Quantitative Trait Loci for Resistance to Common Scab and Cold-Induced Sweetening in Diploid Potato.

The development of germplasm with resistance to common scab and cold-induced sweetening is a high priority for the potato ( L.) industry. A mapping population was developed from mating two individuals of a diploid family generated by crossing the susceptible cultivated potato clone US-W4 to the highly resistant wild relative ( Bitter) clone '524-8'. Progeny were evaluated in replicated field trials. Tubers were scored for percentage of surface area with scab lesions, scab lesion type, cold-induced sweetening, average tuber weight, and dry matter. Plants were evaluated for vine maturity. A genetic map was constructed, quantitative trait loci (QTLs) were identified, and the gene action of significant QTLs was characterized using 1606 single nucleotide polymorphisms (SNPs). Significant QTLs for common scab percentage of surface area covered with lesions and lesion type were identified in overlapping regions on chromosome 11 ( = 21.0 and 18.2%, respectively). Quantitative trait loci were identified on chromosomes 4 ( = 17.1%) and 6 ( = 19.4%) for cold-induced sweetening, chromosome 5 for maturity ( = 29.8%), and chromosome 1 ( = 26.3 and 22.0%) for average tuber weight. Identification of QTLs is the first step toward developing molecular markers for breeders to efficiently integrate these desirable traits into cultivars.