Fungi associated with aeroponic roots in caves and mines of New Brunswick. Root Associated Fungi in New Brunswick Caves and Mines

We provide the first analysis of the fungi associated with a very special habitat, the aeroponic roots found in caves and mines in New Brunswick, Canada. Fungal diversity was assessed by Illumina sequencing using three complementary primer sets targeting ribosomal RNA genes, and roots were identified using the non-coding trnH-psbA spacer. Early colonizing ectomycorrhizal fungi such as Agaricales, Helotiales, Pezizales, and Thelephorales were predominant. Saprotrophs, endophytes and plant pathogens were also present, but Glomeromycota (arbuscular mycorrhizal fungi) were not detected. Fungal root communities were generally most similar within sites. Fungal diversity was inversely correlated with winter dark zone temperatures and distance from the entrance. By using a combination of three primer sets, we detected more fungal taxa than with any one primer set. This study adds to the understanding of these subterranean ecosystems and suggests that future studies investigate factors limiting the presence of late-stage ectomycorrhizal fungi and Glomeromycota.

本研究首次针对加拿大新不伦瑞克省洞穴与矿井内的气生根系这一特殊生境中的真菌开展系统分析。本研究采用靶向核糖体RNA基因的3组互补引物组，通过Illumina测序（Illumina sequencing）评估真菌多样性，并通过非编码trnH-psbA间隔区（trnH-psbA spacer）对根系进行鉴定。早期定殖的外生菌根真菌（ectomycorrhizal fungi）以伞菌目（Agaricales）、柔膜菌目（Helotiales）、盘菌目（Pezizales）及革菌目（Thelephorales）为优势类群。腐生真菌、内生真菌与植物病原菌亦有检出，但未检测到球囊霉门（Glomeromycota，丛枝菌根真菌）。真菌根系群落通常在同一样地内具有最高的相似性。真菌多样性与冬季暗区温度及距洞口距离呈负相关关系。相较于单一组引物组，联合使用3组引物组可检测到更多的真菌分类单元。本研究增进了学界对这类地下生态系统的认知，并提出未来研究可围绕限制后期外生菌根真菌与球囊霉门真菌存续的关键因素展开探索。