Successive soybean plantings reshape soil microbiomes to suppress cyst nematode

Repeated planting of soybean in soil infested with soybean cyst nematode can build a soil community that suppresses the pest, according to a controlled-environment study published in Environmental Microbiome. Over successive cycles, SCN egg densities fell significantly and stabilized at low levels in later cycles, a decline the authors link to coordinated, compartment-specific microbial succession rather than to any single control agent.

All three compartments showed substantial restructuring across planting cycles, with the rhizosphere showing the greatest differentiation. Bacterial alpha diversity was negatively correlated with SCN egg densities, while fungal diversity showed positive correlations. Core microbiome analysis found no bacterial taxa consistently shared across compartments and cycles, but several core fungal taxa persisted throughout the experiment. The authors note that these are association patterns from a controlled setting, not demonstrations of causal mechanisms for individual taxa.

Differential abundance analyses revealed compartment-specific functional shifts over time. Early planting cycles were characterized by higher abundance of taxa previously reported in association with plant nutrient acquisition or pathogenicity, including Bradyrhizobium, Microlunatus, Setophoma, Ustilago, Fusarium, Dactylonectria, and members of Nectriaceae. Later cycles showed enrichment of taxa with putative antagonistic activity, such as Ohtaekwangia, Streptomyces, Pseudomonas, and members of Bacillales. Association analyses reinforced this temporal pattern: microbial taxa positively correlated with SCN egg density were enriched in early cycles and declined over time, whereas negatively correlated taxa accumulated in later cycles, with consistent dynamics across compartments.

Culture-based screening identified several potential nematicidal bacteria, and one strain, Bacillus sp. (B34), consistently suppressed SCN in susceptible soybean under the study’s conditions. The authors conclude that successive soybean monoculture under SCN pressure can drive the formation of SCN-suppressive soils through a shift from early-cycle communities enriched in nutrient-acquisition- or pathogenicity-associated taxa to later-cycle communities enriched in microbes with antagonistic potential. They argue that the findings highlight the roles of host- and nematode-associated microbiome assembly and spatiotemporal dynamics in natural disease suppression, and they position the work as supporting microbiome-based strategies for sustainable SCN management. SCN is one of the most destructive soybean pathogens worldwide, and current management relies on a limited set of resistant varieties, crop rotation, and chemical nematicides that face constraints from breakdown of host resistance and environmental concerns. Because the experiment was conducted under controlled conditions with microbiome transfer between cycles, the authors frame the results as evidence of a process that can be established experimentally, with field-scale application remaining a direction supported by, but not demonstrated in, this study.

Subject of Research: Microbiome succession in soybean rhizosphere soils that suppresses soybean cyst nematode

Article Title: Temporal microbiome succession across plant-nematode niches drives soybean cyst nematode suppression

Article References: Yin, C., & Lahr, N. (2026). Temporal microbiome succession across plant-nematode niches drives soybean cyst nematode suppression. Environmental Microbiome. https://doi.org/10.1186/s40793-026-00972-x

Image Credits: AI Generated

DOI: 10.1186/s40793-026-00972-x

Keywords: soybean cyst nematode, soil microbiome, rhizosphere, disease-suppressive soils, microbial succession, Bacillus, Streptomyces, biological control, soybean, plant pathology, root endosphere, nematicidal bacteria