title: HsfB2b-mediated repression of PRR7 directs abiotic stress responses of the circadian clock.
abstract: The circadian clock perceives environmental signals to reset to local time, but the underlying molecular mechanisms are not well understood. Here we present data revealing that a member of the heat shock factor (Hsf) family is involved in the input pathway to the plant circadian clock. Using the yeast one-hybrid approach, we isolated several Hsfs, including Heat Shock Factor B2b (HsfB2b), a transcriptional repressor that binds the promoter of Pseudo Response Regulator 7 (PRR7) at a conserved binding site. The constitutive expression of HsfB2b leads to severely reduced levels of the PRR7 transcript and late flowering and elongated hypocotyls. HsfB2b function is important during heat and salt stress because HsfB2b overexpression sustains circadian rhythms, and the hsfB2b mutant has a short circadian period under these conditions. HsfB2b is also involved in the regulation of hypocotyl growth under warm, short days. Our findings highlight the role of the circadian clock as an integrator of ambient abiotic stress signals important for the growth and fitness of plants.
authors.affiliation: Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089; and.
authors.forename: Elsebeth
authors.initials: E
authors.lastname: Kolmos
authors.affiliation: Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089; and.
authors.forename: Brenda Y
authors.initials: BY
authors.lastname: Chow
authors.affiliation: Cell and Developmental Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Pruneda-Paz
authors.affiliation: Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089; and stevekay@usc.edu.
authors.forename: Steve A
authors.initials: SA
authors.lastname: Kay
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D057906:Circadian Clocks / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018546:Hypocotyl / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C570277:HsfB2b protein, Arabidopsis; C523308:PRR7 protein, Arabidopsis; D010940:Plant Proteins; D012097:Repressor Proteins; D014157:Transcription Factors
keywords: Hsf; circadian clock; heat compensation; salt tolerance