Identification and characterization of NHX gene family for their role under salt stress in Vigna mungo

• Published in: Physiologia plantarum Vol. 176; no. 5; p. e14563
• Main Authors: Kumar, Kuldeep, Jha, Sudhir Kumar, Kumar, Vaibhav, Sagar, Pritee, Tripathi, Sandhya, Rathore, Meenal, Singh, Awnindra Kumar, Soren, Khela Ram, Dixit, Girish Prasad
• Format: Journal Article
• Language: English
• Published: Denmark 01.09.2024
• Subjects: Gene Expression Regulation, Plant; Multigene Family; Phylogeny; Plant Proteins - genetics; Plant Proteins - metabolism; Salt Stress - genetics; Sodium-Hydrogen Exchangers - genetics; Sodium-Hydrogen Exchangers - metabolism; Vigna - genetics; Vigna - metabolism; Vigna - physiology
• ISSN: 0031-9317; 1399-3054; 1399-3054
• DOI: 10.1111/ppl.14563

In the current study, we have performed a comprehensive analysis of the Sodium Hydrogen Exchanger (NHX) gene family in Vigna mungo, and a total of 44 NHX genes were identified. A bimodal distribution based on domains, gene structure and phylogenetic analysis was evident. All intronpoor and intron-rich genes were clustered in clades I and II, respectively. Interestingly, all genes of subclade IIb were localized to vacuoles and possess only the NHX domain. The isoelectric point and trans-membrane domain analysis reflect the wide distribution of the NHX genes. Interestingly, Vm_NHX2 and Vm_NHX3 lacked trans-membrane domain but were found to interact with other NHX genes as well as vital salinity pathway genes, including calcium-mediated salt-responsive genes. The comparison of the mRNA sequences with that of V. marina, a halophytic species, reflects their independent evolution, majorly supporting the convergent evolution. The Ka/Ks ratio reflects the abundance of purifying selection supporting their conserved function during evolution. In our analysis, several abiotic stress and hormone-responsive elements and transcription factor binding sites were present in the promoter of the NHX genes. Further, the ion partitioning of a tolerant (K90) and a susceptible (K49) variety of V. mungo suggested that K90 managed the Na /K ratio more affluently, which was also supported by profiling of superoxide radicals, hydrogen peroxide, phenol, peroxidase activity and superoxide dismutase activity. From the expression, we identified five candidate Vm_NHX genes, four of which, i.e. Vm_NHX16, Vm_NHX17, Vm_NHX29 and Vm_NHX33, were localized to the vacuolar and lysosomal membrane.