Confirmation of a seed yield QTL in soybean

Exotic germplasm can be an important source of genetic diversity for soybean [Glycine max (L.) Merr.] improvement. Previously, four yield quantitative trait loci (QTL) had been identified in a cross between the exotic soybean plant introduction (PI) 68658 and the U.S. cultivar Lawrence. The confirmation of these QTL in other genetic backgrounds will provide further evidence of their usefulness in cultivar development. To confirm the four yield QTL, a population of 117 recombinant inbred lines (RILs) was developed from a backcross using a line from the initial PI 68658 mapping study as the donor parent and LD00–3309, a high-yielding elite cultivar, as the recurrent parent. The confirmation population was grown in Illinois at two locations in 2008, 2009, and 2010. One yield QTL, linked to marker Satt300 on chromosome (Chr) 5, was confirmed across the experiment (p < 0.01), and the high-yield allele was contributed by exotic parent PI 68658. This QTL was given the confirmed designation cqSeed yield-002. A second yield QTL, linked to Satt474 on Chr 14, was significant (p < 0.05) across the experiment, with the high-yield allele contributed by LD00–3309. Analysis of yield components from one location showed a significant increase in the total number of pods per plant associated with both of these markers. Our results provide evidence that valuable yield QTL exist in exotic soybean germplasm and that these QTL could be used to increase yield in modern cultivars.