Induction of conidial traps in the nematode-trapping fungus <i>Drechslerella dactyloides</i> by soil microbes

Predatory nematode-trapping fungi are important microbial antagonists of nematodes and can be developed into biocontrol agents. However, microbial biocontrol agents often suffer from inconsistent efficacy, primarily due to biotic and abiotic stresses in the rhizosphere soil. <i>Drechslerella dactyloides</i>, a nematode-trapping fungus, produces conidial traps in soil, serving as a survival strategy to overcome these stresses. In this study, we optimized soil suspensions to efficiently induce the formation of conidial traps. We found that bacteria in the soil directly trigger this formation. Metagenomic sequencing revealed bacterial enrichment during optimization, and we isolated and purified these bacteria with inducible activity. Our research deepens the understanding of this survival strategy of nematode-trapping fungi in nature, laying the foundation for enhancing the effectiveness of nematode biocontrol using this mechanism.