Changes of rhizosphere microbiome and metabolites in Meloidogyne incognita infested soil

Purpose Microorganisms and their metabolites suppress plant parasitic nematodes. The activity and biocontrol efficiency of antagonistic microorganisms is affected by microbial interactions. Here, the changes of rhizosphere metabolome and microbiome in Meloidogyne incognita infested soil are analysed. The differences in rhizosphere microbial community and interactions, functional genes, and metabolites of soils high or low-infested with M. incognita were compared. The keystone microorganisms and nematicidal metabolites were investigated in order to find new biocontrol agents. Methods Microbial composition and functional genes were explored using metagenomics. Abundances of various metabolites were analysed via metabolomics. Microorganisms were isolated from soil, the enzyme activity was determined. Nematicidal activities of microbes and metabolites were detected. Results Rhizosphere microbial composition, function, network, and metabolites differed in high and low-infested soils. Abundances of nematicidal microorganisms and metabolites, and extracellular enzymes genes in low-infested soil were higher than in high-infested soil. The network complexity of high-infested soil decreased compared to low-infested soil network. The contents of thirty-five metabolites in the low-infested soil were higher than in the high-infested soil. The acetophenone showed high nematicidal and repellent activities against Meloidogyne incognita. Abundance of Bacillus was positively correlated with content of acetophenone. Nematicidal microbial isolates produced protease, chitinase, and lipase. Bacillus amyloliquefaciens W1 produced acetophenone and killed 98.8% of Meloidogyne incognita second-stage juveniles within 24 hours. Conclusion The composition, network structure, metabolites, and functions of rhizosphere microbiota differed in high and low-infested soils. Bacillus amyloliquefacens W1 produced acetophenone that killed Meloidogyne incognita juveniles. Acetophenone was identified as an effective nematicide.

Automated summary

This study analyzed the differences in rhizosphere microbiome and metabolome in soils infested with Meloidogyne incognita. It identified key microorganisms and nematicidal metabolites, including acetophenone, which showed high nematicidal activity. Bacillus amyloliquefacens W1 produced acetophenone and effectively killed Meloidogyne incognita juveniles. This research provides new insights into biological control agents for plant parasitic nematodes.