title: PSEUDO RESPONSE REGULATORs stabilize CONSTANS protein to promote flowering in response to day length.
abstract: Seasonal reproduction in many organisms requires detection of day length. This is achieved by integrating information on the light environment with an internal photoperiodic time-keeping mechanism.Arabidopsis thalianapromotes flowering in response to long days (LDs), and CONSTANS (CO) transcription factor represents a photoperiodic timer whose stability is higher when plants are exposed to light under LDs. Here, we show that PSEUDO RESPONSE REGULATOR (PRR) proteins directly mediate this stabilization. PRRs interact with and stabilize CO at specific times during the day, thereby mediating its accumulation under LDs. PRR-mediated stabilization increases binding of CO to the promoter ofFLOWERING LOCUS T(FT), leading to enhancedFTtranscription and early flowering under these conditions. PRRs were previously reported to contribute to timekeeping by regulatingCOtranscription through their roles in the circadian clock. We propose an additional role for PRRs in which they act upon CO protein to promote flowering, directly coupling information on light exposure to the timekeeper and allowing recognition of LDs.
authors.affiliation: Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Hayama
authors.affiliation: Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
authors.forename: Liron
authors.initials: L
authors.lastname: Sarid-Krebs
authors.affiliation: Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Richter
authors.affiliation: Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
authors.forename: Virginia
authors.initials: V
authors.lastname: Fernández
authors.affiliation: Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
authors.forename: Seonghoe
authors.initials: S
authors.lastname: Jang
authors.affiliation: Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany coupland@mpipz.mpg.de.
authors.forename: George
authors.identifier: 0000-0001-6988-4172
authors.initials: G
authors.lastname: Coupland
mesh_terms: D017360:Arabidopsis / Q000502:physiology* / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D035264:Flowers / Q000528:radiation effects*; D008027:Light; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C092776:CONSTANS protein, Arabidopsis; D004268:DNA-Binding Proteins; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors
keywords: 
  Arabidopsis
  ; CONSTITUTIVE PHOTOMORPHOGENIC 1; PSEUDO RESPONSE REGULATOR; circadian clock; photoperiodic flowering