Maria Paula Kovalsky
Klaus F. X.
1Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, A-3430 Tulln, Austria; 2Institut de Biologie des Plantes, Bâtiment 630, Université Paris Sud, F-91405 Orsay Cedex France; 3Munich Information Center for Protein Sequences/Institute for Bioinformatics and Systems Biology, Helmholtz Center Munich, D-85764 Neuherberg, Germany; 4Institute for Biotechnology in Plant Production and 5Christian Doppler Laboratory for Mycotoxin Metabolism, Department for Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, A-3430 Tulln, Austria
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Accepted 26 March 2013.
Plant small-molecule UDP-glycosyltransferases (UGT) glycosylate a vast number of endogenous substances but also act in detoxification of metabolites produced by plant-pathogenic microorganisms. The ability to inactivate the Fusarium graminearum mycotoxin deoxynivalenol (DON) into DON-3-O-glucoside is crucial for resistance of cereals. We analyzed the UGT gene family of the monocot model species Brachypodium distachyon and functionally characterized two gene clusters containing putative orthologs of previously identified DON-detoxification genes from Arabidopsis thaliana and barley. Analysis of transcription showed that UGT encoded in both clusters are highly inducible by DON and expressed at much higher levels upon infection with a wild-type DON-producing F. graminearum strain compared with infection with a mutant deficient in DON production. Expression of these genes in a toxin-sensitive strain of Saccharomyces cerevisiae revealed that only two B. distachyon UGT encoded by members of a cluster of six genes homologous to the DON-inactivating barley HvUGT13248 were able to convert DON into DON-3-O-glucoside. Also, a single copy gene from Sorghum bicolor orthologous to this cluster and one of three putative orthologs of rice exhibit this ability. Seemingly, the UGT genes undergo rapid evolution and changes in copy number, making it difficult to identify orthologs with conserved substrate specificity.
© 2013 The American Phytopathological Society