Abstract
The invasive plant Sphagneticola trilobata (Asteraceae), known for its rapid growth and strong adaptability, has spread widely across tropical and subtropical regions worldwide, posing a serious threat to local plant diversity. Traditional weed control approaches have limited effectiveness, and the overuse of chemical herbicides such as glyphosate not only leads to resistance but also harms the environment. This study elucidated the important roles of jasmonic acid (JA) and arbuscular mycorrhizal fungi (AMF) in jointly promoting the herbicide resistance of S. trilobata. Firstly, the herbicide tolerance of S. trilobata was tested. Then, a field experiment was conducted to test the relation between AMF colonization and herbicide resistance in S. trilobata by high-throughput sequencing, and the metabolomics analysis was conducted to test the secondary metabolite difference by AMF colonization. Lastly, a greenhouse experiment was conducted to assess the synergistic effects of JA and AMF on S. trilobata's herbicide resistance. Results showed that invasive S. trilobata has stronger glyphosate tolerance than its native congener. The field experiment showed that glyphosate treatment significantly increased the AMF colonization in S. trilobata and altered the composition of the rhizosphere AMF community. Metabolomics analysis revealed that AMF colonization upregulates the expression of stress-related metabolites, especially JA content. The greenhouse experiment further validated that both AMF colonization and JA application could enhance the stem and root length and plant biomass. Under glyphosate application, AMF and JA enhanced plant growth and relative chlorophyll content, while reducing relative flavonol and anthocyanin contents. Furthermore, the interaction of AMF and JA treatments led to a significant synergistic effect in plant growth and resistance to glyphosate. Our findings emphasize the necessity to simultaneously consider eliminating the promoting effects of JA and AMF on the herbicide resistance when implementing chemical control management strategies for the control of S. trilobata. This study provides new theoretical bases and sustainable control strategies for invasive plant management, as well as important references for research on plant-microbe interactions and stress resistance mechanisms.