Microbiol Res. 2026 Aug 4;312:128662. doi: 10.1016/j.micres.2026.128662. Online ahead of print.

ABSTRACT

Root-knot nematodes (RKNs) pose a severe threat to global agricultural production, highlighting the urgent need for effective biocontrol agents. However, the mechanisms by which biocontrol agents suppress RKNs in complex soil environments remain poorly understood, which hinders the development and practical application of these agents. In the present study, the application of Paenibacillus polymyxa KM2501-1 significantly reduced RKN disease, with a control efficacy of 69.89%. Metabolomics analysis revealed that the biocontrol agent P. polymyxa altered the composition of tomato root exudates, leading to the identification of a key fatty acyl metabolite 8-methylnon-6-enoic acid. Specifically, P. polymyxa increased the abundance of 8-methylnon-6-enoic acid, which exhibited repellent activity against RKNs in vitro and suppressed RKN infection in situ. Metagenomic analysis further demonstrated that P. polymyxa reshaped the tomato rhizosphere microbial community and promoted the enrichment of Pseudomonas putida, particularly its representative strains PR035 and PR036. Both strains exhibited significant biocontrol efficacy against Meloidogyne incognita. A significant positive correlation was observed between the levels of key metabolite 8-methylnon-6-enoic acid and the abundance of P. putida, and their combined application exhibited effective control against M. incognita. Overall, this study demonstrates that the suppression of RKNs by P. polymyxa is associated with triggering the exudation of fatty acyl metabolites from tomato roots and enriching rhizosphere Pseudomonas populations. These findings provide valuable insights into the interplay between root metabolites and the rhizosphere microbiome in mediating synergistic plant disease control, offering a theoretical basis for the development of next-generation microbial nematicides.

PMID:42556262 | DOI:10.1016/j.micres.2026.128662