2011 Annual Report 1a.Objectives (from AD-416) The long-term objective of this work is the discovery of genes or other genetic factors that control soybean yield potential. The specific objective of this research is the creation of large set of recombinant inbred lines (RILs) derived from the cross of the elite soybean genotype IA3023 with a diverse set of cultivars and germplasm accessions and the analysis of the RILs with 1536 single nucleotide polymorphism (SNP) DNA markers. 1b.Approach (from AD-416) A total of 1200 F2 plants from each of 40-50 matings between IA3023 and high yielding elite and exotic soybean lines will be planted in the field. At least 1000 F2 plants from each of those matings with maturity as similar as possible to the common Maturity Group III parent IA3023 will be harvested via single-seed descent (SSD) and the 1000 F3 seed of each mating will be shipped to a winter nursery to initiate a two-generation SSD advance to produce first F4 then F5 seed. The F5 plants will be grown in the field and leaf tissue will be harvested from each F5 plant for DNA extraction. Seed will be harvested from a minimum of 500 F5 plants per mating and increased in a winter nursery to produce sufficient seed of 250 RILs per mating for yield testing in replicated yield trials. Each of the RILs will also be characterized with 1536 SNP DNA markers using the Illumina GoldenGate assay. 3.Progress Report This research is supported with funds from the United Soybean board. In the fall of 2010, seeds of 120 individual plants from each of 20 matings grown in Urbana, IL were harvested. A leaflet was also collected from each of the 140 plants for the purpose of DNA isolation. The harvested seeds were sent to Argentina for seed increase in preparation for yield testing of 70 progeny lines from each mating along with 70 progeny from an additional set of progeny lines from 20 other matings grown at Lincoln, NE. The yield trials with 70 progeny lines from each of the 39 matings (one mating was lost) were successfully planted near Urbana, IL on May 19 and are growing very well. Progress is monitored via quarterly written reports and by frequent phone conferences with the collaborator at the University of Illinois and via e-mail correspondence concerning the progress of the project.