Genotyping of the Valencia Peanut Core Collection with a Molecular Marker Associated with Sclerotinia blight Resistance

Cultivated peanut, the second most economically important legume crop throughout the United States and the third most important oilseed in the world, is consistently threatened by various diseases and pests. Sclerotinia blight, (causal agents Sclerotinia sclerotiorum (S. sclerotiorum) and Sclerotinia minor Jagger (S. minor))is a major threat to peanut production in the Southwestern U.S., Virginia, and North Carolina and can reduce yield by up to 50% in severely infested fields. S. sclerotiorum has now been reported in areas of eastern New Mexico and west Texas where all U.S. grown Valencia peanuts are produced, commonly in organic cropping environments. Host plant resistance provides the most effective solution to managing Sclerotinia blight, especially in organic systems where pesticide use is not an option for disease control. To date, no Valencia cultivars with Sclerotinia blight resistance have been released. In this study, the Valencia peanut core germplasm collection was genotyped with a Simple Sequence Repeat (SSR) marker associated with Sclerotinia blight resistance in order to identify potential germplasm for use in breeding to develop Valencia peanut cultivars resistant to the disease. Thirty accessions from the Valencia peanut core collection have profiles consistent with other genotypes that exhibit less that 5% incidence of Sclerotinia blight under heavy disease pressure. The identified accessions, after field evaluation, may serve as potential sources of Sclerotinia blight resistance in Valencia peanut breeding programs.