ECOTYPIC VARIATION OF GREMMENIELLA-ABIETINA IN NORTHERN EUROPE - DISEASE PATTERNS REFLECTED BY DNA VARIATION

Genetic variation in Gremmeniella abietina isolated from Pinus sylvest ris, Pinus contorta, and Picea abies in southern and northern Fennosca ndia was studied with arbitrary primed polymerase chain reaction. Fenn oscandian G. abietina isolates were clearly separated into two ecotypi cally distinct groups based on their amplified banding patterns. Analy sis of variance based on amplified fragments, AMOVA, and principal com ponent analysis confirmed the separation of the isolates into the two groups. One group contained isolates associated with a disease syndrom e affecting young trees covered by deep snow during winter in northern Fennoscandia. The second group of isolates was found on trees between 15 and 40 years old, scattered throughout the crowns. It occurs throu ghout Fennoscandia but is most frequent in the southern pasts. No size polymorphism was found in fragments resulting after restriction enzym e digestion of internal transcribed spacer and intergenic spacer regio ns of nuclear ribosomal DNA. An estimate of gene flow between populati ons calculated based on amplified band frequencies, F-ST, indicated th at there was restricted genetic exchange between populations of the tw o groups of isolates.