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Oral: Plant Pathologists of the Future: Showcasing the Top Graduate Students from APS Division Meetings


Physiological races and genetic diversity of isolates of Phytophthora capsici from Mexican crop production fields.
A. CASTRO ROCHA (1), P. Osuna Avila (2), S. Shrestha (3), R. Lyon (4), G. Rodíguez Alvarado (5), S. Fernández Pavía (5), K. Lamour (3) (1) Universidad Autónoma de Ciudad Juárez, Mexico; (2) Universidad Autónoma de Ciudad Juárez, Mexico; (3) University of

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Phytophthora capsici is a fungal-like oomycete plant pathogen that causes serious loss to pepper and tomato in Mexico. Our objectives were to characterize isolates from crop production fields for race type and genotypic diversity. Race types were established for five isolates recovered from Aguascalientes, Chihuahua, Guanajuato, Michoacán and Estado de México, towards two sets of differential hosts. Each interaction was tested 20 times. One set of differential hosts contained 26 New Mexico Recombinant Inbred Lines (NM-RILs) of pepper. The NM-RILs revealed two new physiological races. The second differential contained 7 commercial pepper cultivars and differentiated one isolate that was not differentiated using the NM-RIL panel. Genetic diversity was assessed for 81 isolates of P. capsici from the Northern and Central regions using a targeted sequencing approach. A total of 33 single nucleotide polymorphism (SNP) sites, previously used for population studies of P. capsici in China, were genotyped. Sequence analysis revealed 70 unique and 4 repeated multi locus genotypes. These findings, in total, suggest there is significant genetic diversity in vegetable production regions of Mexico and multiple race types. Implications for survival and spread will be discussed.