlies the clock regulation of temperature responses in Arabidopsis.
- Subjects
TEMPERATURE control; ALTERNATIVE RNA splicing; TRANSGENIC plants; BIOLOGICAL rhythms; CIRCADIAN rhythms; HETERODIMERS; ARABIDOPSIS
- Publication
Plant Cell, 2012, Vol 24, Issue 6, p2427
- ISSN
1040-4651
- Publication type
Article
- DOI
10.1105/tpc.112.098723