Plants can distinguish between closely related beneficial bacterial strains and respond differently depending on the dose they receive. Researchers primed melon (Cucumis melo) seeds with two Bacillus strains and found that while both ultimately enhanced stress resilience, they triggered distinct developmental, metabolic, and defense programs. The work reveals that plants do not merely respond to microbial presence but actively interpret microbial identity and inoculum concentration, translating these cues into tailored physiological outcomes.