The out of phase 1 Mutant Defines a Role for PHYB in Circadian Phase Control in Arabidopsis

• Published in: Plant physiology (Bethesda) 2002-08, Vol.129 (4), p.1674-1685
• Main Authors: Salomé, Patrice A., Michael, Todd P., Ellen V. Kearns, Arthur G. Fett-Neto, Sharrock, Robert A., McClung, C. Robertson
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - drug effects; Adaptation, Physiological - genetics; Adaptation, Physiological - radiation effects; Alleles; Amino acids; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins; Base Sequence; Biological and medical sciences; Carbon Dioxide - metabolism; Cell Biology and Signal Transduction; Cell physiology; Chlorophyll - metabolism; Circadian rhythm; Circadian Rhythm - physiology; Circadian rhythms; Fundamental and applied biological sciences. Psychology; Genes; Genetic mutation; Hypocotyl - drug effects; Hypocotyl - growth & development; Hypocotyl - radiation effects; Hypocotyls; Light; Light-Harvesting Protein Complexes; Molecular and cellular biology; Mutants; Mutation; Phenotypes; Photoreceptor Cells; Photosynthetic Reaction Center Complex Proteins - drug effects; Photosynthetic Reaction Center Complex Proteins - radiation effects; Physical agents; Phytochrome - physiology; Phytochrome B; Plant cells; Plant Leaves - drug effects; Plant Leaves - growth & development; Plant Leaves - radiation effects; Plant physiology and development; Plants; Seedlings; Stomata; Stomatal conductance; Sulfur; Sulfur dioxide; Sulfur Dioxide - pharmacology; Transcription Factors; Transcription, Genetic - drug effects; Transcription, Genetic - radiation effects; Vegetative apparatus, growth and morphogenesis. Senescence; Vision, photoreception
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.003418

Arabidopsis displays circadian rhythms in stomatal aperture, stomatal conductance, and CO2 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, CO2 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.