Overexpression of the UGT73C6 alters brassinosteroid glucoside formation in Arabidopsis thaliana

BMC Plant Biology

Research Article

Franz Berthiller¹  Rudolf Krska¹  Rainer Schuhmacher¹  Dianna Bowles²  Luisa Elias²  Fabian E Vaistij²  Yi Li²  Gillian S Higgins²  Sigrid Husar³  Wilfried Rozhon³  Mamoona Khan³  Florian Kalaivanan³  Brigitte Poppenberger⁴  Hideharu Seto⁵  Shozo Fujioka⁵ 

[1] Center for Analytical Chemistry, Department of Agrobiotechnology, University of Natural Resources and Life Sciences, Konrad Lorenz Straße 20, 3430, Tulln, Austria;Center for Novel Agricultural Products, Department of Biology, University of York, YO10 5DD, York, UK;Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9, 1030, Vienna, Austria;Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9, 1030, Vienna, Austria;Center for Novel Agricultural Products, Department of Biology, University of York, YO10 5DD, York, UK;RIKEN Advanced Science Institute, 351-0198, Wako-shi, Saitama, Japan;

关键词: arabidopsis;    brassinosteroids;    glycosylation;    homeostasis;    malonylation;    steroids;   

DOI  :  10.1186/1471-2229-11-51

 received in 2010-11-25, accepted in 2011-03-24,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundBrassinosteroids (BRs) are signaling molecules that play essential roles in the spatial regulation of plant growth and development. In contrast to other plant hormones BRs act locally, close to the sites of their synthesis, and thus homeostatic mechanisms must operate at the cellular level to equilibrate BR concentrations. Whilst it is recognized that levels of bioactive BRs are likely adjusted by controlling the relative rates of biosynthesis and by catabolism, few factors, which participate in these regulatory events, have as yet been identified. Previously we have shown that the UDP-glycosyltransferase UGT73C5 of Arabidopsis thaliana catalyzes 23-O-glucosylation of BRs and that glucosylation renders BRs inactive. This study identifies the closest homologue of UGT73C5, UGT73C6, as an enzyme that is also able to glucosylate BRs in planta.ResultsIn a candidate gene approach, in which homologues of UGT73C5 were screened for their potential to induce BR deficiency when over-expressed in plants, UGT73C6 was identified as an enzyme that can glucosylate the BRs CS and BL at their 23-O-positions in planta. GUS reporter analysis indicates that UGT73C6 shows over-lapping, but also distinct expression patterns with UGT73C5 and YFP reporter data suggests that at the cellular level, both UGTs localize to the cytoplasm and to the nucleus. A liquid chromatography high-resolution mass spectrometry method for BR metabolite analysis was developed and applied to determine the kinetics of formation and the catabolic fate of BR-23-O-glucosides in wild type and UGT73C5 and UGT73C6 over-expression lines. This approach identified novel BR catabolites, which are considered to be BR-malonylglucosides, and provided first evidence indicating that glucosylation protects BRs from cellular removal. The physiological significance of BR glucosylation, and the possible role of UGT73C6 as a regulatory factor in this process are discussed in light of the results presented.ConclusionThe present study generates essential knowledge and molecular and biochemical tools, that will allow for the verification of a potential physiological role of UGT73C6 in BR glucosylation and will facilitate the investigation of the functional significance of BR glucoside formation in plants.

【 授权许可】

Unknown   
© Husar et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.