The reported narrow genetic base of cultivated potato (Solanum tuberosum) can be expanded by the introgression of many related species with large genetic diversity. The analysis of the genetic structure of a potato population is important to broaden the genetic base of breeding programs by the identification of different genetic pools. A panel composed by 231 diverse genotypes was characterized using single nucleotide polymorphism (SNP) markers of the Illumina Infinium Potato SNP Array V2 to identify population structure and assess genetic diversity using discriminant analysis of principal components (DAPC) and pedigree analysis. Results revealed the presence of five clusters within the populations differentiated principally by ploidy, taxonomy, origin and breeding program. The information obtained in this work could be readily used as a guide for parental introduction in new breeding programs that want to maximize variability by combination of contrasting variability sources such as those presented here.

Phytophthora infestans (Mont.) de Baryis found in all areas of potato (Solanum tuberosum L.) production in Argentine. Association mapping uses the existing diversity in a a population to identify loci responsible of phenotypic variation of a character. The studied population was formed by 159 genotypes of the germplasm collection of the Instituto Nacional de Tecnología Agropecuaria (INTA) Estación Experimental Agropecuaria (EEA) Balcarce potato breeding program. These genotypes are part of a larger population that was previously analyzed using single‐nucleotide polymorphism (SNP). Phenotypic assessment was carried out in two locations over 3 yr. Environmental conditions allowed the presence of the disease in all year × location combination. Phenotypic variability was found for relative area under disease progress curve (RAUDPC) and yield parameters as, Total weight and Seed weight. Association mapping was carried out on 159 genotypes. Eight significant associations were found using Bonferroni methodology, with values of −log(p) ranging between 4.61 and 5.42 located at chromosomes 3 (solcap_snp_c2_16679), 4 (solcap_snp_c1_6126 and solcap_snp_c2_38243, solcap_snp_c2_54077), 5 (solcap_snp_c2_42374), 6 (solcap_snp_c2_33228), 7 (solcap_snp_c1_7407), and 10 (solcap_snp_c2_63) and eleven significant associations using permutation tests with values of −log(p) between 4.5 and 6.42 located at chromosomes 1(solcap_snp_c1_5150), 2 (solcap_snp_c1_13923), 4 (solcap_snp_c1_4178, and solcap_snp_c2_50004), 5 (solcap_snp_c2_11829 and solcap_snp_c2_50532), 7 (solcap_snp_c2_35057 and solcap_snp_c1_10011), and 9 (solcap_snp_c2_1915). Some of the SNPs detected are adjacent to genes that encode enzymes that participate in metabolic pathways that are activated in response to interaction with pathogens. Those markers might be included in breeding programs related to improve late blight resistance in potato cultivars.