2010 Annual Report 1a.Objectives (from AD-416) The long-term goal of this project is to develop soybean varieties or germplasm that have a high level of resistance to Sclerotinia stem rot. The short-term supporting objectives are: (1) further evaluate the advanced lines selected from a previous project and release the best lines as germplasm or varieties; (2) evaluate seven populations of F4 derived lines with resistance from five new resistant plant introductions (PIs) for resistance to Sclerotinia stem rot and agronomic traits; and (3) determine if reported QTLs associated with resistance to Sclerotinia stem rot are also associated with the resistance in the five new resistance sources. 1b.Approach (from AD-416) For objectives 1 and 2, the lines will be evaluated in multiple locations in Michigan for yield and agronomic traits. The lines will also be evaluated for resistance to Sclerotinia stem rot in the greenhouse with the spray-mycelium method and/or drop-mycelium method developed by us. About 15% of the lines will be selected based on the greenhouse resistance to Sclerotinia stem rot, yield, and other agronomic traits. The selected lines will be evaluated in our disease nursery for resistance to Sclerotinia stem rot and yield under disease pressure. Five to 10 lines will be selected and tested in the Uniform Soybean Tests – Northern Region (19 locations in 10 northern US states and 1 Canadian province), for yield and other agronomic traits. The best 1-3 lines will be released to the public. For objective 3, the same seven populations evaluated for objective 2 will be genotyped with polymorphic SSR (simple sequence repeat) and SNP (single nucleotide polymorphism) DNA markers within 20 cM on either side of 34 reported QTLs for resistance to Sclerotinia stem rot. The DNA marker data and the disease resistance data obtained under objective 2 will be analyzed together to determine if the reported QTLs are also associated with the resistance in the five new resistance sources. 3.Progress Report This project was initiated on June 1, 2009, research is ongoing, and the overall goal of this project is to develop soybean varieties or germplasm that have a high level of resistance to Sclerotinia stem rot. ADODR monitoring activities to evaluate research progress included phone calls, meetings with the cooperator, and an annual meeting held each year in January. Enhancing soybean resistance to Sclerotinia stem rot: Sclerotinia stem rot is an important soybean disease in the northern soybean production states of the U.S. The disease has been estimated to cause a total yield loss of over 192 million bushels from 1996 to 2008. The best way to control this disease is though the use of soybean varieties with partial resistance to the disease. This continuing research is directed toward:. 1)further evaluating the advanced lines selected from a previous project and releasing the best lines as germplasm or varieties;. 2)evaluating seven populations of F4 derived lines with resistance from five new resistant plant introductions (PIs) for resistance to Sclerotinia stem rot and agronomic traits; and,. 3)determining if reported QTLs associated with resistance to Sclerotinia stem rot are also associated with the resistance in the five new resistance sources. Several promising lines are currently being evaluated for agronomic traits in multiple locations and in multiple states. These lines will also be evaluated for level of resistance to Sclerotinia stem rot in the field and in the greenhouse. About 400 new breeding lines, derived from five new resistant sources, will be evaluated for agronomic performance and for resistance to Sclerotinia stem rot. DNA markers linked to QTLs associated with resistance to Sclerotinia stem rot will be used to test the 400 derived lines to determine whether these markers are also associated with the disease resistance in the five new PIs. Results from this research will contribute to the development of soybean varieties or germplasm with high level of resistance to Sclerotinia stem rot.