Genetic variation in blast resistance in rice germplasm from West Africa

摘要

The genetic variation in resistance to blast ( Pyricularia oryzae Cavara) in 195 rice accessions comprising 3 species of the AA genome complex (Asian rice [ Oryza sativa L.], African rice [ Oryza glaberrima Steud.] and wild rice [ Oryza barthii ]) was investigated based on their patterns of reaction to standard differential blast isolates (SDBIs) and SSR marker polymorphism data. Cluster analysis of the polymorphism data of 61 SSR markers identified 3 major clusters: cluster A (mainly Japonica Group or upland accessions), cluster B (mainly Indica Group or lowland accessions) and cluster C ( O. glaberrima and O. barthii ). The accessions were classified again into 3 resistance groups based on reactions to SDBIs: group Ia (susceptible), group Ib (middle resistance) and group II (high resistance). Group Ia included only a few differential varieties, susceptible controls and the Japonica Group cultivar Nipponbare. Accessions in clusters A and B included all 3 resistance groups and showed a wide variation in blast resistance, but cluster C contained only group Ib. These results demonstrated that variations in Asian rice ( O. sativa ) accessions in West Africa were skewed toward high resistance and that variations in O. glaberrima and O. barthii were limited and lower than the Asian rice accessions.