Genetic Diversity and Relationships Assessed by SSRs in the USDA World-Wide Rice Germplasm Collection.

Understanding a germplasm collection is essential for mining special genes and further development of the collection. The USDA rice (Oryza sativa L.) collection contains about 20,000 accessions from 116 countries. This diverse in origins indicates a variety of different edaphic and climatic environments for these genotypes to adapt. These ecotypes can be differentiated using SSR markers, and the resulting dendrograms can be used to reconstruct the similarities between genotypes, and patterns of introduction and spread of rice varieties around the world. A core collection with 1,970 entries is proved to be representative of the collection, so it has been genotyped with 50 SSR markers. The genetic diversity and relationship among world-wide rice accessions were assessed. Information on the diversity could be used to identify genetic gap for collection development and the relationship could be used to fill the gap with germplasm from certain area instead of a specific country, depending on diplomatic circumstances.