Extraction of DNA from Basidiomycetes for ribosomal DNA hybridizations

We describe a method for extracting high molecular weight DNA from milligram amounts of fungus specimens. DNA extracted from 1 – 100 mg of fresh, air-dried, or lyophilized tissue was sufficient for 1–50 Southern hybridizations. Typical yields were 1 – 10 nanograms (ng) of DNA per milligram of starting material for fresh and air-dried samples, and 50–500 ng/mg for lyophilized samples. Of the 78 samples from 63 species of saprobic and ectomycorrhizal Basidiomycetes, all but one yielded measurable amounts of nucleic acids. The DNA was used for restriction enzyme ribosomal DNA hybridizations. While most species showed similarities in the genic regions, significant size variation was seen in the intergenic regions, in most cases allowing for distinction between samples at the species level.