Ectomycorrhizal fungal communities are dominated by mammalian dispersed truffle-like taxa in north-east Australian woodlands

Abstract

Mycorrhizal fungi are very diverse, including those that produce truffle-like fruiting bodies. Truffle-like fungi are hypogeous and sequestrate (produced below-ground, with an enclosed hymenophore) and rely on animal consumption, mainly by mammals, for spore dispersal. This dependence links mycophagous mammals to mycorrhizal diversity and, assuming truffle-like fungi are important components of mycorrhizal communities, to plant nutrient cycling and ecosystem health. These links are largely untested as currently little is known about mycorrhizal fungal community structure and its dependence on mycophagous mammals. We quantified the mycorrhizal fungal community in the north-east Australian woodland, including the portion interacting with ten species of mycophagous mammals. The study area is core habitat of an endangered fungal specialist marsupial, Bettongia tropica, and as such provides baseline data on mycorrhizal fungi-mammal interactions in an area with no known mammal declines. We examined the mycorrhizal fungi in root and soil samples via high-throughput sequencing and compared the observed taxa to those dispersed by mycophagous mammals at the same locations. We found that the dominant root-associating ectomycorrhizal fungal taxa (> 90% sequence abundance) included the truffle-like taxa Mesophellia, Hysterangium and Chondrogaster. These same taxa were also present in mycophagous mammalian diets, with Mesophellia often dominating. Altogether, 88% of truffle-like taxa from root samples were shared with the fungal specialist diet and 52% with diets from generalist mammals. Our data suggest that changes in mammal communities, particularly the loss of fungal specialists, could, over time, induce reductions to truffle-like fungal diversity, causing ectomycorrhizal fungal communities to shift with unknown impacts on plant and ecosystem health.