The out of phase 1 mutant defines a role for PHYB in circadian phase control in Arabidopsis.
Arabidopsis displays circadian rhythms in stomatal aperture, stomatal conductance, and CO(2) assimilation, each of which peaks around the middle of the day. The rhythmic opening and closing of stomata confers a rhythm in sensitivity and resistance, respectively, to the toxic gas sulfur dioxide. Using this physiological assay as a basis for a mutant screen, we isolated mutants with defects in circadian timing. Here, we characterize one mutant, out of phase 1 (oop1), with the circadian phenotype of altered phase. That is, the timing of the peak (acrophase) of multiple circadian rhythms (leaf movement, CO(2) assimilation, and LIGHT-HARVESTING CHLOROPHYLL a/b-BINDING PROTEIN transcription) is early with respect to wild type, although all circadian rhythms retain normal period length. This is the first such mutant to be characterized in Arabidopsis. oop1 also displays a strong photoperception defect in red light characteristic of phytochrome B (phyB) mutants. The oop1 mutation is a nonsense mutation of PHYB that results in a truncated protein of 904 amino acids. The defect in circadian phasing is seen in seedlings entrained by a light-dark cycle but not in seedlings entrained by a temperature cycle. Thus, PHYB contributes light information critical for proper determination of circadian phase.
Salomé
Patrice A
PA
Department of Biological Sciences, 6044 Gilman Laboratories, Dartmouth College, Hanover, New Hampshire 03755-3576, USA.
Michael
Todd P
TP
Kearns
Ellen V
EV
Fett-Neto
Arthur G
AG
Sharrock
Robert A
RA
McClung
C Robertson
CR
D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins; D001483:Base Sequence; D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D018546:Hypocotyl / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D045342:Light-Harvesting Protein Complexes; D009154:Mutation; D010786:Photoreceptor Cells; D045322:Photosynthetic Reaction Center Complex Proteins / Q000187:drug effects / Q000528:radiation effects; D010834:Phytochrome / Q000502:physiology*; D051939:Phytochrome B; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D013458:Sulfur Dioxide / Q000494:pharmacology; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000187:drug effects / Q000528:radiation effects
D029681:Arabidopsis Proteins; D045342:Light-Harvesting Protein Complexes; C497952:PHYB protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D014157:Transcription Factors; D013458:Sulfur Dioxide; D010834:Phytochrome; D051939:Phytochrome B; D002734:Chlorophyll; D002245:Carbon Dioxide