Genome-Wide Characterization and Expression Analysis of NHX Gene Family under Salinity Stress in and Its Comparison with .

Cotton is an important economic crop affected by different abiotic stresses at different developmental stages. Salinity limits the growth and productivity of crops worldwide. Na/H antiporters play a key role during the plant development and in its tolerance to salt stress. The aim of the present study was a genome-wide characterization and expression pattern analysis under the salinity stress of the sodium-proton antiporter (NHX) of in comparison with . In , 25 genes were identified on the basis of the Na_H exchanger domain. All except one of the transporters have an Amiloride motif that is a known inhibitor of Na ions in plants. A phylogenetic analysis inferred three classes of genes-viz., Vac (, and ), Endo (), and PM (). A high number of the stress-related -acting elements observed in promoters show their role in tolerance against abiotic stresses. The Ka/Ks values show that the majority of genes are subjected to strong purifying selection under the course of evolution. To study the functional divergence of transporters, the real-time gene expression was analyzed under salt stress in the root, stem, and leaf tissues. In , the expression was higher in the stem, while in the leaf and root showed a high expression. Moreover, our results revealed that homologues in both species have a high expression under salinity stress at higher time intervals, followed by . The protein-protein prediction study revealed that is involved in the CBL-CIPK protein interaction pathway. Our study also provided valuable information explaining the molecular mechanism of Na transport for the further functional study of Gossypium genes.