System of gene-for-gene interactions between rice and Magnaporthe grisea and durable plant disease resistance
2001
Li, Z.K. (International Rice Research Inst., Los Banos, Laguna (Philippines). Plant Breeding, Genetics, and Biochemistry Div.) Rey, J.D. | Bagali, P.G. | Li, X.F. | Tabien, R. | Hittalmani, S. | Cho, Y.C. | Luo, L.J. | Mei, H.W. | Loan, L.C. | Yu, S.B. | Maghirang, R. | Aquino, C. | Khush, G.S.
The hypersensitive response (HR) of rice to its blast pathogen, Magnaporthe grisea, is governed by the gene-for-gene model, in which resistance results when the pathogen carries an avirulence gene that corresponds to a specific host resistance (R) gene. In an effort to improve strategies of developing cultivars with high level and durable resistance to blast, the system of the gene-for-gene interactions between rice and more than 20 races of M. grisea were investigated using two mapping populations. Employing DNA markers, many R genes widely distributed in the rice genome were identified, which appeared to represent several groups. Based on reactions to R genes, multi-locus genotypes at corresponding avirulent loci of the M. grisea races could be inferred. Alleles at avirulent loci of the pathogen become differentiated, presumably as a result of co-evolution with allelic differentiation at the corresponding R. loci. Multiple functional alleles were present at several R. loci, though resistance could result from either indica or japonica alleles depending on the races. Associations of some R genes with tightly linked markers differ greatly when tested against different races, suggesting the possible presence of quantitative component in HR, or differential sensitivity arising possibly from varied penetrance in resistance by R. genes. It was found that none of the races could attack both parents of the mapping population. Similarly, none of the parents were resistant to all races tested. It was proposed that durable resistance could be achieved by creating both between- and within- locus heterozygosity of the R genes
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