Efficacy of synthetic antimicrobial peptides against Liberibacter crescens and Xylella fastidiosa

Abstract

Xylella fastidiosa and Candidatus Liberibacter are two highly widespread phytopathogens throughout the world that cause multiple diseases having a huge economic impact on agriculture. Although multiple studies aiming to controll these pathogens, no therapeutic solutions have been found for its reduction or suppression in infected plants. Antimicrobial peptides were identified as possible candidates of treating and preventing diseases caused by these pathogens because of their low cytotoxicity and wide range of antibacterial activity against a variety of phytopathogens. Antibacterial, bactericidal and viability assessment allow to identify AMP with high antibacterial activity against Liberibacter crescens. BP5, BP3, BP24 and BP31 are among AMPs that exhibited strong antibacterial activity against Liberibacter crescens, with MIC values in the range of 6.25-50 µM. BP5 has the overall highest antibacterial activity and has been selected to be tested in planta for the control of Candidatus Liberibacter in citrus plants. In parallel, a combined peptide treatment strategy (preventive and curative) confirmed that BP2 controls the growth of Xylella fastidiosa subsp. pauca in Nicotiana benthamiana plants, 24 days after pathogen inoculation