QTL Associated with Yield in Three Backcross-Derived Populations of Soybean

Soybean [Glycine max (L.) Merrill] plant introductions (PIs) are potential sources of useful genes for breeding. We mapped quantitative trait loci (QTL) for yield and other agronomic traits, and determined QTL x environment (QTL x E) and epistatic interactions for yield in three backcross (BC) populations. The populations were developed using PIs as donor parents and 'Beeson 80', 'Kenwood', and 'Lawrence' as recurrent parents (RP). Sixty-eight BC2F5-derived lines in the Beeson 80 population, 74 BC1F5-derived lines in the Kenwood population, and 94 BC3F2-derived lines in the Lawrence population were tested along with the RP and checks in 2003 and 2004. Nineteen QTL for three other agronomic traits were identified, as well as 13 yield QTL. The yield-increasing allele was from the PI parent for eight yield QTL. Yield-increasing alleles were associated with delayed maturity for three yield QTL, and one allele was associated with increased lodging and plant height. All yield QTL mapped to regions where yield QTL have been reported previously. The significant QTL x E interaction was due to undetectable or weak QTL effects in some environments. Nine digenic interactions for yield were detected in the Kenwood population, and were mostly between loci exhibiting epistatic effects only. Our results support previous findings that the current elite North American soybean gene pool is more diverse than would have been predicted by the number of contributing ancestors.