Siderophore-producing Bacillus and free-living nematodes are associated with soil suppressiveness to banana root-knot nematodes

The control of soil-borne diseases is crucial for ensuring global food security. Here, we investigate the impact of the root-knot nematode (Meloidogyne) on banana continuous cropping over a period of 11 years. The results show significant root infestation initially, but disease incidence declined markedly from the 7th cropping year onwards. Soil community profiling revealed that this intriguing onset of nematode suppressiveness was associated with changes in free-living nematode populations and rhizosphere microbiome composition. Rhizosphere microbiome analyses and strain isolation pinpointed Bacillus velezensis as a keystone taxon in soil suppressiveness to Meloidogyne. Genomics, metabolomics and bioassays validated the suppressive effects of B. velezensis against Meloidogyne and identified the siderophore bacillibactin as key metabolite with repellent and nematicidal activities. By integrating long-term field studies with multi-omics approaches, this study uncovered co-occurring increases in specific rhizobacterial genera and free-living nematodes associated with reduced root-parasitic nematode populations, offering valuable insights for sustainable agriculture. Continuous monoculture of banana can result in proliferation of parasitic nematodes. Here the authors show that in the long term, soil can become suppressive to disease and this is associated with enrichment of free-living nematodes and Bacillus bacteria.