Comparison of General Fungal and Basidiomycete-specific ITS Primers for Identification of Wood Decay Fungi
The identity of the fungi associated with and responsible for wood decay could lead to the development of more environmentally benign wood preservative systems. In this study we have reconstructed the phylogenetic tree of a select group of basidiomycete fungi using nucleotide sequences of the internal transcribed spacer (ITS) region. We then compared this to trees generated from restriction fragment length polymorphism (RFLP) analysis using two different primers to see if the latter procedures can correctly identify multiple isolates of select wood decay fungi. The phylogenetic tree using maximum likelihood analysis revealed three well-supported genera, Trametes, Phanerochaete, and Gloeophyllum, with bootstrap values of 75 or greater. Trametes and Phanerochaete were sister taxa, and Gloeophyllum was a sister taxon to the Trametes/Phanerochaete clade. Neither set of RFLP data could resolve the three genera into monophyletic groups. The RFLP tree based on general fungal primers also did not resolve species, while the basidiomycete-specific data could resolve species. In the basidiomycete-specific tree, all isolates of both G. striatum and G. trabeum comprised monophyletic groups. Eight of nine T. versicolor isolates, 10 of 11 G. sepiarium isolates, and nine of 10 T. hirsuta isolates comprised monophyletic groups. Phanerochaete could not be consistently resolved into monophyletic groups at either the generic or specific level. Our studies indicate that RFLP analysis using general fungal primers are not likely to be useful in identifying species or reconstructing phylogenetic relationships. RFLP analysis using basidiomycete-specific primers may be useful in identifying some species but not in reconstructing phylogenetic relationships although it is a simpler procedure than sequencing.