UV-B action spectrum for UVR8-mediated HY5 transcript accumulation in Arabidopsis.
Arabidopsis thaliana UV RESISTANCE LOCUS8 (UVR8) is a UV-B-specific signaling component that mediates low fluence, photomorphogenic responses to UV-B. It is required for UV-B-induced expression of the gene encoding the ELONGATED HYPOCOTYL5 (HY5) transcription factor. HY5 is a key effector of responses mediated by UVR8. In mature leaf tissue, HY5 transcript accumulation occurred rapidly in response to a brief UV-B treatment and no induction was observed in a uvr8 mutant over a broad range of UV wavelengths. In response to monochromatic light, maximal transcript accumulation occurred in wild-type plants at wavelengths 280-300 nm. HY5 transcript accumulation showed reciprocity between the fluence rate and duration of UV-B exposure, and on this basis conditions were chosen to generate an action spectrum for the UVR8 signaling pathway. Dose-response curves were produced for a range of UV wavelengths using 20 min exposure to UV and harvesting tissue 2 h after the start of illumination. Experiments using mutants defective in sinapate ester and flavonoid biosynthesis indicated that the presence of UV-absorbing compounds did not affect the construction of an action spectrum under the conditions employed. The action spectrum for the induction of HY5 by the UVR8 pathway showed a main peak at 280 nm with a smaller peak at 300 nm. The data are discussed in relation to the proposed mechanisms of UV-B photoreception.
Brown
Bobby A
BA
Plant Science Group, Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK.
Headland
Lauren R
LR
Jenkins
Gareth I
GI
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics*; D017931:DNA Primers; D009687:Nuclear Proteins / Q000235:genetics*; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D014466:Ultraviolet Rays
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D017931:DNA Primers; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; D012333:RNA, Messenger