Genetic Diversity of Japanese Strawberry Species Based on Microsatellite Markers

The United States Department of Agriculture (USDA) - Agricultural Research Service (ARS) - National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, is a genebank that preserves strawberry genetic resources. The Fragaria L. collection consists of more than 1700 accessions of 17 species from 37 countries. In 2004, Asian diploid species, F. iinumae Makino and F. nipponica Makino, were collected during an expedition to Hokkaido, Japan. An ancestor of F. iinumae may be a progenitor of the "B" genome for octoploid strawberry species. The objective of this study was to evaluate the diversity of these two species using microsatellite markers. We report preliminary results obtained from SSR analysis of 139 accessions based on 20 SSRs. A higher genetic diversity was observed in F. nipponica, which tends to be cross pollinated, than in F. iinumae, which tends to be self-pollinated. This study identified putative hybrids between F. iinumae and F. nipponica as well as an unexpected octoploid accession from Hokkaido, Japan. The hybrid nature of these accessions and the possible source of this octoploid accession will be further evaluated using chloroplast and nuclear markers as well as morphological traits.