Molecular Analysis of Potatoes from the Pacific Northwest Tri-State Variety Development Program and Selection of Markers for Practical DNA Fingerprinting Applications

DNA fingerprinting is a valuable tool for plant cultivar discrimination and identification. Simple Sequence Repeat (SSR) markers represent an excellent option for obtaining DNA fingerprints of potatoes in an easy, fast, and reliable fashion. The highly polymorphic and co-dominant nature of SSRs gives them good discrimination power to declare the distinctiveness of new potato clones for Plant Variety Protection (PVP) and to properly identify existing cultivars. They are also useful for confirming origin and avoiding duplications and mixtures in breeding, foundation and certification programs, and also during growing and marketing stages. A total of 54 (50 tetraploid and 4 diploid) potato clones, including new cultivars released by the Pacific Northwest Tri-State Potato Variety Development Program and a set of common commercial cultivars, were analyzed using 25 SSR markers. Marketing classes (French fry processing, fresh market, and chip processing) were clearly separated using those markers. We have empirically selected a subset of six SSRs that differentiate all the potato varieties and clones present in the study. This subset of six SSR markers could be used for practical DNA fingerprinting. In order to declare distinctiveness, we recommend that common reference varieties always be genotyped together with the newly tested potato clones and that focus be placed on the relative allelic differences between the new clones and the reference varieties.