Predator-driven microbial feedback loops promote plant health.

Area of Science:

• Microbial ecology
• Soil science
• Plant pathology

Background:

• Top-down trophic interactions significantly influence microbiome dynamics, but their impact on pathogen control is not well understood.
• Predicting the outcomes of these interactions and their role in disease suppression remains a challenge.

Purpose of the Study:

• To investigate whether microbivorous nematodes can reorganize soil microbiomes to effectively suppress soilborne plant diseases.
• To elucidate the mechanisms by which nematodes mediate microbiome structure and function for enhanced disease resistance.

Main Methods:

• Combined synthetic bacterial communities, field studies, and microcosm assays to assess nematode effects on microbiome stability and disease suppression.
• Analyzed bacterial community composition, metabolic versatility, and inter-species interactions under varying conditions, including pathogen invasion.

Main Results:

• Nematode presence led to stable microbiome suppression of pathogens, contrasting with the collapse of microbe-only communities.
• Nematode predation selectively depleted certain bacterial taxa while enriching metabolically versatile Proteobacteria, fostering complementary resource use and increasing antagonistic potential.
• A four-component feedback loop involving nematodes, pathogens, and bacteria explained the emergent disease suppression.

Conclusions:

• Animal-mediated interactions, specifically by nematodes, represent a crucial pathway for microbiome assembly that bolsters resistance to pathogen invasion.
• These findings offer a trophically informed framework for developing stable, disease-suppressive microbiomes in agricultural settings.