Identification of European Armillaria species by restriction‐fragment‐length polymorphisms of ribosomal DNA

Summary Identification of European Armillaria species using ribosomal DNA (rDNA) restriction-fragment-length polymorphisms (RFLPs) was studied. A total of 44 Armillaria isolates representing five European biological species were examined. Whole-cell DNAs were digested with one or two (double digest) restriction endonucleases and probed with a cloned plasmid carrying one complete rDNA repeat copy of Saccharomyces carlsbergensis. Applying the restriction endonuclease Bgl II in combination with either Eco RI, Bam Hl or Hin dIII, it was possible to detect rDNA RFLPs allowing differentiation between all five European Armillaria species investigated in the study. The most conclusive results were obtained in the rDNA/Ava II RFLP pattern. All biological species showed unique Ava II banding patterns. Generally speaking, the interspecific similarities were around 42% and lower, indicating a distinct species separation. The analysis of rDNA RFLP patterns by a restriction-enzyme-rDNA-probe combination (for instance, Ava II or Bgl II/Hin dIII; probe pMY 60) is a practical means of identifying European Armillaria species for further taxonomic, phylogenetic and host-pathogen interaction studies.