title: REPRESSOR OF ULTRAVIOLET-B PHOTOMORPHOGENESIS function allows efficient phototropin mediated ultraviolet-B phototropism in etiolated seedlings.
abstract: Ultraviolet B (UV-B) light is a part of the solar radiation which has significant effects on plant morphology, even at low doses. In Arabidopsis, many of these morphological changes have been attributed to a specific UV-B receptor, UV resistance locus 8 (UVR8). Recent findings showed that next to phototropin regulated phototropism, UVR8 mediated signaling is able of inducing directional bending towards UV-B light in etiolated seedlings of Arabidopsis, in a phototropin independent manner. In this study, kinetic analysis of phototropic bending was used to evaluate the relative contribution of each of these pathways in UV-B mediated phototropism. Diminishing UV-B light intensity favors the importance of phototropins. Molecular and genetic analyses suggest that UV-B is capable of inducing phototropin signaling relying on phototropin kinase activity and regulation of NPH3. Moreover, enhanced UVR8 responses in the UV-B hypersensitive rup1rup2 mutants interferes with the fast phototropin mediated phototropism. Together the data suggest that phototropins are the most important receptors for UV-B induced phototropism in etiolated seedlings, and a RUP mediated negative feedback pathway prevents UVR8 signaling to interfere with the phototropin dependent response.
authors.affiliation: Laboratory of Functional Plant Biology, Department of Physiology, Faculty of Sciences, Ghent University, KL Ledeganckstraat 35, B-9000 Gent, Belgium.
authors.forename: Lucas
authors.initials: L
authors.lastname: Vanhaelewyn
authors.affiliation: Center for Integrative Genomics, Faculty of Biology and Medicine, Université de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Paolo
authors.initials: P
authors.lastname: Schumacher
authors.affiliation: Lumilab, Department of Solid State Sciences, Faculty of Sciences, Ghent University, Krijgslaan 181, B-9000 Gent, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Poelman
authors.affiliation: Center for Integrative Genomics, Faculty of Biology and Medicine, Université de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Fankhauser
authors.affiliation: Laboratory of Functional Plant Biology, Department of Physiology, Faculty of Sciences, Ghent University, KL Ledeganckstraat 35, B-9000 Gent, Belgium.
authors.forename: Dominique
authors.initials: D
authors.lastname: Van Der Straeten
authors.affiliation: Laboratory of Functional Plant Biology, Department of Physiology, Faculty of Sciences, Ghent University, KL Ledeganckstraat 35, B-9000 Gent, Belgium. Electronic address: Filip.Vandenbussche@ugent.be.
authors.forename: Filip
authors.initials: F
authors.lastname: Vandenbussche
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D007700:Kinetics; D055537:Light Signal Transduction; D056949:Phototropins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018524:Phototropism; D036226:Seedlings / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; D002868:Chromosomal Proteins, Non-Histone; D056949:Phototropins; C525052:Uvr8 protein, Arabidopsis
keywords: Arabidopsis; Light; Phototropism; UV-B; Ultraviolet