Genome-wide identification of HKT gene family in wheat (Triticum aestivum L.): Insights from the expression of multiple genes (HKT, SOS, TVP and NHX) under salt stress

Potassium (K+) transporters, particularly high-affinity K+ transporters (HKT), are crucial for plant growth and abiotic stress response. These transporters regulate Na+ and K+ balance in the cells to prevent sodium toxicity in plant tissues. Although HKT genes have been extensively studied in various crops, there is a deficiency in their characterization and understanding of their role in wheat, particularly regarding their involvement in adaptive response to environmental stresses like salinity. In this study, several bioinformatics tools including web-based platforms and software applications were employed to identify, characterize and localize HKTs genes within the wheat genome. A greenhouse trial was also conducted to investigate the mRNA expression levels of some of the significant salt-responsive genes in wheat seedlings grown under different concentrations of NaCl (0, 200, and 400 mM). Genome-wide analysis, resulted in identification of 35 TaHKTs that are unevenly distributed on ten chromosomes. The majority of these transporters are localized on plasma membrane. Analysis of promoter regions showed that most of the TaHKT genes have abundant cis-elements that involved in hormones and abiotic stress responses. Gene expression analysis indicated a significant upregulation of TaHKT6 and TaSOS1 genes were found in wheat seedlings treated with 400 mM NaCl. Expression levels of TaNHX1, TaNHX2 and TaTVP1 genes were also higher in 200 mM and 400 mM NaCl-treated plants when compared to non-stressed plants. Overall, the results provide further evidence for the role of the TaHKT in wheat's stress response to elevated salt levels and pave the way for further functional research in K+ transporters in plants.