Bionematicides shape plant growth-promoting bacteria community in the sugarcane rhizosphere

Abstract

Monocropping can negatively affect biodiversity and promote the incidence of plant-parasitic nematodes. To mitigate these effects, bionematicides containing microorganisms have been employed as a strategy for nematode control. However, their impact on the community of plant growth-promoting bacteria (PGPB) in the rhizosphere remains poorly understood. This study aimed to evaluate the effects of different bionematicides on the PGPB community in the sugarcane rhizosphere, with Pratylenchus zeae as the target root nematode. A greenhouse experiment was conducted using six microbial formulations with nematicidal properties, containing Bacillus subtilis, Bacillus amyloliquefaciens, Pseudomonas oryzihabitans, Purpureocillium lilacinum, and Bacillus licheniformis. The PGPB community was characterized through 16S rRNA gene amplicon sequencing. Our results revealed that Bacillus and Sphingomonas were the most abundant PGPB taxa in the rhizosphere, regardless of bionematicide application. However, microbial diversity increased following inoculation with P. oryzihabitans and decreased with B. amyloliquefaciens and a multi-strain combination of P. lilacinum, B. subtilis, and B. licheniformis. Niche occupancy analysis indicated a predominance of generalist over specialist PGPB, with P. oryzihabitans favoring the recruitment of specialist taxa. Co-occurrence network analysis showed a stable number of nodes across treatments, while microbial interactions (edges) were highest in the P. oryzihabitans treatment. These findings suggest that bionematicides modulate PGPB diversity and interactions in the sugarcane rhizosphere, with P. oryzihabitans playing a central role in enhancing microbial specialization and network complexity.