Genome-wide characterization of Solanum tuberosum UGT gene family and functional analysis of StUGT178 in salt tolerance

UDP-glycosyltransferases (UGTs) widely exist in plants and play essential roles in catalyzing the glycosylation reaction associated with metabolic processes. UGT gene family has been identified in many species to date. However, the comprehensive identification and systematic analysis have not been documented yet in the latest potato genome. In this study, a total of 295 UGT members (StUGT) were identified and found to be unevenly distributed on twelve chromosomes of potato. All StUGT genes were classified into 17 groups (A-P, R) and the UGT genes within the same groups have similar structural characterization. Tandem duplication was the major driving force for the StUGT gene expansion. The prediction of cis-acting elements showed that the development process, light, phytohormone, and abiotic stress-responsive elements generally existed in StUGT promoter regions. Analysis of spatial and temporal expression patterns demonstrated that StUGT genes were widely and differentially expressed in various tissues. Additionally, to investigate the salt stress-responsive genes, we analyzed the expression profiles of the StUGT genes under salt treatment. A total of 50 and 20 StUGT genes were continuously up- and down-regulated, respectively, implicating that these genes were involved in the regulation of salt tolerance. Among them, the StUGT178 gene, which was significantly induced by salt stress and contains salt-responsive element, was considered as one of the most relevant candidate genes. Transient transformation of the StUGT178 promoter in tobacco revealed that the transcriptional activation activity of the StUGT178 gene was strengthened under salt treatment. Furthermore, the heterologous expressions of the promoter and coding protein of the StUGT178 gene in Arabidopsis further demonstrated that the StUGT178 gene significantly responds to salt treatment, and enhanced salinity tolerance by regulating antioxidant enzyme activity and H₂O₂ accumulation. These results provide comprehensive information for a better understanding of the StUGT genes and offer a foundation for uncovering their function associated with salt stress in potato.