Effects of the wheat UDP-glucosyltransferase gene TaUGT-B2 on Agrobacterium-mediated plant transformation

Abstract

UDP-glucosyltransferase enzymes (UGTs) are known to function in plant disease defense responses. In our previous RNA-seq analysis, TaUGT expression was found to be strongly up-regulated in Agrobacterium-infected wheat immature embryos, as compared to untreated controls. In this study, we isolated the TaUGT-B2, located on wheat 2BS chromosome, and characterized its function in tobacco, Arabidopsis, and wheat. Transient overexpression of TaUGT-B2 reduced the number of Agrobacterium cells attached to the surface of wheat cells, and hindered Agrobacterium-mediated GUS transient expression in wheat cells. Transiently silenced TaUGT-B2 expression resulted in an increased rate of shoot regeneration from Agrobacterium-infected wheat tissues. Therefore, we concluded that the overexpression of TaUGT-B2 impeded T-DNA transformation by reducing number of Agrobacterium cells attached to wheat tissues and lowering the regeneration efficiency of transgenic plantlets. In order to further investigate the function of TaUGT-B2, it was introduced into tobacco and Arabidopsis, and transgenic plants were then re-transformed with another vector carrying the GUS gene. The results of these experiments indicated that the expression of TaUGT-B2 in tobacco and Arabidopsis led to a reduction in the efficiency of Agrobacterium-mediated transformation. GUS transient expression was also impeded following overexpression of TaUGT-B2 in tobacco and Arabidopsis. Therefore, we conclude that TaUGT-B2 plays a negative role in Agrobacterium-mediated transformation of plants, especially in wheat.