Genome-wide analysis and transcript profiling identify several abiotic and biotic stress-responsive Glutathione S-transferase genes in soybean

Abiotic and biotic stresses stimulate the generation of free radicals and reactive oxygen species, which results in oxidative stress. Glutathione-S-transferase (GST) is a large class of multifunctional enzymes that exists widely in plants. The addition of reduced glutathione by GSTs protects the cell from various toxic molecules and thus provide tolerance against adverse conditions. In this study, we have performed a genome-wide identification, characterization and expression analysis of GST gene family in soybean (Glycine max) to know their function. We have identified the presence of at least 126 putative GST genes in soybean. Among them, presence of a total of 33 pairs of duplicated genes might contribute towards the expansion of GST family members in soybean. Based on the phylogenetic analysis, GmGSTs could be further subdivided into 12 classes. GmGST tau class possessed the maximum number of 68 members, followed by phi (14 members) and lambda (7 members) classes. Expression of all 126 GmGST transcripts was analyzed in 26 anatomical tissues and 7 developmental stages. Moreover, expression profiling was expanded in response to various abiotic and biotic stresses. Four genes (GmGSTU63, GmGSTU73, GmGSTF2, and GmGSTT5) were found to be highly upregulated in response to four abiotic stresses- dehydration, drought, temperature and ozone; and two biotic stress conditions. This comprehensive genome-wide analysis and expression profiling will help to understand the function of GST in adverse environmental circumstances as well as enhancing the genetic modification of soybean.