title: Phototropins maintain robust circadian oscillation of PSII operating efficiency under blue light.
abstract: The circadian system allows plants to coordinate metabolic and physiological functions with predictable environmental variables such as dusk and dawn. This endogenous oscillator is comprised of biochemical and transcriptional rhythms that are synchronized with a plant's surroundings via environmental signals, including light and temperature. We have used chlorophyll fluorescence techniques to describe circadian rhythms of PSII operating efficiency (Fq'/Fm') in the chloroplasts of Arabidopsis thaliana. These Fq'/Fm' oscillations appear to be influenced by transcriptional feedback loops previously described in the nucleus, and are induced by rhythmic changes in photochemical quenching over circadian time. Our work reveals that a family of blue photoreceptors, phototropins, maintain robust rhythms of Fq'/Fm' under constant blue light. As phototropins do not influence circadian gene expression in the nucleus our imaging methodology highlights differences between the modulation of circadian outputs in distinct subcellular compartments.
authors.affiliation: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Litthauer
authors.affiliation: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK.
authors.forename: Martin W
authors.initials: MW
authors.lastname: Battle
authors.affiliation: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK.
authors.forename: Tracy
authors.initials: T
authors.lastname: Lawson
authors.affiliation: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK.
authors.forename: Matthew A
authors.identifier: http://orcid.org/0000-0002-3943-3968
authors.initials: MA
authors.lastname: Jones
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll; D000077194:Chlorophyll A; D002940:Circadian Rhythm / Q000502:physiology; D005453:Fluorescence; D008027:Light; D009154:Mutation; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism*; D056949:Phototropins / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; C400222:NPH3 protein, Arabidopsis; C423903:PHOT2 protein, Arabidopsis; C523308:PRR7 protein, Arabidopsis; D010750:Phosphoproteins; D045332:Photosystem II Protein Complex; D056949:Phototropins; D012097:Repressor Proteins; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors; D002734:Chlorophyll; C103646:NPH1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D000077194:Chlorophyll A
keywords: Arabidopsis thaliana; PSII operating efficiency; chlorophyll fluorescence; chloroplast; circadian rhythms; phototropin