[Genetic analysis and gene mapping for a salt tolerant mutant at seedling stage in rice]

A salt tolerant mutant at seedling stage was obtained from an M2 population of radiation mutagenesis of an indica rice cultivar R401. The mutant seedlings could survive under the treatment of sodium chloride solution at the concentration of 150 mmol/L, while the wild-type control seedlings withered and died. An F2 population was developed from a cross between a japonica cultivar Nipponbare and the salt tolerant mutant. By investigating the performance of the F2 population under the stress of 150 mmol/L NaCl solution, we found that the mutant phenotype was caused by the recessive mutation of a single gene, temporarily designated SST(t). Bulked segregant analysis (BSA) based on the F2 mapping population revealed that SST(t) is located on chromosome 6. By analyzing 137 typical salt-tolerant F2 plants using molecular markers, SST(t) was mapped in a 2.3 cM (or 406 kb) interval between InDel markers ID26847 and ID27253, with genetic distances of 1.2 cM and 1.1 cM to the two markers, respectively.