Phylogeny of the Plant Salinity Tolerance Related HKT Genes

Success in the extension of crop production in the salt affected area may help to meet the demand of the world’s hunger. In plants, Na+ permeable HKT (High-affinity K+ Transporter) gene family represents a primary mechanism for mediating salt tolerance. Better understanding of the relationship among HKT genes may provide a framework for the development of salt tolerance cultivars. In this study, phylogeny of plant-HKT gene family using the available nucleotide sequences in the current databases was examined. This study showed a total of 6 phylo-groups. Phylogenetic analyses based on HKT gene sequences demonstrated distinct lineages for monocots and eudicots. Group I, II and VI contained only monocots. Eudicots were clustered in group III, IV and V. A stable relationship was observed among the members of the group I (previously described as subfamily 2). Overall pairwise mean distance was very high (1.13), indicating the high level of diversity of the HKT gene family. Observed pairwise distances were: Group 4 (eudicots, 0.81) > group 6 (monocots, 0.52) > group 2 (monocots, 0.35) > group 1 (monocots, 0.33) ? group 5 (eudicots, 0.33) > group 3 (eudicots, 0.17).