Two studies published in the journal Science by researchers at the Max Planck Institute for Plant Breeding Research in Cologne, Germany in collaboration with colleagues in China have discovered natural cellular molecules that drive critical plant immune responses. These compounds have all the hallmarks of being small messengers tailored by plants to turn on key defense-control hubs. Harnessing these insights may allow scientists and plant breeders to design molecules that make plants, including many important crop species, more resistant to disease.