In this issue, Sautter and colleagues use a new approach for improving crop resistance to fungal infections. They took advantage of a so-called “killing protein” produced by a virus that infects the fungi, which can inhibit growth of fungal strains other than the host strain. They showed that expression of a Ustilago killing protein in wheat provided resistance to smut fungi responsible for large crop yields in economically important crops like wheat, maize, and oat (see p. 446).