Prosystemin-antimicrobial-peptide fusion reduces tomato late blight lesion expansion

Antimicrobial peptides offer a new method for controlling pathogens, however, many promising peptides are too small for direct production in plants. A protein delivery system was developed based on a proteolytic mechanism used by Solanaceous plants to produce the very small (18 amino acid) signaling peptide systemin from the polypeptide prosystemin. Fusion of the gene encoding the 23 kDa protein prosystemin with the antimicrobial peptide (pep11) sequence, replacing the systemin sequence, allowed for expression in transgenic tomato plants. Six days after inoculation with the late blight pathogen Phytophthora infestans, detached leaflets of transgenic tomato (Rutgers) exhibited a reduction in lesion size of at least 50 percent.