A SYSTEMATIC ASSESSMENT OF MORCHELLA USING RFLP ANALYSIS OF THE 28S RIBOSOMAL-RNA GENE

Morels (Morchella spp.) are one of the most highly prized edible mushr ooms found in the wild of North America. Because environmental conditi ons can cause members of the genus to vary morphologically, the number of species has been disputed. Some authors classify the genus into th ree to five species, while others argue for as many as 50 species. DNA from lines of Morchella and a closely related genus (Verpa) was isola ted. The large subunit of the ribosomal DNA repeat was amplified using the polymerase chain reaction and then digested with restriction enzy mes. Restriction fragment length polymorphisms were found among the li nes investigated and used to separate the lines into genotypic classes . More genetic variation may occur between geographically isolated pop ulations of the same species than between two putatively distinct spec ies. The phylogenetic tree developed from restriction data suggests th at the black morels (M. angusticeps, M. elata, and M. conica) and the yellow morels (M. esculenta, M. crassipes, and M. deliciosa) are separ ate taxonomic groups.