Diversity of P hytophthora infestans from P oland

A collection of 96 P olish isolates of P hytophthora infestans sampled in the years 2006, 2008 and 2009 were analysed using phenotypic and genotypic markers. Mating type, virulence, resistance to metalaxyl, mitochondrial haplotype and polymorphism at 12 simple sequence repeat ( SSR ) loci were determined. The majority of isolates were of the A 1 mating type, mitochondrial haplotype I a and sensitive to metalaxyl. Virulence factors against potato R genes R1 , R3 , R4 , R7 , R10 and R11 were present in most isolates. Genotyping using SSR markers revealed high genetic diversity within the P olish P . infestans population. Amongst the 96 isolates 66 unique genotypes were identified, 49 of which were observed only in single isolates. Eight isolates of the genotype 13_ A 2 lineage that has been reported in other parts of E urope were also found in P oland. The implications of these results are discussed.