Broccoli Biofumigation Reshapes the Rhizosphere Bacterial Community to Suppress Fusarium oxysporum and Reduce Potato Fusarium Wilt

Biofumigation is increasingly recognized as an effective strategy for managing soilborne diseases. However, the understanding of the mechanisms of biofumigation has mostly focused on its direct inhibitory effects on plant pathogens, while the rhizosphere microbe-mediated effects induced by biofumigation remain unclear. Here, we investigated the effects of broccoli (Brassica oleracea var. italica) biofumigation on potato Fusarium wilt caused by Fusarium oxysporum and elucidated the changes in rhizosphere bacterial assemblage under biofumigation. Results showed that biofumigation significantly reduced disease incidence and increased tuber yield. In vitro assays revealed a strong direct inhibition of F. oxysporum by broccoli biofumigation, but the inhibition rate decreased from 99.78% on the first day to 76.27% on the seventh day. High-throughput sequencing and culture-based analyses demonstrated that biofumigation significantly shifted bacterial community assemblage in potato rhizosphere, enriching antagonistic taxa against F. oxysporum. Functional prediction suggested that biofumigation enriched bacteria associated with nitrogen consumption and methylotrophy. The changes in the rhizosphere bacterial community showed significant correlations with the incidence and severity of Fusarium wilt, indicating that biofumigation indirectly enhanced crop resistance to plant pathogens by altering the rhizosphere microbial community. These findings extend the current understanding of biofumigation beyond direct chemical toxicity and classical antibiosis and highlight its potential as an ecological strategy that harnesses the plant-associated microbiome for disease management.