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Poster: Epidemiology: Population Biology Genetics


A shift in the population of Phytophthora infestans on Egyptian potato crops.
S. EL-GANAINY (1), Y. Ahmed (1), M. Soliman (1), A. Ismail (1), A. Tohamy (1), E. Randall (2), D. Cooke (2) (1) Plant Pathology Research Institute, Egypt; (2) The James Hutton Institute, Scotland

Potato is an economically important crop in Egypt that is cultivated over three growing seasons, summer, fall (Nili) and winter. The winter crop that is grown from September to the end of February is particularly prone to late blight caused by Phytophthora infestans due to weather conditions that are conducive from the start of November and many crops suffer severe yield losses. We obtained 145 purified P. infestans isolates from the 2013 and 2014 winter crops which were genotyped using 12 SSR markers to generate data that would inform disease management. In contrast to previous work (3-year period 2010-12) in which the 13_A2 lineage was found, all isolates belonged to the 23_A1 lineage. There was no evidence for the existence of the A2 mating type or 13_A2 lineage even in the destroyed field crops of some cultivars (Cara, Bellini and Valor) that had been reported as resistant to 23_A1. This suggests that the previously reported virulence profile of 23_A1 has changed. Unlike 13_A2 the 23_A1 genotype is reported as sensitive to intermediate in response to metalaxyl. Polymorphisms in mainly 3 loci (SSR3, G11 and D13) discriminated 14 sub-clonal lineages of 23_A1 in Egypt suggesting the population has been present in Egypt for several years. The data have entered into the Euroblight database to allow temporal and spatial genetic diversity to be examined in comparison with other regional P. infestans populations.