Abstract
Phytophthora infestans (Mont.) de Bary is a destructive potato pathogen. Changing weather conditions are among the factors that influence the pathogen population structure. In this study, 237 P. infestans isolates were collected from a single unprotected experimental field in an area with high late-blight pressure located in Boguchwała in the southeastern part of Poland during 15 growing seasons (2000–2014). The isolates were assessed for mating type, mitochondrial haplotype, resistance to metalaxyl, virulence, and polymorphism of 14 single-sequence repeat markers (SSRs). The results revealed 89 unique genotypes among the 237 P. infestans isolates. Eighty-seven isolates belonged to genotype 34_A1, which was detected in all the years of research except 2012. Isolates of P. infestans from individual years were very similar to each other, as shown by Nei’s genetic identity based on 14 SSR markers. The obtained results on isolate characteristics were analyzed in terms of meteorological data (air temperature and precipitation) and indicated that frost, long winters, and hot, dry summers did not directly affect the P. infestans population structure. We described the variability in metalaxyl resistance and virulence among isolates of the P. infestans genotype 34_A1.
Highlights
Late blight, caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary, is one of the most economically damaging potato (Solanum tuberosum L.) and tomato (Solanum lycopersicum L.) diseases globally
Almost all (99%) of the P. infestans isolates were virulent toward plants with the R1, R3, R4, and R7 genes
The population structure of P. infestans isolates collected from one experimental, unprotected field in Boguchwała was analyzed over a long period to check the impact of weather conditions on the genetic diversity of the pathogen in different years
Summary
The aim of this study was to determine the effect of weather conditions on the P. infestans population structure that was monitored during 15 growing seasons in one location in Poland. Through analyses of data on the diversity of tested isolates in the context of weather conditions during the growing seasons and winters, we aimed to test the hypothesis that cold winters limit the spread of clonal lineages by hampering the survival of mycelia and sporangia while simultaneously promoting diverse, sexually recombined strains of P. infestans derived from oospores
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