Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 12, 2001
Publication Date: N/A
Technical Abstract: Rice wild relatives, Oryza sp., are valuable sources of pest resistant genes. Blast (Pyricularia grisea (Cooke) Sacc.) and sheath blight (Rhizoctonia solani K¿hn) are the primary rice fungal diseases in the U.S. Oryza sp. accessions reported in previous studies to be sheath blight resistant were screened for resistance to U.S. isolates of sheath blight and blast. Attempts were made to cross the accessions with cultivated ric (Oryza sativa L.) using both a long grain experimental line, RU9401188, and a medium grain cultivar, 'Bengal', as parents. F1, BC1, BC2 and BC3 progenies were obtained from crosses with four O. nivara accessions and one O. rufipogon accession. Both O. nivara and O. rufipogon have an A-genome similar to the A-genome found in cultivated rice. Initially microsatellite markers associated with blast resistance genes (Pi-genes) were selected. Next, additional markers were selected for each chromosome arm not represented by markers associated with blast resistance, thus, microsatellite markers representing all 24 chromosome arms were chosen to follow the introgression of these Oryza sp. DNAs into cultivated rice. Parental DNAs were surveyed to determine which marker gave reproducible bands and if the marker was polymorphic for the parental lines. One fourth of the markers selected fit this description and are being used to follow the introgression of Oryza sp. DNA into backcross progenies with cultivated rice. Pi-specific primers (Pi-ta, Pi-b) are being used to search for known resistance genes in these populations and other microsatellite markers are being screened to identify additional useful markers.