Project description:<p>Soil-borne diseases, with their high incidence and frequency in monoculture systems, pose a major challenge in contemporary agricultural production. Intercropping can promote beneficial soil legacy effects, thereby effectively mitigating the occurrence and damage of soil-borne diseases. In this study, we employed an integrated approach combining 16S rRNA sequencing, ITS amplicon sequencing, and untargeted metabolomics to systematically compare the differences in soil microbial community structure and metabolite profiles between soybean-tobacco intercropping and tobacco monoculture systems. Furthermore, we elucidated the mechanisms through which these differences influence the incidence of tobacco root rot. The results showed that intercropping significantly enhanced the survival rate of tobacco plants under Fusarium.spp infection (P < 0.01). Furthermore, intercropping markedly increased soil microbial community diversity and significantly reduced the relative abundance of Fusarium (by 53.17%). Additionally, intercropping disrupted the cooperative relationships between Fusarium and other microbial taxa, leading to reduced connectivity within the interaction network and a notable decline in its ecological competitive advantage. Metabolomic analysis revealed that intercropping promoted the accumulation of antimicrobial metabolites such as indole, and indole content was significantly negatively correlated with Fusarium abundance (P < 0.05). Further integrated microbiome-metabolome analysis demonstrated that intercropping fostered a more complex microbial-metabolite interaction network, which helped suppress the recolonization of pathogenic Fusarium. In conclusion, this study provides a theoretical basis for leveraging intercropping systems to modulate the rhizosphere micro-environment and control soil-borne diseases, offering new insights for developing sustainable green control strategies.</p>