Identification of Possible New Sources of Sclerotinia Blight Resistance in the U.S. Peanut Mini Core Collection Using a Molecular Marker Associated with Resistance to Sclerotinia minor Jagger.

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 minor Jagger (S. minor), the causal agent of Sclerotinia blight, 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.   Although host plant resistance would provide the most effective solution to managing Sclerotinia blight, limited sources of resistance to the disease are available for use in breeding programs.  Peanut germplasm collections are available for exploration and identification of new sources of resistance, but traditionally the process is lengthy, requiring years of field testing before those potential sources can be identified. Molecular markers associated with phenotypic traits can speed up the screening of germplasm accessions, but until recently none were available for Sclerotinia blight resistance in peanut.  This study objective of this study was to characterize the US peanut mini-core collection with regards to a recently discovered molecular marker associated with Sclerotinia blight resistance.   Ninety-six accessions from the collection were available and genotyped using the SSR marker and 39 total accessions from spanish, valencia, runner market types were identified as potential new sources of resistance and targeted for further evaluation in field tests for Sclerotinia blight resistance.