AUTHOR=Allen Michael F. , Shulman Hannah , Rundel Philip W. , Harmon Thomas C. , Aronson Emma L. 

TITLE=Leaf-cutter ants – mycorrhizal fungi: observations and research questions from an unexpected mutualism

JOURNAL=Frontiers in Fungal Biology

VOLUME=Volume 4 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/fungal-biology/articles/10.3389/ffunb.2023.1241916

DOI=10.3389/ffunb.2023.1241916

ISSN=2673-6128

ABSTRACT=Leaf-cutter ants are widely distributed and alter the physical and biotic architecture, both above-and belowground. In neotropical rainforests, they create above-and belowground disturbance gaps that facilitate oxygen and carbon dioxide exchange. Within the hyperdiverse neotropical rainforests, arbuscular mycorrhizal fungi occupy nearly all of the forest floor. Nearly every cubic centimeter of soil contains a network of hyphae of Glomeromycotina, fungi that form arbuscular mycorrhizae. Our broad question is how can alternative mycorrhizae establish, especially ectomycorrhizae, which are essential for the survival of some plant species? Specifically, is there an ant-mycorrhizal fungus interaction that facilitates that establishment in these hyperdiverse ecosystems?In a lowland Costa Rican rainforest, nests of the leaf-cutter ant Atta cephalotes cover approximately 1.2% of the land surface broadly scattered throughout the forest. Upon sequencing soil organisms, we found inoculum of many AM fungi in the nests, but these also contained inoculum of ectomycorrhizal, orchid mycorrhizal, and ericoid mycorrhizal fungi, including Scleroderma sinnamariense, a fungus critical to Gnetum leyboldii, an obligate ectomycorrhizal plant.When nests were abandoned, new root growth into the nest offered opportunities for new mycorrhizal associations to emerge. Thus, the patches created by leaf-cutter ants appear to be crucial sites for the establishment and survival of shifting mycorrhizal plant-fungal associations facilitating the high diversity of these communities. Better understanding of the interactions of organisms, including cross-kingdom, ant-mycorrhizal fungal interactions, would improve our understanding of how these ecosystems might tolerate environmental change.