Submitted to: Abstract of International Horticultural Congress
Publication Type: Abstract Only
Publication Acceptance Date: 1/15/2002
Publication Date: 8/15/2002
Citation: SALDANA-LOZOYA, H., GRUNWALD, N.J., GARAY-SERRANO, E., STURBAUM, A., BROWN, C.R. POPULATION SUBSTRUCTURING OF PHYTOPHTHORA INFESTANS ON AMERICAN POTATO CLONES IN THE TOLUCA VALLEY, MEXICO. ABSTRACT OF INTERNATIONAL HORTICULTURAL CONGRESS. p 122. 2002.
Technical Abstract: A recent study highlighted the degree of genetic variability typical for a sexually reproducing population of the late blight pathogen, Phytophthora infestans, in the Toluca Valley, México (Grünwald et al, 2001). This study lends support to the idea that the Valley is an ideal location for testing potato clones for genetic resistance to the pathogen. In recent years thousands of clones from different American breeding programs have been exposed to natural infection in Toluca in the absence of fungicides. More than 100 P. infestans isolates from outstanding American potato clones were obtained between 1998 and 2000. Each isolate was obtained from a single discrete lesion. The number of samples varied depending on the incidence of the disease on one to five plants planted per clone. Mating types were identified by pairing each isolate with known A1 and A2 testers on Rye-A agar. Allozyme genotype for peptidase (Pep) and glucose-6-phosphate isomerase (Gpi) were determined on cellulose acetate membrane electrophoresis. The A1 mating type was predominant (3 : 1) with respect to A2, and homothallic cultures were identified in about 20 % of the population (A1, A2). The 100/100 Pep genotype predominated with just two isolates being of the 96/100 genotype. For Gpi six genotypes were identified, the most frequent one was 122/122, followed by 86/122. The predominant multilocus genotypes were ¿A1, 100/100, 122/122¿ (mating type, Pep, Gpi), especially on the potato clones AWN86514-2 and A90586-11. No new P. infestans genotypes were isolated from the American clones in Toluca.