Polymorphisms in the large intergenic spacer of the nuclear ribosomal repeat identify Laccaria proxima strains

A simple method for identifying strains of Laccaria proxima is presented which uses the polymerase chain reaction (PCR) to amplify the large intergenic spacer region of the nuclear ribosomal repeat. The large intergenic spacer region of L. proxima is approximately 4000 base pairs long and is variable enough to permit clear identification of individual strains after digestion with restriction endonucleases. This has only been partially possible with other published PCR-based identification methods which use conserved primers. The method has the potential to be adapted for use in identifying isolates directly from roots and avoids the use of labeled probes needed for identifying Laccaria strains with techniques which are not PCR-based.