Microbial interactions mediate the fairy ring type effects on alpine meadow plant communities on the Tibetan plateau

The Fairy ring (FR) is a circular formation created by the mycelium of the FR fungus during its dynamic proliferation in the soil. FRs were categorized into three types based on their varying effects on adjacent plants. Type I FRs (T1) cause extensive damage with wilting and necrosis, Type II FRs (T2) promote growth with dark-green zones, and Type III FRs (T3) feature fruiting bodies with minimal impact on vegetation. T2 FR often display conspicuous growth-promoting zones and thus are studied more frequently than other types. Here we compare three FR types-Agrocybe sp. (T1), Agaricus campestris (T2), and Clitocybe sp. (T3)-across zones (ON (beneath the fruiting body)/IN (20 cm inward from the ON zone) /OUT (20 cm outward from the ON zone) and depths (0-10/10-20 cm) in Tibetan alpine meadows using 16 S and ITS amplicon sequencing. We infer putative microbe-fungus associations from diversity patterns, differential abundances, and co-occurrence analyses. Our research revealed that bacterial diversity was minimal in the ON zones; in contrast, fungal diversity was maximal, which may be attributable to the selection and interspecific competition among FR fungi. Taxa enriched in ON zones differed among FR types: T1 exhibited enrichment of Nitrospiria (nitrification) and Phycisphaerae (organic matter decomposition); T2 demonstrated enrichment of Actinobacteria and Proteobacteria, correlating with plant-growth enhancement; T3 displayed diminished recruitment, consistent with negligible vegetation influence. Cross-kingdom co-occurrence networks demonstrated increased microbial collaboration in ON zones, especially in surface soils for T1/T3 and in subsurface layers for T2. Different types of FR fungi exert varying effects on soil microorganisms at different depths. This study provides comparative data on three types of fairy rings and their associated soil microorganisms, offering insights into elucidating the potential mechanisms of fungal-bacterial-plant interactions. However, further validation through metabolomics and controlled experiments is still required.