Codonopsis pilosula regulates pathogen defense mechanisms through collaboration of root volatile compounds and microbial interactions

Codonopsis pilosula responds to pathogen infection by modulating root volatile organic compounds (VOCs) and reshaping the rhizosphere microbiome. GC-IMS analysis linked root VOCs with microbial community composition, showing positive correlations with Bradyrhizobium and beneficial fungi, and negative associations with Alternaria pathogens. Representative VOCs-benzothiazole, linalool, and (E,E)-2,4-heptadienal-showed significant antifungal activity against Fusarium oxysporum. Molecular docking and qPCR analyses indicate that these compounds may interact with stress-related proteins and potentially influence autophagy-associated pathways, suggesting stress responses that could contribute to fungal growth inhibition or cell death. Although autophagy was not directly demonstrated, these findings highlight VOCs as important mediators of plant defense signaling and may support the development of eco-friendly VOC-based antifungal strategies.