Identification, structural characterization and phylogenetic analysis of Na +/H + antiporter (NHX) genes across the fava bean's (Vicia faba L.) genome

Plant Na +/H + antiporter (NHX) genes enhance salt tolerance by sequestering Na+ into vacuoles or effluxing it across the plasma membrane. This study aimed to identify and characterize NHX genes in fava bean. Seven VfNHX genes were explored and named as VfNHX1-VfNHX7 on the basis of their order in the phylogenetic tree. The protein length, isoelectric points and GRAVY of all 7 proteins ranged from 529-1155, 5.2-8.9 and 0.142-0.637, respectively. The vacuole was predicted as a major residence for all 7 NHX proteins. Amiloride was conserved in the third motif of all members except VfNHX7. Exons′ number in VfNHX genes ranged from 14-23. Segmental duplication contributed 28.5% to the VfNHX gene family expansion. Ka/Ks ratio of paralogs revealed that they were all under purifying selection. Salt-associated cis-acting elements, including GT1-motif, TGACG-motif, ABRE, G-box, MBS, and TGA, were detected in VfNHX promoters. This study provides a base for functional validation of VfNHX genes and their contribution towards salt tolerance.