Diversity of fungi in hair roots of Ericaceae varies along a vegetation gradient

Abstract

Ericaceous dwarf shrubs including Calluna vulgaris and Vaccinium spp. occur both in open heathland communities and in forest ecosystems as understory vegetation. Ericaceous shrubs were once thought to form ericoid mycorrhizal associations with a relatively narrow range of ascomycetous fungi closely related to, and including, Rhizoscyphus ericae. However, perceptions have recently changed since the realization that a broader range of ascomycete fungi, and in some cases basidiomycete fungi, can also form associations with the roots of ericaceous plants. We used a combination of molecular approaches, including denaturing gradient gel electrophoresis, terminal restriction fragment length polymorphism, cloning and sequencing, to investigate the diversity of fungi associated with C. vulgaris roots collected across a heathland/native Scots pine forest vegetation gradient. We also determined differences in fungal community composition between roots of co-occurring C. vulgaris and Vaccinium myrtillus in the forest understory. Collectively, the data show that a large diversity of potentially ericoid mycorrhizal fungal taxa associate with roots of C. vulgaris and V. myrtillus, and that ascomycetes were about 2.5 times more frequent than basidiomycetes. The assemblages of fungi associated with C. vulgaris and V. myrtillus were different. In addition, the community of fungi associated with C. vulgaris hair roots was different for samples collected from the forest, open heathland and a transition zone between the two. This separation was partly, but not entirely, due to the occurrence of typical ectomycorrhizal basidiomycetes associated with the hair roots of C. vulgaris in the forest understory. These data demonstrate that forest understory ericaceous shrubs associate with a diverse range of ascomycete and basidiomycete taxa, including typical ectomycorrhizal basidiomycetes.

Experimental evidence of ericoid mycorrhizal potential within Serendipitaceae (Sebacinales)

“…On the one hand, experimental corroboration as well as investigation of the mechanisms underlying the evolution of this specificity are limited by the absence of (Kottke et al 2008;Setaro et al 2013). This is surprising, considering the generally broad spectrum of Ericaceae root mycobionts and the apparent ability of Ericaceae to associate with many nonspecific root endophytes co-occurring in the roots of the surrounding vegetation (Bougoure et al 2007;Tedersoo et al 2009;Vohník et al 2013). Indeed, most of the Orchidaceae-derived isolates tested in this study were able to intracellularly colonize apparently healthy roots of the model Ericaceae host.…”

Disruption of root carbon transport into forest humus stimulates fungal opportunists at the expense of mycorrhizal fungi

“…PCR products with 99-100% sequence similarity to the most commonly detected Leptodontidium genotype have also been amplified from coniferous forest soils in Canada, Alaska and eastern USA, as well as from hair roots of ericaceous shrubs in Scotland (Bougoure et al, 2007). The ecology of Capronia species is uncertain; pathogenic, mycoparasitic as well as lichen forming taxa have been described, but their capacity as primary saprotrophs of plant litter has been questioned (Untereiner and Malloch, 1999).…”

Identification and community profiling of Vaccinium membranaceum root-associated fungi over an elevation gradient in BC's eastern rocky mountains.

“…Similar studies that exploit natural gradients to find patterns of mycorrhizal community structure have been done (Bougoure et al 2007;Kernaghan and Harper 2001;Mulder and de Zwart 2003;Nilsson et al 2005). Bougoure et al (2007) examined both Calluna vulgaris (L.) Hull and Vaccinium myrtillus L. root-associated fungal community structure along a heath to forest gradient in Scotland using denaturing gradient gel electrophoresis, terminal restriction fragment length polymorphism and cloning and sequencing.…”

“…The challenge, then, is to measure appropriate variables that will help explain differences observed in the field. Naturally occurring gradients of vegetation, forest productivity, microclimate, soil nitrogen availability, and soil pH have been exploited to show differences in mycorrhizal assemblages in changing field environments (Bougoure et al 2007;Mulder and de Zwart 2003;Nilsson et al 2005). …”

“…Bougoure et al (2007) examined both Calluna vulgaris (L.) Hull and Vaccinium myrtillus L. root-associated fungal community structure along a heath to forest gradient in Scotland using denaturing gradient gel electrophoresis, terminal restriction fragment length polymorphism and cloning and sequencing. They found the fungal community composition did not differ for V. myrtillus between their sites, whereas it did for C.…”