Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2006
Publication Date: 11/15/2006
Citation: Andrade, D., Ghislain, M., Rodriquez, F., Spooner, D.M. 2006. Core collection analysis of the cultivated potato solanum tuberosum phureja group using RAPDS and nuclear SSRS. Theoretical and Applied Genetics. 113:1515-1527. Interpretive Summary: This study is designed to test the use of a type of a DNA technique, termed microsatellites, to help logically group a group of cultivated potatoes called the Phureja Group. The potato cultivars are popularly grown throughout the Andes mountains and are useful to help breed more modern cultivated potatoes grown worldwide. The Phureja group has traditionally been defined to include Andean potatoes that grow best in the short day lengths of the Andes Mountains, that are diploid (have 24 chromosomes), and that have tubers that sprout quickly, rather than lying dormant during storage as most modern potatoes. The results from this microsatellite study show that they can be used to indirectly determine if potatoes are diploid. Microsatellites also group these potatoes differently than a separate type of molecular technique called RAPDs, and they fail to group potatoes that grow near each other any better than potatoes growing far apart from each other. These results highlight both the use and limitations of microsatellites to group these potatoes.
Technical Abstract: The Solanum tuberosum Phureja Group are popular potato landraces widely grown throughout the Andes from western Venezuela to central Bolivia, and form important breeding stock for modern varieties. They have been distinguished by short-day adaptation, diploid ploidy (2n = 2x = 24), and lack of tuber dormancy. This nuclear simple sequence repeat (nuclear simple sequence repeats, or microsatellite) study compliments a prior RAPD study to explore the use of these markers to form a core collection of the Phureja Group. A prior RAPD study analyzed all 128 accessions of the Phureja Group at the International Potato Center, and these formed the initial germplasm for this study. The microsatellite data uncovered 25 unexpected triploid and tetraploid accessions. Twenty-six of the remaining 103 accessions were invariant for microsatellites. Chromosome counts of these 103 accessions highlighted seven more triploids or tetraploids. The microsatellite and RAPD results were highly discordant for the remaining 70 variable diploid accessions. Our results: 1) show the utility of microsatellites to effectively uncover many ploidy variants in cultivated potato, 2) support the use of a cultivar-group (rather than a species) classification of cultivated potato, 3) fail to support a relationship between genetic distance and geographic distance, 4) provide further evidence for the general discordance of RAPD and microsatellite data, 5) question the use of any one molecular marker to construct core collections.