TransgenicArabidopsis thalianaexpressing a barley UDP-glucosyltransferase exhibit resistance to the mycotoxin deoxynivalenol

Fusarium head blight (FHB), caused byFusarium graminearum, is a devastating disease of small grain cereal crops. FHB causes yield reductions and contamination of grain with trichothecene mycotoxins such as deoxynivalenol (DON). DON inhibits protein synthesis in eukaryotic cells and acts as a virulence factor during fungal pathogenesis, therefore resistance to DON is considered an important component of resistance against FHB. One mechanism of resistance to DON is conversion of DON to DON-3-O-glucoside (D3G). Previous studies showed that expression of the UDP-glucosyltransferase genesHvUGT13248from barley andAtUGt73C5(DOGT1) fromArabidopsis thalianaconferred DON resistance to yeast. Over-expression ofAtUGt73C5inArabidopsisled to increased DON resistance of seedlings but also to dwarfing of transgenic plants due to the formation of brassinosteroid-glucosides. The objectives of this study were to develop transgenicArabidopsisexpressingHvUGT13248, to test for phenotypic changes in growth habit, and the response to DON. Transgenic lines that constitutively expressed the epitope-tagged HvUGT13248 protein exhibited increased resistance to DON in a seed germination assay and converted DON to D3G to a higher extent than the untransformed wild-type. By contrast to the over-expression ofDOGT1inArabidopsis, which conjugated the brassinosteriod castasterone with a glucoside group resulting in a dwarf phenotype, expression of the barleyHvUGT13248gene did not lead to drastic morphological changes. Consistent with this observation, no castasterone-glucoside formation was detectable in yeast expressing the barleyHvUGT13248gene. This barleyUGTis therefore a promising candidate for transgenic approaches aiming to increase DON andFusariumresistance of crop plants without undesired collateral effects.