Classification of cultivated rices into indica and japonica types by the isozyme, RFLP and two milled-rice methods

Four methods for classifying cultivated rices (Oryza sativa L.) (including IR varieties) into indica and japonica types - waxy gene product in endosperm starch, glutelin α3 molecular weight in milled rice, RFLP polymorphism at the Wx locus and Glaszmann's isozyme method - were compared. On the basis of the two endosperm traits and the RFLP method Glaszmann's group 1 (indica) was classified as mainly indica and intermediate groups 2, 3 and 4 as exclusively indica. However, the endosperm traits classified Glaszmann's group 5 as mainly indica, while the RFLP method classified it as japonica. The RFLP waxy gene probe was closest to the isozyme method in classifying group 6 as japonicas; the waxy gene product gave mainly indica reaction even in group 6, and the glutelin α3 method was intermediate. All IR rices were classified as being indica on the basis of Wx gene product and by Glaszmann's method, but a few were classified as japonica by the glutelin α3 method and by the RFLP waxy gene probe.