Arbuscular mycorrhizal fungi improve the competitive advantage of a native plant relative to a congeneric invasive plant in growth and nutrition

Plant invasions severely threaten natural ecosystems, and invasive plants often outcompete native plants across various ecosystems. Arbuscular mycorrhizal (AM) fungi, serving as beneficial microorganisms for host plants, can greatly influence the competitive outcomes of invasive plants against native plants. However, it remains unclear how AM fungi alter the competitive balance between native and invasive species. A competitive experiment was conducted using an invasive Eupatorium adenophorum paired with a native congener Eupatorium lindleyanum. Specifically, both species were inoculated with (M+) or without (M−) the fungus Glomus etunicatum under intraspecific (Intra‐) and interspecific (Inter‐) competition. Plant traits were measured and analyzed regarding the growth and nutrition of both species. The results exhibited that the AM fungus significantly increased the height, diameter, biomass, C, N, and P acquisition of both the invasive E. adenophorum and the native E. lindleyanum. The root mycorrhizal colonization and the mycorrhizal dependency of native E. lindleyanum were greater than those of invasive E. adenophorum. Under M+, the Inter‐competition inhibited the growth and nutrition of invasive E. adenophorum compared to the Intra‐ competition. Further, native E. lindleyanum exhibited higher competitiveness than invasive E. adenophorum in growth and nutrition. Meanwhile, the AM fungus significantly improved the competitiveness of native E. lindleyanum over invasive E. adenophorum. In conclusion, AM fungus improved the competitive advantage of native E. lindleyanum over invasive E. adenophorum in growth and nutrition, potentially contributing to native species competitively resisting the invasion of exotic species. These findings emphasize the importance of AM fungi in helping native plants resist the invasion of exotic plants and further contribute to understanding plant invasion prevention mechanisms. Mutualistic interactions with AM fungi greatly affect the outcome of invasive plants competing against native plants. We examined the effects of AM fungi on the competition between invasive plants and congeneric native plants under intra‐ and interspecific competition. The results indicate that AM fungi significantly improved the competitive advantage of native plants over congeneric exotic plants in growth and nutrition, which contributed to native plants competitively resisting exotic plants.