Sclerotinia Blight Resistance in the US Peanut Mini-Core Collection

Germplasm collections are valuable sources of desirable traits such as disease resistance, but many accessions have yet to be characterized. Seventy-one accessions of the US peanut (Arachis hypogaea L.) mini-core were evaluated from 2013 to 2015 for yield, seed quality characteristics, Sclerotinia blight (caused by Sclerotinia minor Jagger) resistance in the field, and for a Sclerotinia resistance marker. Twenty-one accessions with < 10% and six accessions with < 5% disease incidence were identified from the 2 yr most favorable for disease. Resistant accessions were more likely to have a simple sequence repeat marker for Sclerotinia blight resistance, and a negative correlation between disease incidence and the presence of the resistance marker was observed. One resistant mini-core accession, CC650 (PI 478819), was similar to commercial cultivars in yield (3617 kg ha(-1) over 3 yr). CC650 also had the highest seed grade among entries at 73%, large kernels (73 g 100 seed(-1)), and a large proportion of extralarge kernels. In growth chamber inoculation tests, CC650 was similar to the resistant cultivar 'Georgia-03L'. These results may be useful to peanut breeders seeking additional sources of resistance to Sclerotinia minor.