Arbuscular mycorrhizal fungi alleviate the pathogenic stress on the invasive weed Alternanthera philoxeroides

Abstract

Invasive plants have caused huge damages in ecosystems. Arbuscular mycorrhizal fungi (AMF) play important roles in plant growth. However, the importance of AMF in pathogenic stress on invasive plants were rarely studied. The effects of AMF (Glomus etunicatum) on the resistance to pathogenic fungus Rhizoctonia solani of an invasive plant Alternanthera philoxeroides were examined in this study. Our results showed that AMF significantly promoted stem length, spacer length, and leaf area of A. philoxeroides. The pathogen R. solani negatively impacted plant growth, including above-ground biomass and root characteristics. However, AMF inoculation mitigated these negative effects. Notably, AMF colonization rates increased significantly in the presence of pathogen. AMF significantly promoted the above-ground growth and decreased the root/shoot ratio to help resist pathogen. These findings indicate that AMF can enhance A. philoxeroides resistance to pathogenic stress, potentially contributing to its invasive success. This study provides insights into the complex interactions between invasive plants, beneficial fungi, and pathogens, which may have implications for understanding and managing plant invasions.