Genome-wide characterization of the glutathione S-transferase gene family in Phaseolus vulgaris reveals insight into the roles of their members in responses to multiple abiotic stresses

Glutathione S-transferases (GSTs) are a class of multifunctional enzymatic antioxidants that play a significant role in several aspects of plant physiology, including growth, development, and cellular protection from biotic and abiotic stressors. A total of 59 GST genes were found in Phaseolus vulgaris genome, which were categorized into 11 distinct classes according to their evolutionary connection and the existence of conserved structural domains and motifs. Gene duplication analysis revealed that the evolution of the members of the GST gene family in P. vulgaris was driven by both segmental and tandem duplication events. Analysis of the expression profiles of identified PvGST genes using the available transcriptome data demonstrated notable expression patterns and organ specificity of many genes throughout several developmental stages and under drought or salinity. Subsequent RT-qPCR analysis of several drought-responsive or salinity-responsive candidate genes showed that PvGSTF4 was up-regulated solely by drought, PvGSTU11 was up-regulated only by salinity, and PvGSTU3, PvGSTU12, PvGSTU13, PvGSTU14, PvGSTU16, PvGSTT1, and PvGSTZ2 were up-regulated by both salt and drought. The up-regulated PvGSTs under drought and/or salinity might enable P. vulgaris to adapt to stressful environments. These candidate genes could be explored in genetic engineering programs for development of stress-tolerant P. vulgaris varieties.