Rice (Oryza sativa L.) has been considered one of the most important crops in Ethiopia. Landraces and improved accessions in Ethiopia were characterized on the basis of polymorphism data for SSR markers, and classified into two groups: I and II. Cluster I was further divided into two sub-clusters, Ia and Ib. Cluster Ia corresponded to Japonica-like type, Cluster Ib to Japonica type, and Cluster II to Indica type with some Indica-like type. Many landraces and improved varieties belonged to Cluster Ia. Superior landraces were included in Cluster Ib. Further categorization based on blast resistance demonstrated three groups: Clusters A, B1, and B2. Cluster A comprised accessions with relatively high resistance, whereas Clusters B1 and B2 included susceptible accessions. Most of the improved varieties were found in Cluster A. Superior landraces, X-Jigna classified into Ib or DNA type tended to be susceptible in Cluster B2 for blast resistance. These results demonstrated that traditional landraces preferred by farmers should be improved for disease resistance using blast-resistant varieties. In order to avoid hybrid sterility occurring in cross-hybridizing breeding between Indica and Japonica types, desirable parental accessions can be chosen within the same DNA cluster. The clustering information among accessions may be useful in breeding schemes for selection of counterparts in cross-breeding programs.

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