|St. Martin, S|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2006
Publication Date: 1/15/2007
Citation: Guzman, P.S., Diers, B.W., St. Martin, S.K., Leroy, A.R., Grau, C.R., Hughes, T.J., Nelson, R.L. 2007. QTL for yield in three backcross-derived populations of soybean. Crop Science. 47: 111-122. Interpretive Summary: The genetic base of commercial soybean production in the U.S. is very narrow and less than 1% of the lines that exist in USDA Soybean Germplasm Collection has been used in soybean breeding. Using exotic germplasm to increase yield has been very difficult because this germplasm has so many attributes that negatively affect agronomic performance. In an effort to identify the positive traits in exotic germplasm, we used the backcross breeding procedure to create high yielding experimental lines that had only 6 to 25% of their genes from exotic germplasm. Using sets of these lines and DNA markers, we were able to identify 8 chromosomal regions contributed by exotic germplasm that were associated with increased seed yield. All eight of these regions have been previously reported as being associated with high yield in other published research; and in these other studies, five of the eight regions had high yield associated with the chromosomal segments originating from US varieties. We have identified three chromosomal regions from exotic germplasm that could useful for increasing yield in US varieties. This information will be useful to soybean breeders and geneticists.
Technical Abstract: 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, 74 BC1F5-derived lines in the Kenwood and 94 BC3F2-derived lines in the Lawrence populations were tested along with the RP and checks in 2003 and 2004. A total of 13 yield and 19 QTL for three agronomic traits were identified. The yield increasing allele was from the PI parent for eight yield QTL. The yield increasing allele was associated with delayed maturity for three yield QTL and one 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 no or weak QTL effects in some environments. Nine digenic interactions for yield were detected in the Kenwood population, which were mostly between loci exhibiting epistatic effects only. Our results support previous findings that the current commercially used soybean gene pool is more diverse than would have been predicted by the number of contributing ancestors.