Exclusion of sodium ions from cells is one of the key salinity tolerance mechanisms in plants. The high-affinity cation transporter (
HKT1;
5) is located in the plasma membrane of the xylem, excluding Na
+ from the parenchyma cells to reduce Na
+ concentration. The regulatory mechanism and exact functions of
HKT genes from different genotypic backgrounds are relatively obscure. In this study, the expression patterns of
HKT1;
5 in A and D genomes of wheat were investigated in root and leaf tissues of wild and domesticated genotypes using real-time PCR. In parallel, the K
+/Na
+ ratio was measured in salt-tolerant and salt-sensitive cultivars. Promoter analysis were applied to shed light on underlying regulatory mechanism of the
HKT1;
5 expression. Gene isolation and qPCR confirmed the expression of
HKT1;
5 in the
A and
D genomes of wheat ancestors (
Triticum boeoticum, AbAb and
Aegilops crassa, MMDD, respectively). Interestingly, earlier expression of
HKT1;
5 was detected in leaves compared with roots in response to salt stress. In addition, the salt-tolerant genotypes expressed
HKT1;
5 before salt-sensitive genotypes. Our results suggest that
HKT1;
5 expression follows a tissue- and genotype-specific pattern. The highest level of
HKT1;
5 expression was observed in the leaves of
Aegilops, 6 h after being subjected to high salt stress (200 mM). Overall, the D genome allele (
HKT1;
5-D) showed higher expression than the A genome (
HKT1;
5-A) allele when subjected to a high NaCl level. We suggest that the D genome is more effective regarding Na
+ exclusion. Furthermore,
in silico promoter analysis showed that
TaHKT1;
5 genes harbor jasmonic acid response elements.
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