Journal Article

PHYTOCHROME C plays a major role in the acceleration of wheat flowering under long-day photoperiod

Lin, Huiqiong, Rockwell, Nathan C., Chen, Andrew, Hu, Wei, Lau, Mei Yee, Jernstedt, Judith A., Dubcovsky, Jorge, Lagarias, J. Clark, Li, Chengxia, Martin, Shelley S.

2014

Overview

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.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Active Transport, Cell Nucleus - physiology / Alleles / Arabidopsis / Arabidopsis - genetics / Arabidopsis - metabolism / Barley / Base Sequence / Biological Sciences / Cell Nucleus - genetics / Cell Nucleus - metabolism / Circadian Clocks - physiology / circadian rhythm / far-red light / Flowering / Flowering plants / flowers / Flowers - genetics / Flowers - metabolism / Gene expression regulation / Genes / Genetic mutation / Grasses / heading / homozygosity / loci / Molecular Sequence Data / mutants / Mutation / Photoperiod / phytochrome / Phytochrome - genetics / Phytochrome - metabolism / Plant species / Plants / Proteins / red light / Rice / Signal Transduction - physiology / tetraploidy / Triticum - genetics / Triticum - metabolism / Wheat