Genomic fingerprinting supports the separation of Ophiostoma piceae into two species

Abstract

Fourteen isolates of Ophiostoma piceae from diverse regions and hosts across Europe and North America, which had been assigned to the OPC (conifer) and OPH (hardwood) species groups on the basis of their reproductive isolation, were compared by molecular methods. The randomly amplified polymorphic DNA (RAPD) banding patterns of the isolates generated by 33 random oligonucleotides showed a very high level of variation, allowing all 14 isolates to be distinguished from each other. Eight primers produced bands unique to all seven OPC isolates and six primers produced bands unique to all seven OPH isolates. Hybridization probes based on RAPD bands and ribosomal DNA also provided clear separation of the two groups. These results support the designation of the OPC and OPH groups as separate species. The molecular analyses also confirmed that some OPH and OPC isolates occurred on the atypical host type, including an OPC isolate that was recovered from elm bark colonized by Dutch elm disease ophiostomas. The reinstatement of the name O. quercus (Georgev.) Nannf. for the OPH group is recommended.