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- Genetic structure of Magnaporthe oryzae B.C. Couch populations from...
Genetic structure of Magnaporthe oryzae B.C. Couch populations from farmers’ fields and experimental plots in the Philippines
Dissertation Abstract:
This study determined the current genetic diversity of populations of Magnaporthe oryzae, the rice blast pathogen. A total of 453 monocodial isolates
recently collected from farmers’ fields and experimental plots in various geographic areas of the Philippines were genotyped using 13 microsatellite markers. Three major genetic groups, composed of 93 new multi-locus genotypes, were determined in the collection when compared with the reference strains representing the genotypes previously published. Analysis showed that those collected from Luzon and Visayas were genetically similar while those from Mindanao were genetically different. Low diversity was noted in isolates collected from experimental plots and from lowland areas.
Fertility and mating type test revealed the presence of sexually fertile isolates
and both mating types MATI.1 and MATI.2 were found. Significant associations were noted on specific avirulence genes and types of agroecosystems. Avirulence genes would prevail in areas where the complementary resistance genes exist. Additionally, pathogenicity test identified candidate resistance genes Pil, Pi33, Pi9, Pikm, and Piz-Pish, while PCR test showed the complementary resistance genes Pik, Pita, and Pii to be useful in breeding for blast resistant rice cultivars. These resistance genes can be sourced from the upland varieties locally known as ‘Milagrosa’ and ‘Waray’.