Genotypes of the late blight pathogen (Phytophthora infestans) in British Columbia and other regions of Canada during 1993-1997

Abstract

Isolates of Phytophthora infestans were collected from British Columbia at various times during 1993-1997 and from eight other provinces in Canada during 1993-1995 and characterized for mating type (either Al or A2), growth response to metalaxyl (either sensitive-MS or insensitive-MI), and random amplified polymorphic DNA (RAPD) patterns. Among the isolates tested, 312 were from diseased potato cultivars, while 14 originated from tomato or hairy nightshade plants with blight symptoms. A composite of RAPD patterns generated by nine primers following PCR amplification was used to identify novel genotypes based on presence of polymorphic bands. The occurrence in Canada of genotypes that corresponded to US I, US 6, US 7, and US 8 was confirmed during this study. The RAPD primers also identified 15 novel genotypes from British Columbia (BC) and 4 from New Brunswick, regions in which both Al and A2 mating types of P. infestans have previously been found and oospore production reported. In 1993, genotypes US 6 a...