Effects of Arbuscular Mycorrhizal Fungi on the Growth and Competitive Ability of Solanum rostratum, an Invasive Plant

Solanum rostratum is an invasive plant species that poses a serious threat to native ecosystems. In this study, we investigated S. rostratum populations in saline-alkali regions of western Jilin Province to characterize root-associated arbuscular mycorrhizal (AM) fungal diversity and evaluate the effects of AM fungi on plant growth and competitive ability. The results showed that S. rostratum roots were widely colonized by AM fungi, indicating abundant AM fungal resources in its rhizosphere. High-throughput sequencing identified 45 AM fungal species belonging to 13 genera, with Glomus as the dominant genus. A compartmented mesh pot experiment further demonstrated that AM fungal inoculation significantly enhanced the growth and photosynthetic performance of S. rostratum, particularly under saline-alkali soil conditions. When AM fungi were inoculated only in the compartment containing the native plant Setaria viridis, AM fungal colonization was also detected in S. rostratum roots, indicating hyphal connections between neighboring plants through the mesh barrier. Stable isotope analysis further revealed that AM fungi facilitated nitrogen acquisition by S. rostratum and increased 15N transfer from neighboring S. viridis under common mycorrhizal networks. These findings suggest that abundant AM fungal resources in the rhizosphere contribute to the growth advantage of S. rostratum. By enhancing nutrient acquisition and potentially facilitating nitrogen transfer through mycorrhizal networks, AM fungi may strengthen the competitive ability of this invasive plant under saline-alkali conditions.