Development and Characterization of Microsatellite Markers in Sweetpotato

Abstract

To promote the implementation of genetic analyses and breeding programs, a set of microsatellite markers in sweetpotato should be developed, which cover the entire sweetpotato genome. To achieve this objective, 102 polymorphic microsatellite markers were developed using three different methods: 1) screening of a small-insert genomic library, 2) construction of a microsatellite-enriched library (51-fold enrichment) and 3) mining of EST databases. Approximately 8,000 clones of the small-insert library were screened with (GA)₂₀ and (CA)₂₀ probes, and 42 positive clones were identified. One hundred and twenty-two clones containing microsatellites were identified from the enriched library, which consisted of 800 clones. Thirty-two and 47 primer pairs were designed for these clones containing microsatellites from the small-insert library and enriched library, respectively. Among the sweetpotato accessions examined, 27 of these microsatellite markers showed polymorphism. Eventually, 4,153 sequences from a published expressed sequence tag (EST) databases were mined as a source for the development of microsatellite markers, and 379 sequences containing microsatellites were identified. A total of 151 primer pairs were designed and 120 scorable microsatellite markers were obtained. Seventy-five EST-SSR loci showed length polymorphisms. Of these polymorphic loci, 71 % were associated with some genes.