title: Regulation of photoperiodic flowering by Arabidopsis photoreceptors.
abstract: Photoperiodism is a day-length-dependent seasonal change of physiological or developmental activities that is widely found in plants and animals. Photoperiodic flowering in plants is regulated by photosensory receptors including the red/far-red light-receptor phytochromes and the blue/UV-A light-receptor cryptochromes. However, the molecular mechanisms underlying the specific roles of individual photoreceptors have remained poorly understood. Here, we report a study of the day-length-dependent response of cryptochrome 2 (cry2) and phytochrome A (phyA) and their role as day-length sensors in Arabidopsis. The protein abundance of cry2 and phyA showed a diurnal rhythm in plants grown in short-day but not in plants grown in long-day. The short-day-specific diurnal rhythm of cry2 is determined primarily by blue light-dependent cry2 turnover. Consistent with a proposition that cry2 and phyA are the major day-length sensors in Arabidopsis, we show that phyA mediates far-red light promotion of flowering with modes of action similar to that of cry2. Based on these results and a finding that the photoperiodic responsiveness of plants depends on light quality, a model is proposed to explain how individual phytochromes and cryptochromes work together to confer photoperiodic responsiveness in Arabidopsis.
authors.affiliation: Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095, USA.
authors.forename: Todd
authors.initials: T
authors.lastname: Mockler
authors.forename: Hongyun
authors.initials: H
authors.lastname: Yang
authors.forename: XuHong
authors.initials: X
authors.lastname: Yu
authors.forename: Dhavan
authors.initials: D
authors.lastname: Parikh
authors.forename: Ying-chia
authors.initials: YC
authors.lastname: Cheng
authors.forename: Sarah
authors.initials: S
authors.lastname: Dolan
authors.forename: Chentao
authors.initials: C
authors.lastname: Lin
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins; D002940:Circadian Rhythm; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000502:physiology*; D008027:Light; D017440:Photoperiod; D017956:Photoreceptor Cells, Invertebrate; D010834:Phytochrome / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled
chemical_list: D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila; D010834:Phytochrome