P-367 - Pathogen-induced reactive oxygen species in the rhizosphere as chemoattractants for beneficial bacteria recruitment

Reactive oxygen species (ROS) generated by respiratory burst oxidase homolog D (RBOHD) play a crucial role in suppressing pathogen colonization within the roots of Arabidopsis. However, the impact of low concentrations of ROS in the rhizosphere on microbial communities remains unclear. In this study, we demonstrate that the beneficial rhizobacterium Pseudomonas anguilliseptica exhibits markedly reduced colonization in the rhizosphere of rbohD mutants compared to wild-type plants. Strikingly, we discovered that low concentrations of ROS promoted the motility and chemotaxis of P. anguilliseptica. Moreover, in contrast to the nitrogen-fixing bacterium Ensifer sesbaniae, treatment with the pathogen Dickya solani triggered preferential recruitment of P. anguilliseptica to the rhizosphere, thereby mitigating the severity of pathogen-induced diseases. These findings illuminate a dual role for ROS during pathogen challenge: direct antimicrobial activity against invaders coupled with chemotactic signaling that enriches beneficial microbiota to suppress pathogenesis. Collectively, our work uncovers a novel chemoattractant function of rhizospheric ROS, offering insights into plant-microbe interactions with potential applications in sustainable agriculture.