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Antibacterial and plant defence elicitor peptides for plant disease control

Emilio Montesinos: University of Girona

<div>Synthetic peptides offer great possibilities as novel compounds to the control plant diseases. Libraries of synthetic analogs of natural peptides or <em>de novo</em> designed peptides have been prepared by solid phase chemistry and combinatorial approaches. Leads from these libraries have minimal inhibitory concentrations in the range of common antibiotics, and some have additional activity as plant defence elicitors and cell-penetrating peptides. Several of the most promising peptides had low toxicity profiles with moderate susceptibility to proteases. Antimicrobial peptides of the CECMEL11 library have been effective in greenhouse experiments and field trials, against fireblight (<em>Erwinia amylovora</em>) and bacterial blight of pear (<em>Pseudomonas syringae</em> pv. syringae), bacterial spot and canker of <em>Prunus</em> (<em>Xanthomonas arboricola</em> pv. pruni), and bacterial canker of kiwifruit (<em>P. syringe</em> pv. actinidiae), and also in the control of two diseases caused by phytoplasms, and against brown spot of pear (<em>Stemphylium vesicarium</em>). A new generation of synthetic analogs of endogenous elicitor peptides from <em>Prunus</em> (namely PEPs), lacking antimicrobial properties, were effective in protection against <em>X. arboricola</em> pv. pruni infections. The peptide BP178, a derivative from the BP100 CECMEL11 peptide, showed antibacterial and plant defence elicitation activity, and was active against <em>Xylella fastidiosa</em> subspecies. The prospects and limitations of these functional peptides in plant protection, in the scenario of emerging diseases and the current regulatory framework will be discussed.</div>