The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na
+] and [K
+] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato.
HKT1;1 and
HKT1;2, two tomato Na
+‐selective class I‐HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single‐nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from
HKT1;1 and
HKT1;2. Their expression patterns and phenotypic effects were further investigated in two near‐isogenic lines (NILs): 157‐14 (double homozygote for the
cheesmaniae alleles) and 157‐17 (double homozygote for the
lycopersicum alleles). The expression pattern for the
HKT1;1 and
HKT1;2 alleles was complex, possibly because of differences in their promoter sequences. High salinity had very little effect on root dry and fresh weight and consequently on the plant dry weight of NIL 157‐14 in comparison with 157‐17. A significant difference between NILs was also found for [K
+] and the [Na
+]/[K
+] ratio in leaf and stem but not for [Na
+] arising a disagreement with the corresponding RIL population. Their association with leaf [Na
+] and salt tolerance in tomato is also discussed.
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