title: Promotion of photomorphogenesis by COP1.
abstract: CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) represses photomorphogenesis in darkness by targeting nuclear-localized transcription factors to proteasome-mediated degradation. Upon light exposure, COP1 migrates to the cytosol allowing photomorphogenesis to proceed but the residual nuclear pool down-regulates light signaling mediated by phytochrome A. Here we show that weak alleles of cop1 exhibit reverse photomorphogenic responses i.e. reduced rather than enhanced cotyledon unfolding under red light compared to darkness. Conversely, COP1 overexpressors which de-etiolate poorly under blue or far-red light, showed enhanced photomorphogenesis under red light. The positive relationship between COP1 and photomorphogenic response required phytochrome B. Thus, genetic manipulation of COP1 levels differentially affects phytochrome A- compared to phytochrome B-mediated responses. We hypothesize that COP1 could be involved in degradation of negative regulators of photomorphogenesis or in transcriptional activation, as observed for some E3 ligases in mammalian development.
authors.affiliation: I.F.E.V.A., Faculty of Agronomy, University of Buenos Aires, Av. San Martín 4453, 1417, Buenos Aires, Argentina.
authors.forename: Hernán E
authors.initials: HE
authors.lastname: Boccalandro
authors.forename: María C
authors.initials: MC
authors.lastname: Rossi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Saijo
authors.forename: Xing-Wang
authors.initials: XW
authors.lastname: Deng
authors.forename: Jorge J
authors.initials: JJ
authors.lastname: Casal
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D009024:Morphogenesis / Q000235:genetics / Q000528:radiation effects*; D009154:Mutation; D010786:Photoreceptor Cells / Q000502:physiology; D010834:Phytochrome / Q000235:genetics / Q000502:physiology; D051942:Phytochrome A; D051939:Phytochrome B; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; C497973:PHYA protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; D051942:Phytochrome A; D014157:Transcription Factors; D010834:Phytochrome; D051939:Phytochrome B; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases; D017346:Protein Serine-Threonine Kinases