Reactive oxygen species in the rhizosphere orchestrate the recruitment of beneficial bacteria.

Respiratory burst oxidase homolog D (RBOHD)-dependent reactive oxygen species (ROS) in Arabidopsis are well known to suppress pathogen colonization, but their influence on beneficial microbes remains unclear. Here, we found that the beneficial rhizobacterium Pseudomonas anguilliseptica was significantly less enriched in the rhizosphere of rbohD mutants than in that of wild-type plants. Conversely, elevated rhizosphere ROS levels, either triggered by pretreatment with pathogenic Dickeya solani bacteria or caused by mutations in ROS scavenging genes (e.g., in apx1 and cat2 mutants), promoted the rhizosphere recruitment of P. anguilliseptica. This promoting effect was abolished by catalase treatment. In situ microfluidic chemotaxis assays further revealed that P. anguilliseptica exhibits a chemotactic response to low concentrations of hydrogen peroxide ( ≤ 500 nM), accompanied by upregulated expression of chemotaxis- and motility-related genes. Notably, inoculation of P. anguilliseptica effectively suppressed D. solani-induced disease symptoms, and this protective effect was attenuated by catalase treatment. Collectively, these findings reveal a previously unrecognized role of ROS in recruitment beneficial microbiota to enhance plant growth and suppress disease symptoms.