Genome-Wide Analysis and Characterization of the TRX Gene Family in Upland Cotton

Thioredoxins (TRX) are small molecules of proteins that are present in all organisms. TRXs play an important role in diverse functions of plant growth and development. In this study, we performed genome-wide, characterization and expression levels of TRX gene family in cotton. A total of 150 GhTRX proteins were identified in upland cotton and classified into five subfamilies based on their domain compositions. Phylogenetic tree analysis divided TRX genes into seven subgroups. GhTRX genes covered all upland cotton chromosomes, with duplicated gene events. Ka/Ks ratio of three gene pairs was less than 1, suggesting purifying selection. The functions of GhTRX genes were studied using gene ontology, protein localization, and promoter analysis. Furthermore, six GhTRX genes were randomly selected to examine their expression level in cotton development and under various exogenous treatments. The genes showed high expressions in various tissues and at different stages of leaf senescence, also showed high expression under abscisic acid, ethylene, drought, and salinity. This study reveals the first report of TRX family genes in upland cotton. However further studies are needed to elucidate their specific functions in cotton plant.