2011 Annual Report 1a.Objectives (from AD-416) 1) Identify new sources of resistance and introgress resistance genes into desirable agronomic backgrounds;. 2)Phenotype mapping populations for developing new DNA markers and confirm resistance. 1b.Approach (from AD-416) Screen soybean germplasm using standardized methods in greenhouse assay. Phenotype mapping populations from other scientists. Evaluate for presence of DNA markers using PCR reactions for Marker assisted selection. 3.Progress Report For broadening the resistance in soybean, additional soybean germplasm is being screened to identify new sources of resistance to soybean cyst nematode (SCN). Genetic mapping populations are also being screened (phenotyped) in the greenhouse to confirm resistance and to develop new DNA markers associated with resistance derived from PI438489B. Soybean PI438489B is a new introduction from China whose resistance to multiple nematode populations was discovered at ARS, Jackson, TN. Since it is not desirable commercially, PI438489B was crossed to the cultivar Hamilton to develop progenies for selecting commercially acceptable lines with nematode resistance. These progenies are used for developing DNA markers tagged to nematode resistance to be followed by release of desirable source material for more durable resistance. The greenhouse screening and development of desirable source materials are in progress, and the data are shared among collaborators. ADODR monitored the research primarily through meetings, site visits, emails and conference calls.