Molecular Approach to the Identification of Mycorrhizal Fungi

Molecular techniques that can be used for ecological studies of arbuscular mycorrhizal fungi will be presented, such as protocols for the identification of AMF by using family-specific primers and single strand conformation polymorphism analysis. To the extent that taxonomic and phylogenetic considerations are important in the design of molecular identification tools, we will also present our results based on the study of rDNA genes from 13 species of arbuscular endomycorrhizal fungi. The recently revised morphologically based classification of arbuscular mycorrhizal fungi into 3 families, the Glomaceae, Acaulosporaceae, and Gigasporaceae, was supported by rDNA sequence data. Also, approximate dates were obtained for the divergence of major branches on the phylogenetic tree. These include an estimate of 353 – 462 Myr ago for the origin of VAM-like fungi that is consistent with the hypothesis that VAM were instrumental in the colonization of land by ancient plants.