Soil-borne diseases in medicinal plants: linking allelopathy and host immunity to microbiome-based interventions

The rising global demand for natural medicines has intensified the cultivation of Chinese medicinal herbs, exacerbating continuous cropping obstacles and constraining the sustainable development of Chinese medicinal materials. A defining manifestation is a severe soil-borne disease that limits long-term productivity and stable medicinal quality. Despite progress in understanding individual diseases or host species, integrative syntheses of the coupled "pathogen-environment-host" network remain limited. Here, we synthesize the current understanding of soil-borne disease development under continuous cropping and evaluate ecological management options by integrating evidence on pathogen virulence, continuous-cropping-driven edaphic shifts, host immunometabolism (the coupled reprogramming of immunity and metabolism), and microbiome-based interventions. We summarize the major soil-borne pathogens and their virulence determinants and explain how allelochemical accumulation reshapes the rhizosphere microbiome, weakens the barrier functions, and facilitates pathogen ingress. We further discuss how allelochemical stress reprograms defense hormone networks (notably salicylic acid and jasmonic acid pathways) with downstream consequences for innate immune competence. Building on these insights, we assessed microbiome-guided strategies to restore rhizosphere function, including synthetic community design, recruitment of probiotic taxa, and induction of disease-suppressive soils. By integrating microbiology, chemical ecology, and plant pathology, this review provides a conceptual framework and actionable directions for the precise and sustainable control of soil-borne diseases in Chinese medicinal herb production.