Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 15, 2004
Publication Date: January 1, 2005
Citation: Fjellstrom, R.G., McClung, A.M., Shank, A.R. 2005. Microsatellite markers closely linked to the Pi-z blast resistance gene in rice. Plant and Animal Genome Conference. p. 144.
Rice blast, caused by the fungus Magnaporthe grisea, is one of the most serious diseases threatening rice (Oryza sativa) worldwide. Plant pathologists, breeders, and geneticists are continually searching for and utilizing genes controlling resistance to rice blast. The Pi-z blast resistance gene, mapped near the centromere of rice chromosome 6, has been used throughout the world because of its wide-spectrum of blast race resistance. Previous research indicates that the Pi-z gene appears to be allelic with the Pi-2 and Pi-z blast resistance genes in rice, as well as the Pi-9 resistance gene originating in O. minuta. We have studied the inheritance of several microsatellite markers surrounding the Pi-z gene region of rice chromosome 6 in order to find microsatellites useful in marker-assisted breeding for this valuable blast resistance gene. Progeny segregating for disease resistance from three separate crosses were scored for their disease reaction to one of four blast races that are avirulent on the Pi-z or Pi-2 resistance genes. Microsatellites were genotyped in segregating progeny to map the Pi-z gene in relation to these markers. The Pi-z gene appears to be linked to microsatellite marker RM527, in close proximity to the Pi-9 gene identified by Wang et al. Results from a cross between Zenith and Pi-2 indicate that the Pi-z gene is allelic, but not identical to the Pi-2 gene. Microsatellite analysis of cultivars carrying the Pi-z, Pi-2, Pi-9, and Pi-z genes indicate that each of these resistance genes display different marker haplotypes in the Pi-z gene region.