2012 Annual Report 1a.Objectives (from AD-416): Soybean yields are affected quantitatively and qualitatively by fungi, insects, nematodes, and viruses. The ability of pathogens and pests to colonize and/or infect soybean plants is the result of interactions of pathogen and host genes that allow pathogenic organisms to reproduce and cause disease. The objective of this cooperative research project is to identify and characterize the expression of soybean and pathogen genes involved in the establishment and/or maintenance of disease-causing interactions. 1b.Approach (from AD-416): Candidate soybean genes that support/permit pathogen accumulation or that are involved in pathogenesis will be identified through the genetic analysis of soybean lines differing in their susceptibility to pathogens and pests. In addition, genes expressed at the host-pathogen interface will be identified and characterized using genetic and expression profiling techniques. The involvement of the genes in disease will be confirmed by gene-specific complementation and/or gene silencing. Pathogen genes will be identified by similar genetic and expression profiling techniques. Host and pathogen proteins that physically interact in diseased cells will be identified through in vivo interaction studies and in vitro protein binding and affinity chromatography analyses. 3.Progress Report: Six novel RNA viruses were identified infecting isolates of the fungus that causes soybean sudden death syndrome (Fusarium virguliforme) and one virus infecting the fungus that causes Sclerotinia stem rot (Sclerotinia sclerotiorum). Two of the viruses infecting Fusarium virguliforme were associated with significant reductions in the aggressiveness of the virus-infected fungal isolates. Sudden death syndrome and Sclerotinia stem rot are two damaging diseases of soybean for which high levels of resistance have not yet been identified in soybean. Hence, these viruses have the potential to reduce the severity of sudden death syndrome disease symptoms in soybean and could be developed into tools to help mitigate losses caused by the disease. The effects of the other viruses on the virulence of the fungi they infect are being investigated.