Integrated metabolomics and metagenomics uncover pathogenic mechanisms of Fusarium wilt and faba bean defense responses.

Fusarium wilt diseases pose a huge threat to faba bean (Vicia faba L.) production globally, with significant outbreaks in Chongqing, China. Symptomatic plants showed wilting leaves and rotten roots, ultimately perishing in the advanced stage. Morphological features, multilocus phylogenetic analyses, and pathogenicity tests demonstrated that the primary causal agent was Fusarium oxysporum. Untargeted metabolomics of faba beans revealed substantial metabolic differences in the infected faba bean roots. Plants responded to fungal biotic stress by reprogramming key metabolic pathways, including alanine, aspartate, and glutamate metabolism, the citrate cycle, arginine biosynthesis, and jasmonic acid metabolism, which collectively underscore activated defense responses. Metagenome sequencing showed that Fusarium wilt significantly reshaped the structure of the rhizosphere microbiota and affected the abundance of genes encoding element cycling in soil. This work elucidates the pathogenic mechanisms of F. oxysporum by integrating pathogen identification, host metabolism, and microbiome ecology. Our findings offer biomarkers for disease diagnosis and targets for biocontrol, advancing sustainable management of Fusarium wilt diseases in legumes.