Elucidating the suppressive role of native bacterial traits against root-knot nematodes to control plant-parasitic effect in serpentine hostile rhizosphere soil

Abstract

Root-knot nematodes (RKNs) pose a major threat to natural vegetation and agricultural productivity worldwide. The plant rhizosphere harbors rich and diverse bacterial communities, however, the role of native rhizobacterial traits in plant protection against RKN parasitism remain unclear. This study investigated how rhizobacteria associated with serpentine-adapted plants suppress RKNs under extreme edaphic stress. Results showed that serpentine soil factors and RKN presence altered bacterial community assembly, and edaphic stress intensified RKN parasitic effects. Increased bacterial diversity and abundance were strongly correlated with a reduction in the abundance of RKN. Key bacterial taxa such as Pseudomonas putida, P. parafulva, P. straminea, and Burkholderia gladioli were enriched and linked with the suppression of Meloidogyne javanica and M. ethiopica. Functional pathways related to chitin degradation, chorismate metabolism, L-arginine biosynthesis, teichoic acid biosynthesis, and catechol degradation to beta-ketoadipate were significantly enriched and linked to plant protection against RKN infections and parasitic effects (**p < 0.01; *p < 0.05) in rhizosphere soils. Structural equation modeling (SEM) showed that heavy metals (HMs) and nutrients accounted for 78 % and 86 % of the variance (R² = 0.78; R² = 0.86) in rhizobacterial and RKN communities, respectively. Canonical correspondence analysis (CCA) revealed that HM stress and nutrient availability influenced rhizobacteria–RKN interactions, while pH, moisture content (MC), and electrical conductivity (EC) significantly regulated their composition and distribution. These findings highlight the ecological importance of native rhizobacteria in mitigating plant nematode parasitism and offer a sustainable strategy for managing nematode stress in challenging soil ecosystems.