Genome-wide identification, characterization and expression analysis of glutaredoxin gene family (Grxs) in Phaseolus vulgaris

Glutaredoxins (Grxs) are ubiquitous oxidoreductase proteins implicated in development and abiotic stress response mainly through maintaining redox homoeostasis. Here, we conducted the first systematic analysis of the Grx gene family (PvGrx) in the most popular legume Phaseolus vulgaris (common bean). A total of 50 PvGrx genes were identified, and divided into four classes (CC-type, CGFS-type, CPYC-type and Grl-type) based on the phylogenetic analysis. The different classes have different introns-exons structures and conserved motifs, indicating functional divergence in the PvGrx family. Both tandem and segmental duplications were found to be involved in the expansion of PvGrx family that underwent a purifying selection by excluding the deleterious loss-of-function mutations. Cis-acting regulatory elements and gene ontology analyses predicted their role of distinctive members in abiotic stress response and hormonal signalling. RNA-seq based expression analysis revealed their differential expression pattern during plant development. On the other hand, RT q-PCR analysis revealed that target PvGrx isoforms were associated with nodule organogenesis and symbiosis based on their expression profiles. In addition, a battery of PvGrx candidates were markedly upregulated by different abiotic stressors suggesting their broad spectrum of functions. These findings serve as a reference for functional analysis and genetic improvement in P. vulgaris and related legume species.