Na+/H+ antiporter (NHX) and salt stress tolerance

Soil salinity is known to be a major problem for agricultural practices, worldwide. Furthermore, the situation is deteriorating with the increase in vagaries in the climate and increasing soil salinization. Scientists across the globe are in a race to find a suitable answer to the threat of soil salinity. One such effort includes the exploration of Na+/H+ transporter (NHX) genes in various plant species. NHX genes are Na+/H+ transporters belonging to the family of cation-proton antiporters 1. NHXs play pivotal roles in the homeostasis of Na+ and K+. They are important for plant growth and development. NHXs are divided into three broad groups on the basis of their localization, that is, vacuolar, endosomal, and plasma-membrane localized NHX proteins. A number of NHX genes have been identified and studied by different research groups. Studies suggest the presence of around 10–12 transmembrane regions in NHXs. Evolutionary analyses performed for the different plant species suggests the phylogenetic conserveness among the NHX proteins. Furthermore, other structural and characteristic features of NHX protein family also indicate the conserved nature of NHXs. Here in this chapter, we have discussed the structural and evolutionary features of NHXs of different plants. The transgenic approaches for the formation of salt-tolerant plants have also been discussed.