QTL Associated with Yield in Three Backcross-Derived Populations of Soybean-Crop Science-2007-Guzman.pdf

QTL Associated with Yield in Three Backcross-Derived Populations of Soybean P. S. Guzman,* B. W. Diers, D. J. Neece, S. K. St. Martin, A. R. LeRoy, C. R. Grau, T. J. Hughes, and R. L. Nelson ABSTRACT Soybean [Glycine max (L.) Merrill] plant introductions (PIs) are potential sources of useful genes for breeding. We mapped quantita- tive trait loci (QTL) for yield and other agronomic traits, and deter- mined QTL 3 environment (QTL 3 E) and epistatic interactions for yield in three backcross (BC) populations. The populations were developed using PIs as donor parents and FBeeson 80_, FKenwood_, and FLawrence_ 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 asso- ciated with increased lodging and plant height. All yield QTL mapped to regions where yield QTL have been reported previously. The significant QTL3E 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 contribut- ing ancestors. THE AVERAGE rate of yield increase of soybean in theUSA is estimated at 0.023 Mg ha21 yr21 (Orf et al., 2004). A factor that may be impeding the rate of yield improvement of U.S. soybean is the narrow genetic base of the crop in North America (Gizlice et al., 1994; Sneller, 1994; Sneller et al., 1997; Thompson et