title: Phytochrome C plays a major role in the acceleration of wheat flowering under long-day photoperiod.
abstract: Phytochromes are dimeric proteins that function as red and far-red light sensors influencing nearly every phase of the plant life cycle. Of the three major phytochrome families found in flowering plants, phytochrome C (PHYC) is the least understood. In Arabidopsis and rice, PHYC is unstable and functionally inactive unless it heterodimerizes with another phytochrome. However, when expressed in an Arabidopsis phy-null mutant, wheat PHYC forms signaling active homodimers that translocate into the nucleus in red light to mediate photomorphogenic responses. Tetraploid wheat plants homozygous for loss-of-function mutations in all PHYC copies (phyC(AB)) flower on average 108 d later than wild-type plants under long days but only 19 d later under short days, indicating a strong interaction between PHYC and photoperiod. This interaction is further supported by the drastic down-regulation in the phyC(AB) mutant of the central photoperiod gene photoperiod 1 (PPD1) and its downstream target flowering locus T1, which are required for the promotion of flowering under long days. These results implicate light-dependent, PHYC-mediated activation of PPD1 expression in the acceleration of wheat flowering under inductive long days. Plants homozygous for the phyC(AB) mutations also show altered profiles of circadian clock and clock-output genes, which may also contribute to the observed differences in heading time. Our results highlight important differences in the photoperiod pathways of the temperate grasses with those of well-studied model plant species.
authors: Departments of Plant Sciences and.
authors: Andrew
authors: A
authors: Chen
authors: Departments of Plant Sciences andHoward Hughes Medical Institute, Chevy Chase, MD 20815.
authors: Chengxia
authors: C
authors: Li
authors: Molecular and Cellular Biology, University of California, Davis, CA 95616; and.
authors: Wei
authors: W
authors: Hu
authors: Departments of Plant Sciences and.
authors: Mei Yee
authors: MY
authors: Lau
authors: Departments of Plant Sciences and.
authors: Huiqiong
authors: H
authors: Lin
authors: Molecular and Cellular Biology, University of California, Davis, CA 95616; and.
authors: Nathan C
authors: NC
authors: Rockwell
authors: Molecular and Cellular Biology, University of California, Davis, CA 95616; and.
authors: Shelley S
authors: SS
authors: Martin
authors: Departments of Plant Sciences and.
authors: Judith A
authors: JA
authors: Jernstedt
authors: Molecular and Cellular Biology, University of California, Davis, CA 95616; and jdubcovsky@ucdavis.edu jclagarias@ucdavis.edu.
authors: J Clark
authors: JC
authors: Lagarias
authors: Departments of Plant Sciences andHoward Hughes Medical Institute, Chevy Chase, MD 20815 jdubcovsky@ucdavis.edu jclagarias@ucdavis.edu.
authors: Jorge
authors: J
authors: Dubcovsky
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D057906:Circadian Clocks / Q000502:physiology*; D035264:Flowers / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D017440:Photoperiod; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D014908:Triticum / Q000235:genetics / Q000378:metabolism*
chemical_list: D010834:Phytochrome
keywords: TILLING; development; ethyl methane sulphonate; flowering time; temperate cereals