Identification of Blast Resistance Genes in Wild Relatives of Rice (Oryza Spp.) and Newly Introduced Rice (O. sativa) Lines

摘要

Blast, Pyricularia grisea Cav., is a major fungal disease of cultivated rice (Oryza sativa L.) that limits Arkansas rough rice yields and market potential. Resistance to common U.S. blast races was observed in some rice wild relatives (Oryza spp.) and94 newly introduced cultivated rice accessions, indicating these are possible sources of unique blast resistance genes (Pi-genes) that could be incorporated into U.S. rice varieties. Pi-ta and Pi-b are major blast resistance genes that have been characterized molecularly. Objectives of this study were to identify Pi-ta and Pi-b in the aforementioned accessions and determine the relatedness of the O. sativa accessions using microsatellite markers. Results indicate Pi-ta is present in O. barthii, O. nivara, and O. rufipogon accessions and Pi-b in O. barthii, O. glumaepatula, and O. rufipogon accessions. Alleles of Pi-ta,pi-ta, and/or Pi-b were detected in 60 O. sativa accessions using dominant/recessive gene markers indicating their resistance was not new. Of the remaining 34 blast resistant accessions, 26 originated in China and potentially contain novel blast resistance genes for utilization by U.S. rice breeding programs. Genetic distance, as determined using 111 microsatellite markers, indicated some accessions had a diverse origin and many of these had good agronomic characteristics. These accessions should be useful for incorporating novel resistance to blast into advanced U.S. rice breeding lines.