Molecular and morphological diversity of pezizalean ectomycorrhiza.

A growing body of molecular research is discovering a high diversity of pezizalean ectomycorrhiza (EcM), yet most remain unidentified at the genus or species level. This study describes EcM-forming taxa within the Pezizales. EcM-forming Pezizales were revealed by morphotyping and sequencing of EcM root tips from forests in Estonia and Denmark. The taxa on EcM root tips were identified using phylogenetic analyses of large-subunit rDNA sequences derived from sporocarps of 301 pezizalean species, and comparisons with internal transcribed spacer rDNA sequences. Thirty-three species are suggested as EcM symbionts, representing all three major clades of Pezizales, the genera Genea, Geopora, Humaria, Tarzetta, Trichophaea, Wilcoxina, Helvella, Hydnotrya, Tuber, Pachyphloeus, Peziza and Sarcosphaera, and two Pezizaceae anamorphs. EcM of Pezizales species are easily distinguished by their anatomy, particularly thick cell walls and stout hyphae. This study demonstrates that Pezizales species constitute a considerable proportion of the mycobionts in EcM fungal communities in mature boreal deciduous and coniferous forests, in several soil types. Fruit-body sequences and EcM descriptions will facilitate identification of pezizalean EcM in future studies.