MOLECULAR METHODS OF RESEARCH AND MONITORING OF LATE BLIGHT PATHOGEN PHYTOPHTHORA INFESTANS

The oomycete Phytophthora infestans (Mont.) de Bary, the casual agent of the late blight, still remains the main cause resulting in economic problems for potato growers. Molecular screening of (a)virulence genes of the pathogen (Avr genes) and plant genes for resistance to P. infestans (Rpi genes) would help monitor the changes in the pathogen populations and predict the most vulnerable potato varieties. To assess variation in isolates due to pathogen migration, we compared P. infestans genotypes in the isolates sampled in 2013-2015 in the Pushkin collection of interspecific hybrids (St. Petersburg) and in the commercial potato stands in several regions of Russia. The presence of two mating types, A1 and A2, also promotes pathogen variation due to sexual recombination. Molecular methods were employed for genotyping pathogen samples and assessing their mating type and Avr gene profiles. These molecular indices were related to such phenotypic characteristics as mating type, metalaxyl resistance, virulence factors tested with the differential plants and aggressiveness in the potato tuber test.