Pseudomonadaceae Promotes Tobacco Defense Against Pathogen Invasion via Root Exudate Reprogramming.

Microbial pathogens pose a serious challenge to food security under climate change. Microbiomes can filter out incoming pathogens. However, the specific microbial taxa and mechanisms that indicate the response of the microbiome and plant health to the invasion of pathogens remain largely unknown. Here, we combine multiple field surveys and experiments with DNA and RNA sequencing using tobacco (Nicotiana tabacum) and the bacterial wilt pathogen Ralstonia solanacearum as the model system, and f ind that Pseudomonadaceae constitute an important root-associated component against pathogen invasions. Based on this finding, we develop synthetic microbial consortia, which support plant health by establishing protective microbial barriers and systemically reprogramming root immunity and metabolism. Targeted metabolite profiling further identifies vanillin as a candidate bioactive component of SynCom-induced root exudates, with its concentration increasing by approximately 240% under SynCom inoculation. Exogenous vanillin inhibits the growth and motility of R. solanacearum and also suppresses several other soilborne pathogens. Together, our work establishes the root microbiome as an important component of plant immune defense and highlights microbiome inoculation as a potential tool to enhance crop resistance against increasing pathogen pressures under climate change.