Trudy B. M.
van den Bosch
First, sixth, seventh, and tenth authors: Department of Plant Pathology, Cornell University, Ithaca, NY 14853; first, third, fourth, and eighth authors: CEEM/PICTIPAPA Potato Late Blight Project, Apartado postal 3-2, Izcalli Cuauhtemoc V, Metepec, Edo. de México 52176, Mexico; second, fifth, and ninth authors: Plant Research International, P.O. Box 16, 6700 AA Wageningen, the Netherland; and eighth author: Departamento de Fitotecnia, Universidad Autónoma Chapingo, 56230, Chapingo, Edo. de México, Mexico
Go to article:
Accepted for publication 21 May 2001.
We tested the hypothesis that the population of Phytophthora infestans in the Toluca valley region is genetically differentiated according to habitat. Isolates were sampled in three habitats from (i) wild Solanum spp. (WILD), (ii) land-race varieties in low-input production systems (RURAL), and (iii) modern cultivars in high-input agriculture (VALLEY). Isolates were sampled in 1988-89 (n= 179) and in 1997-98 (n= 389). In both sampling periods, the greatest genetic diversity was observed in RURAL and VALLEY habitats. Based on the Glucose-6-phosphate isomerase and Peptidase allozymes, the subpopulations from the three habitats were significantly differentiated in both sampling periods. In contrast to allozyme data for 1997-98, no differences were found among the three subpopulations for sensitivity to metalaxyl. Two groups of isolates identical for allozyme and mating type were further investigated by restriction fragment length polymorphism fingerprinting; 65% of one group and 85% of another group were demonstrated to be unique. The genetic diversity data and the chronology of disease occurrence during the season are consistent with the hypothesis that populations of P. infestans on wild Solanum populations are derived from populations on cultivated potatoes in the central highlands of Mexico near Toluca.
potato late blight
© 2001 The American Phytopathological Society