Genome-wide ascertainment and initial functional characterization and expression pattern dissection of the GT92 gene family in cotton

The glycosyltransferase 92 (GT92) gene belongs to the glycosyltransferase gene family. In the plant genome, it is one of the numerous genes involved in sugar metabolism and glycosylation modification. Nonetheless, the GT92 sub-family assumes a vital function in facilitating plants' adaptation to adverse environments and modulating plant growth, development, and the processes of organogenesis. To date, comprehensive characterization and systematic investigation of GT92 in cotton remain underexplored. In this study, we systematically analyzed the structural features, phylogenetic tree, gene architecture, expression profiles, evolutionary relationships, and selective pressures of GT92 gene family members across four Gossypium species using bioinformatics approaches for the first time. Collectively, 44 GT92 genes were identified, including 14 in G. hirsutum. Based on the phylogenetic tree, GT92 protein sequences from the four cotton species were clustered into five distinct subfamilies. Chromosomal mapping of these genes was performed, and their structural details were visualized. We further predicted cis-acting elements in G. hirsutum GT92 genes and characterized duplication patterns across the four Gossypium species. Ka/Ks ratios of orthologous gene pairs were calculated to investigate selective pressures among the species. RNA-seq data from G. hirsutum and G. barbadense revealed GT92 expression patterns. WGCNA (Weighted Gene Co-expression Network Analysis) identified GhGT92₅ and GhGT92₆ as members of the MEtan module, which was significantly negatively correlated with the 6-hour time point post-drought stress. Mfuzz trend analysis classified GhGT92₅ and GhGT92₆ into Cluster13 and Cluster14, respectively. qRT-PCR validated their roles under drought and salt stress conditions. Subcellular localization showed GhGT92₅ primarily distributed in the plasma membrane and chloroplasts, while GhGT92₆ was localized in the endoplasmic reticulum and chloroplasts. All of these findings have expanded our understanding of the GT92 family members, establishing a basis for more in-depth exploration of the stress-tolerance mechanisms of this gene in cotton.