Photoreceptor-mediated bending towards UV-B in Arabidopsis.
Plants reorient their growth towards light to optimize photosynthetic light capture--a process known as phototropism. Phototropins are the photoreceptors essential for phototropic growth towards blue and ultraviolet-A (UV-A) light. Here we detail a phototropic response towards UV-B in etiolated Arabidopsis seedlings. We report that early differential growth is mediated by phototropins but clear phototropic bending to UV-B is maintained in phot1 phot2 double mutants. We further show that this phototropin-independent phototropic response to UV-B requires the UV-B photoreceptor UVR8. Broad UV-B-mediated repression of auxin-responsive genes suggests that UVR8 regulates directional bending by affecting auxin signaling. Kinetic analysis shows that UVR8-dependent directional bending occurs later than the phototropin response. We conclude that plants may use the full short-wavelength spectrum of sunlight to efficiently reorient photosynthetic tissue with incoming light.
Laboratory of Functional Plant Biology, Department of Physiology, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium. Electronic address: Filip.Vandenbussche@ugent.be.
Filip
F
Vandenbussche
Department of Botany and Plant Biology, Sciences III, University of Geneva, CH-1211 Geneva 4, Switzerland.
Kimberley
K
Tilbrook
Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, B-3001, Heverlee, Belgium.
Ana Carolina
AC
Fierro
Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, KU Leuven, B-3001, Heverlee, Belgium; Department of Plant Biotechnology and Bioinformatics, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium; Department of Information Technology, IMinds, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium.
Kathleen
K
Marchal
Lumilab, Department of Solid State Sciences, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium.
Dirk
D
Poelman
Laboratory of Functional Plant Biology, Department of Physiology, Faculty of Sciences, Ghent University, B-9000 Ghent, Belgium.
Dominique
D
Van Der Straeten
Department of Botany and Plant Biology, Sciences III, University of Geneva, CH-1211 Geneva 4, Switzerland.
Roman
R
Ulm
D017360:Arabidopsis / Q000378:metabolism* / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D018524:Phototropism / Q000502:physiology*; D014466:Ultraviolet Rays
D029681:Arabidopsis Proteins
Arabidopsis.; UV-B; UVR8; auxin; phototropism