RESUMEN
Pseudomonas syringae pv. actinidiae (Psa) is the pathogenic agent responsible for the bacterial canker of kiwifruit (BCK) leading to major losses in kiwifruit productions. No effective treatments and measures have yet been found to control this disease. Despite antimicrobial peptides (AMPs) having been successfully used for the control of several pathogenic bacteria, few studies have focused on the use of AMPs against Psa. In this study, the potential of six AMPs (BP100, RW-BP100, CA-M, 3.1, D4E1, and Dhvar-5) to control Psa was investigated. The minimal inhibitory and bactericidal concentrations (MIC and MBC) were determined and membrane damaging capacity was evaluated by flow cytometry analysis. Among the tested AMPs, the higher inhibitory and bactericidal capacity was observed for BP100 and CA-M with MIC of 3.4 and 3.4-6.2 µM, respectively and MBC 3.4-10 µM for both. Flow cytometry assays suggested a faster membrane permeation for peptide 3.1, in comparison with the other AMPs studied. Peptide mixtures were also tested, disclosing the high efficiency of BP100:3.1 at low concentration to reduce Psa viability. These results highlight the potential interest of AMP mixtures against Psa, and 3.1 as an antimicrobial molecule that can improve other treatments in synergic action.
Asunto(s)
Proteínas Citotóxicas Formadoras de Poros/farmacología , Pseudomonas syringae/efectos de los fármacos , Actinidia , Antibacterianos/farmacología , Péptidos Catiónicos Antimicrobianos/farmacología , Sinergismo Farmacológico , Frutas/efectos de los fármacos , Histatinas/farmacología , Oligopéptidos/farmacología , Enfermedades de las Plantas/microbiología , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Pseudomonas syringae/metabolismo , Pseudomonas syringae/patogenicidadRESUMEN
Bacterial canker of the kiwifruit caused by the etiological agent Pseudomonas syringae pv. actinidiae is the most severe disease in kiwifruit production. Since 2008 a hypervirulent Psa biovar 3 has spread rapidly worldwide. Different genomic and phenotypic approaches have been used to understand the origin of the dissemination and geographical evolution of populations associated with this pandemic. This study aimed to characterize the genetic and phenotypic diversity of 22 Psa isolates collected in different regions of Portugal between 2013 and 2017. Genotypic and phenotypic characterization was based on Multi-Locus Sequence Analysis (MLSA), motility, IAA production, Biolog GEN III, and copper sensitivity. No polymorphisms were detected for the concatenated sequence (1950 bp) of the housekeeping genes gltA, gapA, gyrB, and rpoD. Results support the analysed Portuguese Psa isolates (2013-2017) belonging to Psa3, and MLSA indicates high genetic clonality and stability of these populations. The phenotypic analysis through Biolog revealed a heterogeneous pattern in the Psa collection and its position in the Pseudomonas complex. This heterogeneity reflects a genomic diversity that may reflect distinct adaptive trends associated with the environmental conditions and widespread. The Portuguese Psa collection showed no resistance to copper. This information is relevant to kiwi producers that predominantly use Cu-treatments to control kiwifruit bacterial canker.