Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2005
Publication Date: 11/6/2005
Citation: Eizenga, G.C., Agrama, H.A., Lee, F.N. 2005. Identifying novel R-genes in rice wild relatives with microsatellite markers [abstract]. American Society of Agronomy Abstracts, November 6-9, 2005, Salt Lake City, Utah. 2005 CDROM.
Technical Abstract: Rice wild relatives (Oryza spp.) are an important source of novel R(resistance)-genes for rice improvement. Rice sheath blight, caused by Rhizoctonia solani, and leaf blast, caused by Magnaporthe grisea, are major fungal diseases of cultivated rice (O. sativa) in the USA and of irrigated rice worldwide. To identify novel resistance genes, approximately 50 accessions representing the species O. alta, O. australiensis, O. barthii, O. glaberrima, O. glumapatula, O. latifolia, O. meridionolis, O. nirvara, O. officinalis, and O. rufipogon, were screened for reaction to M. grisea and R. solani. Ten different blast races, each represented by a single isolate of M. grisea, and single isolate of R. solani were used in the greenhouse disease screening. These accessions were genotyped with approximately 200 SSR markers and data from 138 SR markers used to conduct genetic distance and cluster analysis on these accessions with the PowerMarker program. Preliminary data indicated a close relationship between many O. barthii, O. nirvara and O. rufipogon accessions, the progenitors of cultivated rice. One O. nivara accession clustered closely with five U.S. rice cultivars included for comparison. Clustering was more distant between U.S. cultivars and accessions of the remaining Oryza spp. that were not progenitor species. Associations between the aforementioned SSR markers and the disease reactions of the Oryza spp. accessions to blast races and sheath blight also were delineated using the PowerMarker program. Preliminary analysis with eight blast races identified 34 markers associated with two or more blast races. These associations will be used to identify the regions where novel R-genes are located. To date, six accessions are being backcrossed to adapted U.S. germplasm for mapping population development to further analyze the R-genes and to select germplasm useful to U.S. rice breeding programs.