Genome-wide analysis of Glutathione peroxidase (GPX) gene family in Chickpea (Cicer arietinum L.) under salinity stress

Chickpea is the second most widely grown legume in the world. Its cultivation is highly affected by saline soils. Salt stress damages its all growth stages from germination to maturity. It has a huge genetic diversity containing adaptation loci that can help produce salt-tolerant cultivars. The glutathione peroxidase (GPX) gene family plays an important role in regulating plant response to abiotic stimuli and protects cells from oxidative damage. In current research, the role of GPX genes is studied for inducing salt tolerance in chickpea. This study identifies the GPX gene family in Cicer arietinum. In response to the NaCl stress, the gene expression profiles of CaGPX3 were examined using real-time qRT-PCR. The results of phylogenetic analysis show that CaGPX genes have an evolutionary relationship with monocots, dicots, chlorophytes, and angiosperms. Gene structure analysis showed that CaGPX3, CaGPX4, and CaGPX5 have six, CaGPX2 has five, and CaGPX1 contains 9 exons. According to the Ka and Ks analysis chickpea has one pair of duplicated genes of GPX and the duplication was tandem with negative (purifying) selection Ka < Ks (<1). In-silico gene expression analysis revealed that CaGPX3 is a salt stress-responsive gene among all other five GPX members in chickpea. The qRT-PCR results showed that the CaGPX3 gene expression was co-ordinately regulated under salt stress conditions, confirming CaGPX3's key involvement in salt tolerance.