Influence of Mikania micrantha Kunth Flavonoids on Composition of Soil Microbial Community

Mikania micrantha, one of the world's most destructive invasive species, is known for causing significant ecological and economic harm. While extensive research has focused on its growth characteristics, secondary metabolites, and control measures, its chemical interactions with the environment-particularly the role of flavonoids in shaping soil microbial communities-remain underexplored. In this study, we identified and quantified ten flavonoids from M. micrantha root exudates using UPLC-MS, including Hispidulin, Isorhamnetin, and Mikanin. To examine their impact, crude flavonoid extracts were applied to soil in potted experiments, which demonstrated that these compounds significantly increased soil fungal diversity and boosted the relative abundance of arbuscular mycorrhizal fungi (AMF). Furthermore, KEGG pathway analysis revealed that flavonoid addition elevated the copy numbers of genes involved in nitrogen cycling and metabolic functions, enhancing nutrient availability and microbial activity. Additionally, crude flavonoid extracts promoted the relative abundance of beneficial soil bacteria, such as Achromobacter, as well as AMF, both of which contribute to nutrient acquisition, plant growth, and soil health. These findings indicate that M. micrantha's flavonoids can alter soil microbial community composition, thereby creating a favorable environment that reinforces its competitive edge over native plants.