ARS | Publication request: IDENTIFYING BLAST RESISTANCE IN ORYZA SP. AND FOLLOWING ITS INTROGRESSION INTO U.S. CULTIVATED RICE

Submitted to: International Rice Genetics Symposium
Publication Type: Proceedings
Publication Acceptance Date: October 22, 2000
Publication Date: N/A

Interpretive Summary: Blast is a major fungal disease affecting cultivated rice in the United States. Rice wild relatives (Oryza species) are a useful source of disease resistance genes. This research was conducted in order to identify additional sources of blast resistance genes in the rice wild relatives and incorporate these genes into rice varieties grown in the southern United States. Molecular markers developed during the past few years enhance the process of identifying blast resistance genes and following the incorporation of these genes into cultivated rice. Initial results from this research show blast resistance genes are present in the rice wild relatives. Now research is in progress to incorporate these genes into cultivated rice. U.S. rice breeders will be able to use the plant material originating from this study to incorporate additional sources of blast resistance into the new rice varieties that the breeders are developing.

Technical Abstract: Blast (Pyricularia grisea Cav.) is the major fungal disease affecting rice (Oryza sativa L.) in the USA. Wild species have often served as sources of disease resistance genes for crop plants. Research objectives were to 1) develop a method for screening Oryza sp. and their progenies for resistance to rice blast races and 2) utilize closely linked microsatellite markers in norder to follow the introgression of blast resistance from Oryza sp. into cultivated rice. Twenty-one accessions, representing O. barthii, O. glumaepatula, O. meridionalis, O. nivara and O. rufipogon, were inoculated with US blast races IB-1, IB-33, IB-49, IC-17, IE-1K, IG-1 and IH-1 and rated for susceptibility. Some O. nivara accessions and an O. rufipogon accession appeared to have resistance to certain US blast races. The Oryza sp. were crossed with the long-grain experimental line, RU9401188 and the medium-grain cultivar, Bengal. F2 progeny from these crosses and self seed from BC1 progeny were evaluated for blast resistance. Microsatellite markers which map to previously identified blast resistance regions are being utilized to follow the introgression of Oryza sp. DNA into cultivated rice. Additional markers will be screened to identify novel Pi-loci.