Identification of nematode-trapping fungi using RFLP analysis of the PCR-amplified ITS region of ribosomal DNA

Six isolates of Arthrobotrys oligospora var. oligospora, identified by morphological characters, were screened for polymorphism in the ITS region of the ribosomal DNA. RFLPs produced with four different endonucleases were identical for five out of six isolates. The RFLP patterns were also compared to those from the ITS regions of other Arthrobotrys species as well as to other nematophagous fungi. All species tested produced unique RFLP patterns which could be distinguished from each other easily. The results suggest this method to be a good tool for fast identification of large numbers of isolates in screening assays. Only minute colonies are needed since enough amplification product could be obtained from 0.1 ng of total genomic DNA. The method can also be useful in verifying the true identity of isolates which are difficult to type morphologically.