ARS | Publication request: RICE GERMPLASM CHARACTERIZED FOR R-GENES AND POPULATION STRUCTURE

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 23, 2005
Publication Date: March 30, 2006
Citation: Eizenga, G.C., Agrama, H.A., Lee, F.N., Yan, W., Jia, Y. 2006. Rice germplasm characterized for R-genes and population structure. Proceedings 10th Congress of SABRAO, August 22-23, 2005, Tsukuba, Japan. CDROM.

Technical Abstract: In the USA, newly introduced rice germplasm is one source of novel resistance genes to blast, Magnaporthe grisea, and sheath blight, Rhizoctonia solani, major fungal diseases of irrigated rice (Oryza sativa). Resistance to U.S. blast races was observed in 91 of approximately 1,000 newly introduced rice accessions and these selected accessions provide possible sources of novel blast resistance genes (Pi-genes). The genes Pi-ta and Pi-b were recently introduced into U.S. cultivars and characterized molecularly. The objectives of this research were to identify new Pi-genes in the aforementioned accessions by differentiating known Pi-genes, determining the relatedness of the accessions with SSR markers, and identifying marker-trait associations with disease resistance traits. Twenty-five accessions were identified as resistant to U.S. blast races and had neither the Pi-ta nor Pi-b gene. Based on 125 SSR markers distributed over the rice genome, eleven of the 25 accessions were closely related to each other. Population structure analysis indicated the 91 accessions had six separate ancestries, all of which differed from the ancestry of U.S. cultivars included for comparison. Blast resistance traits were associated with 32 of the 125 SSR markers and sheath blight traits with 19 markers. Twelve markers were in regions previously not associated with blast and these will be the basis for discovering additional Pi-genes.