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Characterization of Phytophthora infestans populations in Canada during 2012.

Alkher, H.A., Islam, M.R., Wijekoon, C.P., Wijekoon, C.P., Kalischuk, M.L., Kawchuk, L.M., Peters, R.D., Al-Mughrabi, K.I., Conn, K.L., Dobinson, K.F., Waterer, D.R., and Daayf, F. (2015). "Characterization of Phytophthora infestans populations in Canada during 2012.", Canadian Journal of Plant Pathology, 37(3), pp. 305-314. doi : 10.1080/07060661.2015.1053987  Access to full text


The late blight pathogen (Phytophthora infestans) continues to cause major losses on potato and tomato in Canada and worldwide. An increased diversity of P. infestans and dramatic shifts in pathogen populations have occurred in Canada in recent years. In 2011, a survey identified different genotypes of P. infestans in Canada, including the new US-22, US-23 and US-24 genotypes, which were dominant in various Canadian provinces. In 2012, analysis of samples collected from infected potato and tomato plants from different regions in Canada indicated a rapid change in P. infestans populations in most provinces within a single year. For example, in Prince Edward Island, the US-8 genotype that dominated the P. infestans landscape for many years was displaced by the US-23 genotype, a phenomenon similar to that which occurred in western Canada in prior years. In British Columbia, however, US-11 and the new CA-12 were the dominant genotypes while in Ontario the tested isolates were US-22. Evidence for recombination was found, and increasing insensitivity to mefenoxam was apparent among isolates of some populations. Independent segregation of either Gpi, mating type or RG57 loci occurred in a number of the recombinant isolates, resulting in increased diversity of P. infestans populations. The unexpected change in composition of P. infestans genotypes supports the need for continued monitoring of this pathogen.

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