title: Distinct light and clock modulation of cytosolic free Ca2+ oscillations and rhythmic CHLOROPHYLL A/B BINDING PROTEIN2 promoter activity in Arabidopsis.
abstract: Plants have circadian oscillations in the concentration of cytosolic free calcium ([Ca(2+)](cyt)). To dissect the circadian Ca(2+)-signaling network, we monitored circadian [Ca(2+)](cyt) oscillations under various light/dark conditions (including different spectra) in Arabidopsis thaliana wild type and photoreceptor and circadian clock mutants. Both red and blue light regulate circadian oscillations of [Ca(2+)](cyt). Red light signaling is mediated by PHYTOCHROME B (PHYB). Blue light signaling occurs through the redundant action of CRYPTOCHROME1 (CRY1) and CRY2. Blue light also increases the basal level of [Ca(2+)](cyt), and this response requires PHYB, CRY1, and CRY2. Light input into the oscillator controlling [Ca(2+)](cyt) rhythms is gated by EARLY FLOWERING3. Signals generated in the dark also regulate the circadian behavior of [Ca(2+)](cyt). Oscillations of [Ca(2+)](cyt) and CHLOROPHYLL A/B BINDING PROTEIN2 (CAB2) promoter activity are dependent on the rhythmic expression of LATE ELONGATED HYPOCOTYL and CIRCADIAN CLOCK-ASSOCIATED1, but [Ca(2+)](cyt) and CAB2 promoter activity are uncoupled in the timing of cab1 (toc1-1) mutant but not in toc1-2. We suggest that the circadian oscillations of [Ca(2+)](cyt) and CAB2 promoter activity are regulated by distinct oscillators with similar components that are used in a different manner and that these oscillators may be located in different cell types in Arabidopsis.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, Nashville, Tenessee 37235, USA.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xu
authors.forename: Carlos T
authors.initials: CT
authors.lastname: Hotta
authors.forename: Antony N
authors.initials: AN
authors.lastname: Dodd
authors.forename: John
authors.initials: J
authors.lastname: Love
authors.forename: Robert
authors.initials: R
authors.lastname: Sharrock
authors.forename: Young Wha
authors.initials: YW
authors.lastname: Lee
authors.forename: Qiguang
authors.initials: Q
authors.lastname: Xie
authors.forename: Carl H
authors.initials: CH
authors.lastname: Johnson
authors.forename: Alex A R
authors.initials: AA
authors.lastname: Webb
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001683:Biological Clocks / Q000528:radiation effects*; D020013:Calcium Signaling / Q000528:radiation effects*; D002352:Carrier Proteins / Q000235:genetics*; D002940:Circadian Rhythm / Q000528:radiation effects*; D056931:Cryptochromes; D003600:Cytosol / Q000378:metabolism / Q000528:radiation effects; D005420:Flavoproteins / Q000378:metabolism; D008027:Light; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010834:Phytochrome / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D036226:Seedlings / Q000502:physiology / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; C423618:CAB2 protein, Arabidopsis; C538962:CRY1 protein, Arabidopsis; D002352:Carrier Proteins; D056931:Cryptochromes; D005420:Flavoproteins; D045342:Light-Harvesting Protein Complexes; D010834:Phytochrome