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

Abstract

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

The effect of nutrient supply and light intensity on tannins and mycorrhizal colonisation in Dutch heathland ecosystems

“…So, when the organic nitrogen sources become relatively less important due to increased atmospheric nitrogen, the grasses-which can benefit more from the inorganic nitrogen sources than ericaceous plants-will outcompete the heathland shrubs (Berendse and Aerts 1984). Notwithstanding the fact that the grass, Deschampsia have been shown to be also able to use organic nitrogen Falkengren-Grerup et al 2000) and even can be colonized by ericoid endophytic fungi (Zijlstra et al 2005), the highest N uptake rates are realised on ammonium and nitrate sources (Persson et al 2003). Although the responses in our experiments were different, our data from the greenhouse experiment show that increased nitrogen addition can reduce mycorrhizal colonisation, which can result in less organic nitrogen being available to the ericaceous species (Sokolovski et al 2002).…”

Effects of litters with different concentrations of phenolics on the competition between Calluna vulgaris and Deschampsia flexuosa

“…D. flexuosa seems to have adjusted to the nutrient-poor system too and is well able to use litter rich in phenolics. In addition, the fungal endophytes thought to be specific to ericaceous plants have turned out to be not that specific (Zijlstra et al 2005). The expansion of grass species after an increased input of nitrogen can still be most properly explained by their ability to respond more rapidly than ericaceous dwarf shrubs to increased nutrient supply (Berendse and Elberse 1990).…”

“…Hymenoscyphus ericae complexes of fungal strains (Zijlstra et al 2005). Such strains are able to degrade soluble phenolics (Bending and Read 1997;Zijlstra et al 2005) and enhanced significantly nitrogen uptake in inoculated D. flexuosa and C. vulgaris seedlings compared to the inoculated control plants (Zijlstra et al 2005). …”

“…But molecular analysis based on the nuclear ribosomal internal transcribed spacer (ITS) region revealed that some roots of D. flexuosa plants are colonized by beneficial fungal endophytes belonging to the Helotiales (Zijlstra et al 2005). The majority (68%) of the ericaceous root isolates analysed were found to belong to the Helotiales.…”

Paleomycology of the Princeton Chert II. Dark-septate fungi in the aquatic angiospermEorhiza arnoldiiindicate a diverse assemblage of root-colonizing fungi during the Eocene

“…It has been hypothesized that they can positively contribute to plant growth through nutrient solubilization or by water retention (Mandyam and Jumpponen 2005). The fact that some heliotealean DSE also have been shown to enhance nitrogen uptake in graminoids and eriocoids (Zijlstra et al 2005, Newsham 2011) is of particular interest when considering plants growing in inundated peat-forming mires, in that these environments generally are nitrogen poor.…”