Genome-Wide Association Study of Resistance to Potato Common Scab

Potato common scab caused by bacterial pathogen Streptomyces scabies (Thaxt.) Waksman & Henrici is one of the most important diseases of potato ( Solanum tuberosum L.) worldwide. Currently, the most effective and desirable method to control common scab is through the use of resistant cultivars. In order to decipher the genetic control of resistance to common scab disease in Canadian potato germplasm, an association panel of 143 clones including advanced breeding clones and commercial cultivars was genotyped with 12K SolCAP SNPs and phenotyped for potato common scab resistances in multiple years. By conducting a genome-wide association analysis (GWAS) using GWASpoly R package, three resistance QTLs were identified on potato chromosomes 2, 4, and 12, respectively. The phenotypic variation explained by these QTLs was 21%, 19%, and 26%, respectively. The QTL on chromosome 2 was simplex-dominant whereas duplex-dominant QTLs were identified on chromosomes 4 and 12. These findings will be useful to design marker-assisted selection and breeding strategies to improve resistance to common scab in new potato cultivars.