2007 Annual Report 1a.Objectives (from AD-416) Search for and identify resistance sources of grain legumes to white mold caused by Sclerotinia sclerotiorum by screening the commercial cultivars and core germplasm collections of peas, chickpeas, and lentils. Develop efficient field and greenhouse screening technique suitable for each of the grain legume crops. Determine the genetic nature of the identified resistance and potentially related genes by using traditional and modern genetic techniques including hybridization and progeny analysis, gene cloning and disruption. Investigate genetic variability of the pathogen. Formulate an approach to incorporate the resistance into future cultivars of peas, chickpea, and lentils for efficient management of white mold in grain legume production. Publish findings in international journals. 1b.Approach (from AD-416) Compare various techniques for inoculum production and inoculation onto peas, chickpea, and lentils. Select the best technique to screen the commercial cultivars and core germplasm collections of the grain legumes. Evaluate plant growth habit in relation to white mold resistance. Use traditional genetic techniques such as hybridization to determine the inheritance pattern of the identified resistance. Employ modern genetic techniques to locate resistance genes in grain legumes, and to isolate and disrupt the pathogenicity gene in the pathogen. Utilize vegetative compatibility grouping technique and DNA fingerprinting to determine genetic variability of S. clerotiorum. Document the SCA with the Department of Plant Pathology at Washington State University, Pullman. Formerly 5348-21000-007-02S (August 2003). 3.Progress Report This is a specific cooperative agreement between ARS and Washington State University, Department of Plant Pathology. Additional details of research can be found in the report for the parent CRIS 5348-21000-014-00D, Germplasm Enhancement, Genetics and Disease Management of Cool Season Food Legumes. Research efforts of this research agreement were on developing techniques to unequivocally determine the species identities of Sclerotinia isolates obtained from chickpea, and demonstrate their pathogenicity on chickpea plants. The identities of Sclerotinia isolates obtained from chickpea (Cicer arietinum L.) plants showing stem and crown rot were determined using cultural characteristics, ascospore morphology, variations in group I introns and ITS sequences. Isolates could be separated into two groups based on growth rates, fast growing vs. slow growing. Growth on a pH-indicating medium showed that all fast growing isolates produced abundant acid and all slow growing isolate did not. The slow growing isolates contained at least one group I intron in the nuclear 18s subunit rDNA, whereas all fast growing isolates lacked group I introns in the same DNA region. ITS sequences of the slow growing isolates were identical to previously deposited sequences of Sclerotinia trifoliorum. ITS sequences of the fast growing isolates were identical to deposited sequences of S. sclerotiorum. A technique was developed to induce carpogenic germination of sclerotia of Sclertoinia isolates, which allowed direct observation of ascospore morphology. The slow growing isolates showed ascospore dimorphism, a definitive character of S. trifoliorum, whereas the fast growing isolates showed no ascospore dimorphism. Isolates of both the slow growing and the fast growing are pathogenic on chickpea and caused symptoms similar to those observed in the field. This research showed for the first time in North America that S. trifoliorum causes stem and crown rot of chickpea. Research progress is monitored via weekly informal discussions, monthly progress and planning meetings, and regular visits to the collaborator's greenhouse facility where disease screening is conducted, which located at WSU-IAREC, Prosser, WA