The Arabidopsis sickle Mutant Exhibits Altered Circadian Clock Responses to Cool Temperatures and Temperature-Dependent Alternative Splicing.
The circadian clock allows plants to anticipate and respond to daily changes in ambient temperature. Mechanisms establishing the timing of circadian rhythms in Arabidopsis thaliana through temperature entrainment remain unclear. Also incompletely understood is the temperature compensation mechanism that maintains consistent period length within a range of ambient temperatures. A genetic screen for Arabidopsis mutants affecting temperature regulation of the PSEUDO-RESPONSE REGULATOR7 promoter yielded a novel allele of the SICKLE (SIC) gene. This mutant, sic-3, and the existing sic-1 mutant both exhibit low-amplitude or arrhythmic expression of core circadian clock genes under cool ambient temperature cycles, but not under light-dark entrainment. sic mutants also lengthen free running period in a manner consistent with impaired temperature compensation. sic mutant alleles accumulate LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED1 (CCA1) splice variants, among other alternatively spliced transcripts, which is exacerbated by cool temperatures. The cca1-1 lhy-20 double mutant is epistatic to sic-3, indicating the LHY and CCA1 splice variants are needed for sic-3 circadian clock phenotypes. It is not expected that SIC is directly involved in the circadian clock mechanism; instead, SIC likely contributes to pre-mRNA metabolism, and the splice variants that accumulate in sic mutants likely affect the circadian clock response to cool ambient temperature.
Plant Gene Expression Center, U.S. Department of Agriculture-Agricultural Research Service, Albany, California 94710.|Department of Plant and Microbial Biology, University of California, Berkeley, California 94720.
Carine M
0000-0001-7178-4664
CM
Marshall
Plant Gene Expression Center, U.S. Department of Agriculture-Agricultural Research Service, Albany, California 94710.|Department of Plant and Microbial Biology, University of California, Berkeley, California 94720.
Virginia
V
Tartaglio
Plant Gene Expression Center, U.S. Department of Agriculture-Agricultural Research Service, Albany, California 94710.|Department of Plant and Microbial Biology, University of California, Berkeley, California 94720.
Maritza
0000-0002-5741-6483
M
Duarte
Plant Gene Expression Center, U.S. Department of Agriculture-Agricultural Research Service, Albany, California 94710 fharmon@berkeley.edu.|Department of Plant and Microbial Biology, University of California, Berkeley, California 94720.
Frank G
0000-0001-7017-5373
FG
Harmon
D017398:Alternative Splicing / Q000235:genetics / Q000502:physiology; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D057906:Circadian Clocks / Q000235:genetics / Q000502:physiology; D003080:Cold Temperature; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D004268:DNA-Binding Proteins; C113192:LHY protein, Arabidopsis; D014157:Transcription Factors