Cloning and expression analysis of two salt and <I>Fusa-rium graminearum</I> stress associated UDP-glucosyltransferases genes in wheat

Glycosyltransferases (GTs) play important roles in stress responses of plants by glycosylating hormones and secondary metabolites. UDP-glucosyltransferases (UGTs), which use UDP-glucuronic acid in animals, UDP-glucose, UDP-galactose, and UDP- rhamnose in plant as sugar donors, belong to family 1 of GTs. As a secondary metabolite produced by Fusarium graminearum during infection of grains, deoxynivalenol (DON) is not only harmful to human and animal's health by inhibiting protein synthesis, but also acts as a virulence factor during fungal pathogenesis. In order to study expression profile of UGT genes in wheat, two UGTs, designated TaUGT1 and TaUGT2, were isolated from bread wheat (Triticum aestivum L.) by reverse transcriptase-polymerase chain reaction. The genomic sequences of both genes had one intron. Their coding sequences shared 91% and 90% similarities at nucleic acid level and the deduced protein sequence level. The analysis of conserved domain revealed that these two cDNAs encoded UDP-glucoronosyl and UDP-glucosyl transferase with PSPG (Putative secondary plant glycosyltransferase) domain. Real-time PCR was carried out to detect the expression profiles of the two UGTs in wheat under various stress conditions. In young spikes infected by Fusarium graminearum, TaUGT2 was induced but TaUGT1 was repressed. These two genes were upregulated under higher NaCl concentration. In conclusion, TaUGT2 may participate in wheat resistance to Fusarium head blight in which mycotoxin DON plays a role, and these two genes might be involved in responses of wheat to salt stress.