Phylogenetic resolution of Morchella, Verpa, and Disciotis [Pezizales: Morchellaceae] based on restriction enzyme analysis of the 28S ribosomal RNA gene.

The large subunit (28S) of the ribosomal DNA repeat of Morchella, Verpa, and Disciotis and a closely related genus (Gyromitra) was enzymatically amplified via the polymerase chain reaction. Restriction fragment length polymorphisms were found among the lines investigated and used to infer phylogenetic relationships. More variability was observed toward the 5' end than toward the 3' end of the 28S rRNA gene. The RFLP data were used to assemble a phylogenetic tree for the taxonomic group. Based on the RFLP data three black Morchella species isolates differed by approximately 0.5, 1.0, and 1.5%, respectively, from all other isolates in the Morchellaceae examined in this study. Gyromitra gigas, used as an outgroup, had approximately 6.2% difference from all members of the Morchellaceae. In some cases more genetic variation was observed intraspecifically than between putative species. Additionally, the hypothesis that Morchella is composed of only a few (possibly three) polymorphic species was supported by our findings.