Tobacco plants are under attack from a fungal disease caused by Rhizoctonia solani. Scientists discovered that this fungus produces a protein called RsDN3377 that helps it grow and infect plants. However, tobacco plants have evolved a defense protein called NtCML19 that recognizes RsDN3377 and triggers an immune response to fight off the infection. By engineering tobacco plants to produce more NtCML19, researchers showed they could make the plants more resistant to the disease, suggesting a potential new strategy for protecting crops.