Ecology of ericoid mycorrhizal fungi: What insight have we gained with molecular tools and what’s missing?

The fungal partners involved in Ericoid mycorrhizal (ERM) associations are diverse, including many ascomycetous species falling in the Helotiales order, such as Rhizoscyphus ericae and related Meliniomyces species, Oidiodendron maius and Capronia species. The basidiomyceteous Sebacinales sub-group B also associates with ERM roots, forming coil-like intra-cellular structures. Sometimes, such as with Neotropical Vaccinioideae, sebacinales mycorrhizae include both specialized extra-cellular structures resembling ectomycorrhizal sheaths and also, unlike ectomycorrhizas, intercellular structures. Most ERM fungi are microfungi, and many are only known by their anamorphic state. Analysis of the number and provenance of rDNA-ITS sequence data deposited in the international sequence databases has highlighted the poor and inconsistent sampling of ERM associations at the global scale. Second-generation sequencing technology, coupled with international efforts to characterize fungal diversity and community structure/composition initiates the resolution of, the main biogeographical patterns governing ERM fungal communities and species.