Association of Genome-Wide SNP Markers with Resistance to Common Scab of Potato

Common scab is a soilborne disease that occurs in potato worldwide. Scab is usually present superficially on potato tubers but nonetheless reduces marketability. A genome-wide association study for common scab resistance was performed using 13,002 genome-wide SNPs, with 165 genotypes mostly for chip-processing. We identified a novel QTL for common scab resistance that explained at most 14.7% of the total variance; this QTL was within the 640 kb interval between 0.43 Mb and 1.07 Mb on potato chromosome 1. Recessive homozygosity at this QTL increased levels of resistance. There is no agreement in terms of the locations of QTLs and their genetic modes between the results of previous studies and the present study or among any study. As such, common scab resistance is a highly complex trait, as the QTLs discovered to date are all minor-effect QTLs.