title: An Arabidopsis mutant defective in UV-B light-mediated responses.
abstract: In plants, low fluences of ultraviolet-B radiation (UV-B; 280-320 nm) trigger the activation of protection mechanisms and various photomorphogenic responses. We established a novel screen to isolate Arabidopsis T-DNA mutants (uli, UV-B light insensitive) with reduced sensitivity towards UV-B light-mediated inhibition of hypocotyl growth. One of the mutants, uli3, shows also a reduced sensitivity of UV-B-induced gene expression events and was, therefore, chosen for further investigation. The ULI3 gene encodes an 80-kDa protein with potential domains for heme- and diacylglycerol-binding. In transiently transfected protoplasts, the ULI3:GFP fusion protein is localised in the cytoplasm but also adjacent to membranes. In etiolated Arabidopsis seedlings irradiated by UV-B, ULI3 mRNA expression is strongly up-regulated. This is caused by elevated transcription as demonstrated using stable transformants where a GUS-reporter was driven by the ULI3-promoter. ULI3 is preferentially expressed in the outer cell layers in leaves, stems and flowers, but not in roots. There is evidence that ULI3 represents a specific component involved in UV-B-mediated signal transduction in higher plants.
authors.affiliation: Institute for Biology II/Cell Biology, University of Freiburg, Schänzlestr 1, D-79104 Freiburg, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Suesslin
authors.forename: Hanns
authors.initials: H
authors.lastname: Frohnmeyer
mesh_terms: D000872:Anthocyanins / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000528:radiation effects; D049452:Green Fluorescent Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; C473374:ULI3 protein, Arabidopsis; D049452:Green Fluorescent Proteins