High genotypic diversity found among population of Phytophthora infestans collected in Estonia.

Potato late blight, caused by the oomycete pathogen Phytophthora infestans, is one of the most important diseases of potato worldwide. This is the first study characterising Estonian P. infestans population using the SSR marker genotyping method. 70 P. infestans isolates collected during the growing season in 2004 from eight potato fields in three different regions of Estonia were characterised with nine polymorphic SSR markers. A1 and A2 mating type isolates were detected from every studied field indicating the high potential for sexual reproduction, which raises the genotypic diversity in P. infestans population. Results revealed highly diverse P. infestans population in Estonia resembling the Northern European populations. Most of the multilocus genotypes were detected only once among the collected isolates. Subpopulations collected from different geographical regions of Estonia showed no differentiation from each other but instead formed one highly diverse group.