Influence of root secretions of understory Chinese herbal medicines on the characterization of inter-root microbial communities

The root exudates of Chinese medicinal herbs under the forest play a crucial regulatory role in the rhizosphere microbial community. This study systematically revealed the chemical characteristics of root exudates from Panax notoginseng, Polygonatum sibiricum, and Eutrema wasabia under the forest and their differential impact mechanisms on the rhizosphere microbial community. Research has found significant species specificity in the types and quantities of root exudates from three plants. 329, 250, and 193 differential compounds were identified in Panax notoginseng, Polygonatum sibiricum, and Eutrema wasabia, respectively. Among them, Panax notoginseng and Eutrema wasabia share 165 compounds, both of which are mainly composed of lipids and organic acids. However, the specific types and proportions vary, reflecting their unique ecological functions and pharmacological effects. Root exudates significantly regulate the structure and diversity of microbial communities, with Proteobacteria, Acidobacteria, and Basidiomycota being dominant groups. Mantel test confirmed that the main components of secretions are significantly positively correlated with the abundance and diversity of microbial communities. KEGG pathway enrichment analysis further showed that different plants adapt to the environment by activating differentiated metabolic pathways (22 enriched in Panax notoginseng, 20 enriched in Polygonatum sibiricum, and 15 enriched in Eutrema wasabia). More importantly, the microbial metabolite interaction network analysis revealed processing specificity: specific bacteria in the Panax notoginseng forest were strongly positively correlated with lipids, fungi with phenolic metabolites, while Polygonatum sibiricum and Eutrema wasabia forests showed a completely different association pattern, regulating the accumulation of key metabolites such as lipids, phenols, and oligosaccharides by reshaping the network. These findings provide key evidence for understanding the microbial driven mechanisms underlying the quality formation of medicinal plants, emphasizing the importance of optimizing root exudates management to enhance soil microbial health and promote sustainable agricultural development.