Mitochondrial DNA diversity and lineage determination of European isolates of Fusarium graminearum (Gibberella zeae).

Restriction fragment length polymorphisms (RFLPs) were used to assess genetic diversity of mitochondrial DNA (mtDNA) among standard isolates of seven lineages of Fusarium graminearum. The mtDNA patterns within each lineage were very similar (>89%), whereas significant differences were observed between the isolates belonging to different lineages, with the exception of lineages 1 and 4 where strong similarity was found between the RFLPs. Analysis of different band patterns resulted in characteristic HhaI and HaeIII bands that were suitable for identification of members of lineages 7, 6, 5, 3 and 2. Investigation of lineage distribution of 144 European isolates revealed that 142 belong to lineage 7. These data, therefore, confirmed the hypothesis that members of lineage 7 are predominant in Europe. Further analysis of isolates belonging to lineage 7 resulted in five haplotypes. These haplotypes have arisen as different combinations of three RFLP patterns for both HaeIII and HhaI restriction enzymes. Two isolates from Hungary, however, shared the same mtDNA RFLP profiles with a standard isolate of lineage 3, indicating that members of lineage 3, at a lower frequency, may also occur in Europe.