Abstract

Rice is sensitive to salt stress, but its sensitivity varies among genotypes, indicating natural variation in regulatory mechanisms and genetic makeup. High-affinity potassium transporters (HKTs) that transport cations across membranes play important roles in stress responses of plants. In this study, the gene sequence polymorphisms and expression level of OsHKT1;3 which is a member of the rice HKT gene family was assessed. Sequence analysis indicated 5 single nucleotide polymorphisms (SNPs) in the coding sequence; 4 nucleotide substitutions, one nucleotide deletion and one nucleotide insertion in the promoter region of OsHKT1;3 gene. Among 5 SNPs in the coding sequence, one was non-synonymous (C598G) which caused the change in amino acid L200V and 4 were synonymous substitutions (A798C, G2083A, T2101C, C2122T). The substituted amino acid L200V was predicted to locate in the third transmembrane segment of OsHKT1;3 protein. In the promoter region, 3 nucleotide substitutions at position -879, -453, and -202 caused the change in cis-elements with 8 deletions and 3 additions. Expression levels of OsHKT1;3 were analyzed in the leaves and the roots under 2 different salt concentrations and showed a tendency of reduction in most of the conditions.

Keywords: OsHKT1;3, salt stress, rice, polymorphism.