Detection and analysis of genetic variations in GOB locus of Plasmopara viticola by DNA sequence analysis

The population genetic structure of Plasmopara viticola in Japan was analyzed using grapevine downy mildew specimens collected from two islands, Honshu and Hokkaido. By simple sequence repeat analysis with the GOB microsatellite marker and DNA sequencing, an accurate copy number of the (CT)n(CTAT)n repeat was determined. Consequently, we found a large number of genetic variations in (CT)n and (CTAT)n repeats. Also, a single nucleotide polymorphism in the (CTAT)n repeat of the GOB locus was detected. These genetic variations may serve as a valuable tool to understand the population structure of P. viticola.