Changes in race structure of Canadian populations ofPhytophthora infestans based on specific virulence to selected potato clones |
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| Authors: | R. D. Peters H. W. Platt R. Hall |
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| Affiliation: | (1) Crops and Livestock Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1210, PEI C1A 7M8 Charlottetown, Canada;(2) Department of Environmental Biology, University of Guelph, N1G 2W1 Guelph, ON, Canada;(3) Present address: Department of Plant Pathology, University of Wisconsin-Madison, 1630 Linden Drive, 53706 Madison, WI, USA |
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| Abstract: | Summary A collection of 80 isolates ofPhytophthora infestans, representing multilocus genotypes of the pathogen found in Canada from 1994 to 1996, was screened on a series of nine differential potato host cultivars to determine the physiological race of the isolates. A total of 28 pathotypes were found among the 11 genotypes present in the collection. There was a significant increase in the complexity of pathotypes from 1994 to 1996 which reflected the displacement of the US-1 genotype (mean of 2.2 host differentials infected) by the US-8 genotype (mean of 8.1 host differentials infected). Eighteen of the US-8 isolates could overcome all nine of the resistance genes tested. Virulence genes which overcame host resistance conferred by R8 were the rarest in the populations studied. The predominance of complex populations ofP. infestans in Canada implies that the introduction of cultivars with specific R genes for resistance would be an ineffective control measure. AAFC Contribution No. 901 |
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| Keywords: | Solanum tuberosum L. host differentials R genes multilocus genotype host-pathogen interactions |
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