Abstract
DNA fingerprinting is a powerful tool for plant diversity studies, cultivar identification, and germplasm conservation and management. In breeding programs, fingerprinting and diversity analysis provide an insight into the extent of genetic variability available in the breeding material, which in turn helps breeders to maintain a pool of highly diverse genotypes by avoiding the selection of closely related parents. Oblong-long tubers with russeting skin characterize Russet potato, a primary potato market class in the United States, and especially in the western production regions. The aim of this study was to estimate the level of genetic diversity within this market class potato, utilizing clones and varieties from various breeding programs across the United States. A collection of 264 Russet and non-Russet breeding clones and varieties was fingerprinted using 23 highly polymorphic genome-wide simple sequence repeat (SSR) markers, resulting in 142 polymorphic alleles. The number of alleles produced per SSR varied from 2 to 10, with an average of 6.2 alleles per marker. The polymorphic information content and expected heterozygosity of SSRs ranged from 0.37 to 0.89 and 0.50 to 0.89 with an average of 0.77 and 0.81, respectively. Out of these 23 markers, we propose nine SSR markers best suited for fingerprinting Russet potatoes based on polymorphic information content, heterozygosity and ease of scoring. Diversity analysis of these clones suggest that there is significant diversity across the breeding material and the diversity has been evenly distributed among all the regional breeding programs.