We have developed a DNA-based assay to reliably detect brown rot and white rot fungi in wood at different stages of decay. DNA, isolated by a series of CTAB and organic extractions, was amplified by the polymerase chain reaction using published universal primers and basidiomycete-specific primers derived from ribosomal DNA sequences. We have surveyed 7 species of brown rot fungi, 7 species of white rot fungi, 1 ectomychorrizal basidiomycete, 1 non-wood decay basidiomycete species, 25 species of wood-inhabiting ascomyetes (pathogens, endophytes, and saprophytes) and 2 species of non-wood-inhabiting ascomycetes. DNA was isolated from pure cultures of these fungi. DNA was also isolated from spruce wood blocks colonized for 8 months by individual wood decay isolates or isolates of some of the wood-inhabiting ascomycetes. Wood blocks inoculated with species of brown rot fungi exhibited more decay as measured by percent weight loss (65.5 to 69.6%) after 8 months than those inoculated with white rot fungi (0 to 40.1%) or wood-inhabiting ascomycetes (0 to 2.7%). The primer pair ITS1-F (specific for higher fungi) and ITS4 (universal primer) amplified the internal transcribed spacer region from both ascomycetes and basidiomycetes from both pure culture and inoculated spruce wood, as expected. The primer pair ITS1 -F (specific for higher fungi) and ITS4-B (specific for basidiomycetes) were shown to reliably detect the presence of wood decay basidiomycetes in both pure culture and wood; however, ascomycetes were not detected by this primer pair. We detected the presence of decay fungi in wood by PCR before measurable weight loss had occurred to the wood.

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