From Roots to Depths: Unveiling Functional Traits and Diversity of Arbuscular Mycorrhizal Fungi in Agricultural Top- vs. Subsoil

Aim: Investigate the functional diversity of top- and subsoil arbuscular mycorrhizal fungi (AMF) communities as well as specific functional traits regarding nutrient mobilization.Method: In the first experiment, five plant species with distinct functional traits were grown in top- and subsoil cores in a mesocosm experiment. Roots AMF communities’ composition was analyzed by DNA amplicon sequencing of the ITS rRNA gene. In the second experiment, we used 15N and 33P isotope tracers to test the ability of selected distinct AMF communities to stimulate nutrient mobilization from organic matter.Results: AMF richness is consistently greater in topsoil regardless of plant species (p < 0.001). Both AMF taxonomic and phylogenetic beta diversity show more diversity among subsoil communities than topsoil communities. Furthermore, subsoil AMF communities are hypothesized to be more capable of stimulating N and P mobilization from organic matter than topsoil communities.Conclusion: These results suggest that AMF communities’ composition is shaped by both plant species and soil depths. Despite topsoil AMF communities supporting greater richness, subsoil communities display greater taxonomic and phylogenetic diversity.