ARS | Publication request: Phytophthora Infestans; Races Vs Genotypes in the Toluca Valley, Mexico.

Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2005
Publication Date: March 10, 2006
Citation: Lozoya-Saldana, H., Barrios, O., Bamberg, J.B. 2006. Phytophthora infestans; races vs genotypes in the Toluca Valley, Mexico [abstract]. American Journal of Potato Research. 83:122

Technical Abstract: The A1 and A2 mating types of Phytophthora infestans (P.i.) are continuously present in the Toluca Valley, México. As a consequence, a great deal of its progeny is sexually derived into a wide genetic diversity, frequently reported either as races or genotypes. This study deals with the characterization of P.i. populations under these two classifications. Sixty three isolates of the oomycete were obtained from indicator plants exposed to natural infection in the Valley in the summer of 2004. The first races to show up were R1 to R4, followed by the rest of the races, except R9, which incidence increased during the second half of the season. Two to seven isolates per indicator plant (race) were obtained, and in most of the cases the populations were different within a race regarding glucose phosphate isomerase (Gpi), peptidase (Pep), mating type (MT), and metalaxyl resistance. On the other hand, the most common genotype was (Gpi, Pep,MT, MR) 100/100, 86/100, A1, sensitive to metalaxyl (twelve isolates, 19% of the total population), and all of the isolates within this profile corresponded to different races. These preliminary results indicate that the two systems to characterize P.i. populations are not related.