Genetic differentiation within the European race of Gremmeniella abietina

Twelve random amplified polymorphic DNA markers were variable within the European race of Gremmeniella abietina var. abietina (GAA-EU) in Europe. Three distinct DNA amplification profiles (amplitypes) appeared to be correlated with ecotypic origin. The northern amplitype was present exclusively in northern Europe in plantations and natural stands of Pinus sylvestris and in plantations of P. contorta and apparently was adapted to the presence of deep, long-lasting snow cover in the winter. An alpine amplitype was found exclusively in the Alps at altitudes above 2000 m on P. cembra, P. mugo, P. sylvestris and Larix lyalli and also appears to represent an ecotype adapted to conditions of deep snow cover. The third amplitype, the European amplitype, was present throughout Europe and ranged from the Scandinavian countries and extended south to the Apennine mountains of northern Italy. Most of the GAA-EU samples tested from North America had RAPD profiles identical to those of the European amplitype indicating that the origin of this introduced pathogen could be central Europe. However, some of the samples from North America had RAPD profiles that did not match any found in Europe. The internal transcribed spacers of the ribosomal DNA repeat subunit were amplified and digested with restriction enzymes Hae III and Msp I. These restriction sites were polymorphic between the North American (GAA-NA) race and the EU race of G. abietina but were homogeneous among the three amplitypes described above. The rDNA restriction and RAPD profiles also indicated that GAA-NA was absent from the samples from Europe and that symptoms resembling those caused by GAA-NA were attributable to the northern and alpine amplitypes.