Pre-Crop Choice Shapes Nematode-Attached Bacterial Communities Associated With Reduced Pratylenchus penetrans Invasion of Barley Roots

Soil microbiomes play a crucial role in plant–parasitic nematode suppression; however, the influence of plant–soil interactions remains unclear. This study examines plant–soil feedback effects on microbiomes attached to the cuticle of Pratylenchus penetrans in winter barley. We tested whether bacterial drivers of nematode suppression remain conserved across plant hosts or exhibit host specificity. Surface-sterilised P. penetrans were baited in different soils and rhizospheres, and their attached bacterial communities were analysed. Fallow and rhizosphere microbiomes from reduced P. penetrans invasion in barley, and suppression strength varied by plant species. Only the maize and Ethiopian mustard microbiomes inhibited invasion relative to other microbiomes and to surface-sterilised nematodes. By contrast, association with the oat microbiome did not reduce P. penetrans invasion of barley roots. The suppression of P. penetrans invasion relied on the cuticle-associated bacteria, with maize showing a distinct assembly rich in Proteobacteria and Firmicutes. Suppressive cuticle-associated bacteria differed between nematodes exposed to maize-derived and Ethiopian mustard-derived rhizosphere microbiomes from the same soil. Specific bacterial genera associated with reduced invasion included Chryseobacterium, Duganella, Streptomyces, Asticcacaulis, Pseudomonas, and members of Enterobacteriaceae. These results indicate that crop rotation and cover crop choices could steer nematode-associated microbiomes toward communities that prevent root invasion.