OsHKT1;3 gene sequence polymorphisms and expression profile in rice (Oryza sativa L.)

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 (C598 G) 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.