Brassica seed meal fumigation restores beneficial bacterial communities by enriching taxa with high resistance and resilience.

Purpose: Brassica seed meals (BSMs) are widely used as biofumigants to control various soil-borne plant diseases. However, the mechanism of bacterial community reconstruction following fumigation with BSMs remains poorly understood. Methods: In the present study, to decipher the mechanism of bacterial community reconstruction in fumigated soil and to understand the effect of bacterial communities in fumigated soil on rhizosphere recruitment and subsequent disease control, we investigated the bulk soil and rhizosphere bacterial communities using field experiments in soils treated with various fumigants (Brassica campestris seed meal, Brassica juncea seed meal, and the chemical fumigant dazomet) in two greenhouses subsequently used to grow tomato and cantaloupe, respectively. Results: This study revealed that bulk soil bacterial community composition changed significantly after fumigation extinction and recovery. Firmicutes and Proteobacteria, showing high resistance and resilience in the extinction and recovery processes, respectively, represented the key microorganisms for community reconstruction and rhizosphere recruitment. Moreover, nutrients supplied by BSMs, especially available phosphorus (AP), in fumigated soils determined the post-restoration changes in bacterial community composition. Additionally, BSMs showed greater potential than chemical fumigant dazomet in rebuilding beneficial bacterial communities and controlling potential soil pathogens by enriching gram-positive phyla Firmicutes and Actinobacteria and their respective affiliated genera Bacillus and Streptomyces. Conclusion: These results provide a fundamental ecological understanding of the response of soil-inhabiting microbes to fumigation and the reconstruction of soil beneficial bacterial communities after BSM fumigation. Thus, this study improves the understanding of the effects of biofumigants on soil-borne plant disease control in agriculture. [ABSTRACT FROM AUTHOR]