Genetic diversity in Finland of the birch endophyte Gnomonia setacea as determined by RAPD-PCR markers

We studied the occurrence of genotypes of Gnomonia setacea by RAPD-PCR anal ysis at two natural sites in SW Finland to study site-, tree- and leaf-leve l genetic diversity. The analysis was performed with two primers by using 4 0 isolates from a total of 250 colonies isolated from two trees from each o f two sites. Genetic diversity of G. setacea was found to be very high: eve ry isolate studied was a unique genotype, even within the same leaf. This i s probably due to sexual reproduction and the horizontal transmission syste m of airborne spores. Genotype distribution exhibited site-level similarity , indicating limited spore deposition and the ability to form local populat ions.