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Oral: Pathogen Diversity


Microsatellite genotyping reveals high genetic diversity in Phytophthora infestans from Mexico
S. SHAKYA (1), M. Larsen (2), M. Condoy (3), H. Lozoya-Saldana (3), N. Grunwald (2) (1) OREGON STATE UNIVERSITY, U.S.A.; (2) USDA-ARS, U.S.A.; (3) Universidad Autónoma Chapingo, Mexico

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Toluca valley of Mexico is considered to be the center of origin of late blight pathogen, Phytophthora infestans. This hypothesis is supported by populations being sexual, mating type ratios 1:1 and a high standing genetic diversity in HWE. However, the population structure from other areas of Mexico is understudied. We hypothesize that migration of P. infestans outside of Toluca might have resulted in admixed population structure with decreasing diversity away from Toluca. To test this hypothesis we sampled and microsatellite genotyped more than 85 isolates from Mexico in the regions of Chapingo, Juchitepec, San Geromino, Tlaxcala and Toluca. Our analysis revealed high number of multi-locus genotypes and high allelic diversity. Juchitepec samples formed two distinct clusters suggesting two differentiated populations. Tlaxcala isolates seem to be uniformly distributed possibly indicating multiple migration events and admixture. Chapingo and San Geromino samples were more similar between them. In general, all regions showed no linkage among loci suggesting presence of sexual reproduction, except for Chapingo. Contrary to our hypothesis, diversity in other populations was even higher or comparable to Toluca. These results indicate that the center of origin is larger than previously thought. Our work provides a more refined understanding of the population structure of P. infestans in areas near Toluca where the pathogen has been well studied.