TAXONOMY AND POPULATION-STRUCTURE OF E-STRAIN MYCORRHIZAL FUNGI INFERRED FROM RIBOSOMAL AND MITOCHONDRIAL-DNA POLYMORPHISMS

E-strain fungi from ecto- and ectendomycorrhizal associations with many trees, and are important mycorrhizal symbionts in disturbed forest habitats and conifer nurseries. Unlike the majority of mycorrhizal fungi, which are basidiomycetes, E-strain fungi are ascomycetes belonging to the genus Wilcoxina (Pezizales). We analysed variation in the nuclear and mitochondrial ribosomal RNA genes to elucidate species concepts among E-strain fungi and to examine their population structure. We found that most E-strain isolates can be assigned to two taxa, W. mikolae and W. rehmii, that have different habitat preferences. Wilcoxina mikolae is the predominant taxon in disturbed forest habitats on soils that are often low in organic matter, such as burned sites, while W. rehmii prefers peaty soils. Analysis of mitochondrial DNA also revealed that within each species, isolates could be differentiated based upon host preference. This is the first report of population subdivision based upon host in E-strain fungi.