Abstract
Mycorrhizal fungi serve important functions in Australian ecosystems by forming mutualistic symbioses with plants that facilitate water and nutrient uptake. Scat analyses have shown that southern brown bandicoots (Isoodon obesulus fusciventer; 'Quenda') regularly feed on fungi, including ectomycorrhizal (ECM) species. Many of these ECM species are hypogeous and rely on mycophagous animals such as quenda to disperse their spores. We explored the tripartite relationship between a keystone Mediterranean tree, its associated mycorrhizal fungi, and a mammalian disperser. Wild-collected quenda scats were used as a mycorrhizal inoculum to grow Eucalyptus gomphocephala from seeds under glasshouse conditions. Autoclaved scats were used as a negative-control and sporocarp tissue from Pisolithus and Scleroderma ectomycorrhizal species were mixed together as a positive-control inoculum. Seedlings were harvested at 10 weeks to assess seedling growth and early mycorrhizal colonization of roots by high-throughput DNA sequencing. Quenda scat successfully introduced fungi to seedlings, shown by a 56% overlap of fungal operational taxonomic units (OTUs) detected in the scats and roots grown in fresh scat inoculum. Scat-inoculated seedlings had richer root mycorrhiza fungal assemblages and a higher proportion of mycorrhizal taxa compared to negative- and positive-controls. However, no difference in shoot or root mass in these young seedlings could be attributed to root fungi assemblages at this early growth stage, possibly reflecting that the role of mycorrhizae in these early seedlings was parasitic, rather than facilitatory. Our study has shown that spores of mycorrhizal fungi from the quenda scat inoculum can successfully germinate and colonize seedling roots after passage through the quenda gut.
