Mating Type, Race Composition, Nuclear DNA Content, and Isozyme Analysis of Peruvian Isolates of Phytophthora infestans

Tooley, P. W., Therrien, C. D., and Ritch, D. L. 1989. Mating type, race composition, nuclear DNA content, and isozyme analysis of Peruvian isolates of Phytophthora infestans. Phytopathology 79:478-481. Thirty-four isolates of Phytophthora infestans from potatoes growing in identical to Mexican, U.S., and European populations at 11 enzyme loci. the Central Highlands of Peru were analyzed. All isolates were of the Al At two polymorphic loci, Peruvian isolates showed phenotypic mating type. Feulgen cytophotometry was used to measure the DNA distributions very similar to those of U.S. and European isolates. In terms content of individual zoospore nuclei. The distribution of DNA content in of isozymes and races, fewer phenotypes were observed among Peruvian the Peruvian isolates was very similar to that previously observed in isolates isolates than among isolates from Mexico, the United States, or Europe. from the United States and Europe. Races 0, 1, and 1,5 were the most These results strongly suggest a common ancestry for Peruvian, U.S., and common among the Peruvian isolates, representing 33, 39, and 15% of the European populations of P. infestans. population, respectively. The Peruvian population was monomorphic and Late blight, caused by Phytophthora infestans, has been