Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/24/2002
Publication Date: N/A
Technical Abstract: Rice wild relatives, Oryza sp., are a valuable source of pest resistance genes to use for improvement of cultivated rice. Blast caused by Pyricularia grisea and sheath blight caused by Rhizoctonia solani, are the primary rice fungal diseases affecting US rice. The objectives were to screen Oryza sp. accessions and backcross progenies from crosses with rice cultivars, RU9401188 and Bengal, for resistance to US races of P. grisea and to identify microsatellite markers which could be used to follow the introgression of Oryza sp. DNA into cultivated rice. Oryza sp., F2, BC1F2 and BC2F2 progenies were inoculated with US blast at the four leaf growth stage. One week after inoculation, plants were rated for blast susceptibility using the scale of 0=no lesions to 9=large susceptible lesions and/or leaves dying. About 2-4 weeks after the first inoculation the plants were evaluated a second time by inoculating and rated newly formed leaves. Blast evaluations showed two O. nivara accessions and one O. rufipogon accession had resistance to most of the US blast races. Results from blast inoculations of the F2 progeny produced by fertile F1, BC1 and BC2 plants indicate that resistance to the blast races was transferred into US cultivars from the Oryza sp. Parent and progeny DNAs have been analyzed using microsatellite markers from each rice chromosome. Additional markers were surveyed for chromosome regions which contain known blast resistance genes (Pi- genes). Of the 57 markers surveyed to date, 21 appear to be polymorphic for at least one cross tested and useful for following the introgression of Oryza sp. DNA into cultivated rice.