Insilico-based genome-wide identification and structural characterization of heat shock proteins 70 (HSP70) in cowpea (Vigna unguiculata L.)

Heat shock protein 70 is conserved a family of ubiquitously expressed proteins that help plants to withstand the major abiotic stresses. Although HSP70 genes have been investigated in a variety of plant species, yet, remain unexplored in cowpea. In the current study, 30 VuHSP70 genes were identified in cowpea genome and characterized for their physiochemical parameters. Super-family “HSP70” domain was found in all VuHSP70 genes. Signals for localization VuHSP70 proteins were detected mostly in cytoplasm. One hundred and twenty HSP70 genes, identified across diverse plant species, were divided into 6 groups. The duplication and speciation events contributed 13% and 47%, respectively, to the extension of HSP70 gene family. The VuHSP70 genes were mapped unequally on nine different chromosomes. Tandem and segmental duplication were recorded in each of the two VuHSP70 paralog gene pairs. Phylogeny based analysis divided VuHSP70 family into six groups. With the exception of group-I, all VuHSP70 genes associated with the same group showed similarities in motifs and gene structure while those belong to different groups exhibited differences. Cis-elements mainly associated with salinity, drought and heat stress were detected in promoter region of VuHSP70 gene. The Ka/Ks ratio of VuHSP70 paralog pairs explored purifying selection as the driven force for evolution of duplicated genes. VuHSP70 genes belong to Group-I and Group-II showed highest expression in all the evaluated tissues. Collectively, the current study is a good addition for further characterization of VuHSP70 genes and exploring the molecular mechanism associated with stress tolerance in cow pea.