Genome-wide analysis of Heavy metal ATPase (P1B-type ATPase) gene family in Mung bean and their expression analysis under heavy metal (Zn, Cd and Cu) stress

Heavy metal ATPases (HMAs) are important group of transmembrane proteins involved in homeostasis of metal ions in plant systems. In this study, a comprehensive analysis of genome assembly (VC1973A v7.1) resulted in the identification of nine HMA genes (VrHMA) and their corresponding proteins in Mungbean, an agronomically important legume crop known for its nutritional values. VrHMA proteins were also characterized based on their biomolecular features, conserved domains and motifs arrangement, transmembrane helices, pore-line helices, subcellular location and occurrence of signal peptides. Based on sequence homology, nine VrHMAs were clustered into two major substrate-specific groups: VrHMA1, VrHMA5 and VrHMA7 were categorized under the Zn/Co/Cd/Pb ATPase group, whereas the remaining six VrHMAs belong to the Cu/Ag subgroup. Gene structure analysis and promoter scanning revealed the structural divergence and presence of various stress-responsive cis-acting elements, respectively. The expression analysis of VrHMA genes in root and leaf tissues, in response to heavy metal (Zn, Cd and Cu) stress, indicates their role in the uptake, transport and sequestration of metal ions. Interestingly, VrHMA5 showed incremental upregulation in roots in response to all three heavy metal stresses, whereas its expression was only upregulated in the leaf tissues under Zn stress, which indicates its role in vascular transport in V. radiata. In addition, this study provides valuable insights into the functional roles of VrHMA genes and will lay a foundation for future genetic improvement in mung bean aimed at enhanced heavy metal stress tolerance and micronutrient homeostasis.