Arbuscular mycorrhizal fungi promote superior root trait combinations conducive to soil nutrient acquisition by natives relative to invaders

Plant invasion is a growing issue worldwide, with exotic plants consistently dominating various ecosystems. Plant functional traits, particularly root functional traits, can reflect differences in soil nutrient acquisition, thus affecting the competition between invasive and native plants. Arbuscular mycorrhizal (AM) fungi are vital in altering plant root traits by establishing partnerships with the root system. However, it is unclear how plant root traits associated with distinct soil nutrient acquisition in competitive invasive and native plants respond to AM fungi regulation. We used the invasive Eupatorium adenophorum and native Eupatorium lindleyanum involving inoculation with (M+) or without (M−) AM fungus Glomus etunicatum in monoculture (Mono-) or mixed culture (Mix-) of the two species in a pot to examine differences in plant root traits and soil properties. The results showed that AM fungus significantly improved the root biomass, length, surface area, volume, and branching points (RBP) of invasive E. adenophorum and native E. lindleyanum. Under M+, the specific root length (SRL), branching intensity (BRI), and root nitrogen content (RNC) of invasive E. adenophorum were significantly higher than those of native E. lindleyanum, and the root mycorrhizal colonization (%AMF) and root average diameter (RAD) of native E. lindleyanum were significantly higher than those of invasive E. adenophorum in Mix- condition. These findings suggest that invasive E. adenophorum is more dependent on its roots than on the AM fungus for soil nutrient acquisition, whereas native E. lindleyanum is more dependent on the AM fungus than on its roots for soil nutrient acquisition. Meanwhile, AM fungus impacted differences in soil nutrient uptake of nitrogen (N) and phosphorus (P) by differentially enhancing root growth between invasive and native plants. In conclusion, AM fungus promoted superior root trait combinations conducive to soil nutrient acquisition by natives relative to invaders. The differences between exotic and native plants in developing root systems and investing in AM fungi to acquire soil nutrients provide references for further facilitating the formulation of effective invasion mitigation strategies.