Genetic characterization of isolates of Pseudoperonospora cubensis causing downy mildew in different countries using molecular markers

Abstract

Downy mildew caused by Pseudoperonospora cubensis is a major disease of cucurbits worldwide. In cucumber it causes serious economic yield losses. P. cubensis has a high degree of evolution potential. The recent appearance of new genotypes of the pathogen in the USA, EU and Israel resulted in the breakdown of genetic resistance and expansion of host range. Therefore, revealing the pathogen diversity is required. In this study, pathogen isolates were collected during 20082010 from cucumber fields in different regions of Turkey, Israel and The Czech Republic and genetically compared using SSR, ISSR and SRAP molecular markers. The data showed remarkable genetic diversity among and between isolates recovered in Israel, Turkey and The Czech Republic. The isolates from Israel were clearly distinguished from those recovered in Turkey or The Czech Republic. The isolates from Turkey and The Czech Republic were highly variable. These findings mayt indicate sexual recombinations in nature and support the notion that selected molecular markers can be used to follow genetic differentiation in P. cubensis isolates.