Transgenic potatoes expressing a novel cationic peptide are resistant to late blight and pink rot.

Potato is the world's largest non-cereal crop. Potato late blight is a pandemic, foliar wasting potato disease caused by Phytophthora infestans, which has become highly virulent, fungicide resistant, and widely disseminated. Similarly, fungicide resistant isolates of Phytophthora erythroseptica, which causes pink rot, have also become an economic scourge of potato tubers. Thus, an alternate, cost effective strategy for disease control has become an international imperative. Here we describe a strategy for engineering potato plants exhibiting strong protection against these exceptionally virulent pathogens without deleterious effects on plant yield or vigor. The small, naturally occurring antimicrobial cationic peptide, temporin A, was N-terminally modified (MsrA3) and expressed in potato plants. MsrA3 conveyed strong resistance to late blight and pink rot phytopathogens in addition to the bacterial pathogen Erwinia carotovora. Transgenic tubers remained disease-free during storage for more than 2 years. These results provide a timely, sustainable, effective, and environmentally friendly means of control of potato diseases while simultaneously preventing storage losses.