Prospects and Limitations of Synthetic Antimicrobial Peptides for Fire Blight Control

Chemical control of fire blight in rosaceous plants is limited by the low number of available bactericides. Synthetic antimicrobial peptides (AMPs) are potential candidates for fire blight control, because they can be designed and produced by peptide chemistry approaches with optimized activity, toxicity and biodegradability. Libraries of 260 AMPs have been prepared including linear and cyclic peptides, 5-arylhistidine-containing sequences, cyclolipopeptides, peptidotriazoles, multivalent display structures, and peptides to be expressed in plants. Several leads from these libraries were developed and optimized against Erwinia amylovora, with minimum inhibitory concentrations in the range of 2.5 to 12.5 mu M, and minimized toxicity. Two linear undecapeptides, BP100 and BP143, have been tested for fire blight control in ex vivo and field trials, with comparable efficacy to reference antibiotics.