The rhizosphere microbiome plays a crucial role in the resistance to soilborne plant diseases. However, the principles needed to explain and predict which microbiota will be effective against soilborne pathogens are still lacking due to the complexity of the soil microbial community. We hypothesized that, independent of particular microbial strains, a high diversity is associated with, or increases the probability of, effective suppression. We tested this hypothesis by demonstrating that random combinations of rhizosphere microbial isolates, with the same bacterial diversity, had an equal impact on suppressing root diseases. The incidence of root rot was significantly reduced when soil bacterial diversity was high. We further investigated how high-diversity bacterial communities suppress root rot by constructing synthetic bacterial communities (SynComs). The results suggest that high bacterial diversity suppresses pathogens through mechanisms potentially including nutrient competition and the formation of physical barriers on the root surface. Our study highlights that high bacterial diversity is beneficial for suppressing soilborne plant diseases, offering a nonchemical and sustainable approach for crop disease management.
Bai et al. (Mon,) studied this question.