Researchers at the Max Planck Institute for Biology Tübingen have discovered how benign strains of Pseudomonas protect against their harmful bacterial relatives. The study, now published in Nature Ecology & Evolution, shows that the coexistence of beneficial and pathogenic Pseudomonas on Arabidopsis thaliana improves plant health, but that the exact extent depends on the genetic makeup of both the plant and the microbes. The findings could help to design natural alternatives to synthetic pesticides.