Validation of a Candidate Deoxynivalenol-Inactivating UDP-Glucosyltransferase from Barley by Heterologous Expression in Yeast

Resistance to the virulence factor deoxynivalenol (DON) due to formation of DON-3-O-glucoside (D3G) is considered to be an important component of resistance against Fusarium spp. which produce this toxin. Multiple candidate UDP-glycosyltransferase (UGT) genes from different crop plants that are either induced by Fusariutn spp. or differentially expressed in cultivars varying in Fusarium disease resistance have been described. However, UGT are encoded by a very large gene family in plants. The study of candidate plant UGT is highly warranted because of the potential relevance for developing Fusarium-spp.-resistant crops. We tested Arahidopsis thaliana genes closely related to a previously identified DON-glucosyltransferase gene by heterologous expression in yeast and showed that gene products with very high sequence similarity can have pronounced differences in detoxification capabilities. We also tested four candidate barley glucosyltransferases, which are highly DON inducible. Upon heterologous expression of full-length cDNAs, only one gene, HvUGT13248, conferred DON resistance. The conjugate D3G accumulated in the supernatant of DON-treated yeast transformants. We also present evidence that the product of the TaUGT3 gene recently proposed to encode a DON-detoxification enzyme of wheat does not protect yeast against DON.