Novel Class of Simple PCR Markers with SNP-Level Sensitivity for Mapping and Haplotype Characterization in Solanum Species

The RB gene from wild potato Solanum bulbocastanum imparts broad-spectrum late blight resistance to cultivated potato. To explore marker associations and haplotype frequencies near RB, we developed, optimized, validated, and employed a set of markers specific to the haplotype associated with the RB resistance allele. Our markers, developed using a mismatch amplification mutation assay (MAMA)-PCR approach, have single nucleotide polymorphism-level sensitivity. MAMA markers were validated via linkage mapping and applied to a collection of 60 S. bulbocastanum genotypes representing the geographic distribution of the species. Considerable marker disassociation within a 100 kb region encompassing RB was revealed. Physical distance between markers was not an effective predictor of marker disassociation. Applied to a collection of four S. bulbocastanum genotypes of known RB allelic status, a set of six MAMA markers accurately predicted the presence of the RB allele. Implications for marker aided genotype selection and association mapping in wild potato species are explored.