Identification and validation of a major QTL for salt tolerance in soybean

To identify quantitative trait loci (QTLs) conditioning salt tolerance in soybean (Glycine max (L.) Merr.), two recombinant inbred line (RIL) populations derived from crosses of FT-Abyara x C01 and Jin dou No. 6 x 0197 were used in this study. The FT-Abyara x C01 population consisted of 96 F-7 RILs, and the Jin dou No. 6 x 0197 population included 81 F-6 RILs. The salt tolerant parents FT-Abyara and Jin dou No. 6 were originally from Brazil and China, respectively. The QTL analysis identified a major salt-tolerant QTL in molecular linkage group N, which accounted for 44.0 and 47.1% of the total variation for salt tolerance, in the two populations. In the FT-Abyara x C01 population, three RILs were found to be heterozygous around the detected QTL region. By selfing the three residual heterozygous lines, three sets of near isogenic lines (NILs) for salt tolerance were developed. An evaluation of salt tolerance of the NILs revealed that all the lines with FT-Abyara chromosome segment at the QTL region showed significantly higher salt tolerance than the lines without the FT-Abyara chromosome segment. Results of the NILs validated the salt tolerance QTL detected in the RIL populations.