Fungal pathogens cause devastating crop losses worldwide, but unfortunately, new cultivars and fungicides have been only partially successful in controlling these losses, and transgenic plants expressing antifungal proteins have proved disappointing in the field. In this issue, Gao et al. show that in transgenic potato plants, expression of the alfalfa antifungal peptide “defensin”confers strong, sustained resistance to damage from the fungal pathogen Verticillium dahliae. After isolating the peptide from seeds of Medicago sativa , they cloned the gene, expressed it in potato, and showed that the transgenic plants accumulated high levels of the alfalfa defensin. The potatoes performed well in the greenhouse and, more importantly, as well as commercial fumigants in field trials, suggesting that defensin genes have important commercial potential for effective fungal control in economically important crops (see p. 1307).