Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2003
Publication Date: 9/1/2004
Citation: Fjellstrom, R.G., Bormans, C.A., Marchetti, M.A., Shank, A.R., Park, W.A., McClung, A.M. 2004. Development of dna markers suitable for marker assisted selection of three pi- genes conferring resistance to multiple Pyricularia grisea pathotypes. Crop Science. 44:1790-1798. Interpretive Summary: Rice blast is a serious disease in rice causing considerable economic damage worldwide. It would be useful to have DNA markers indicating the presence of blast resistance genes in order to effectively develop rice varieties that can withstand this disease threat. DNA markers for rice blast resistance have been reported by other research groups, but most of these markers are not suitable for routine use in a marker-assisted selection breeding program involving large numbers of progeny. This research paper presents the development of several DNA markers that can be rapidly and efficiently assayed for the selection of blast disease resistance in rice breeding lines. Three to five DNA markers tightly linked with each of three independent blast resistance genes are reported. These markers allow marker-assisted selection of all three blast resistance genes simultaneously, which would be extremely difficult and costly to do if they were not available. Since each of the three genes with DNA markers provides resistance to multiple pathotypes of the blast fungus found in the U.S., these markers can be used to develop new rice cultivars having resistance to all the predominant races of blast found in the U.S.
Technical Abstract: Rice blast is a serious disease in rice causing considerable economic damage worldwide. DNA markers for rice blast resistance have been developed, but most are not suitable for routine use in a marker-assisted selection breeding program involving large numbers of progeny. After identifying candidate microsatellite markers from public database sources, we have mapped these markers near the blast resistance genes Pi-b, Pi-k, and Pi-ta2 on chromosomes 2, 11, and 12, respectively, of rice using segregation information from hundreds of progeny in several crosses. The new markers are polymorphic in narrow crosses characteristic of applied breeding programs and appear to be ideally suited for marker assisted selection because of their tight linkage with resistance genes and ease of use through analysis of amplification products. A dominant marker indicating the presence of the Pi-b gene has also been developed based on the published sequence of the cloned Pi-b gene. These markers should facilitate the introgression and pyramiding of blast resistance genes into new rice cultivars.