Diversity of symbiotic root endophytes of the Helotiales in ericaceous plants and the grass, Deschampsia flexuosa

Root endophyte fungi of ericaceous plants were compared with those obtained from the dominant grass in Dutch heathlands, Deschampsia flexuosa. We investigated the phylogenetic relatedness of these fungi and their effects on nutrient uptake in both Calluna vulgaris and D. flexuosa seedlings in synthesis trials in vitro. Molecular analysis based on nuclear ribosomal internal transcribed spacer (ITS) region sequences revealed that four grass root endophytes belonged to the Helotiales (Ascomycetes). The majority of the ericaceous root isolates (68 %) also clustered within the Helotiales and showed a remarkably high diversity. Other important fungal groups included Phialocephala fortinii-like fungi, making up 22 % of isolates, and Cryptosporiopsis species, making up 8 %. Results of the synthesis trials showed that both grass root and ericaceous isolates colonized roots of both test host species successfully and could be seen to significantly enhance nitrogen uptake of inoculated D. flexuosa and C. vulgaris seedlings when these were compared to the uninoculated controls. We conclude that beneficial, helotialean fungi associate with roots of D. flexuosa and that these form a group potentially overlapping in phylogeny and function with endophytes from Ericaceae.