ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Pathogen Interactions
This article is part of the Research TopicProtecting Crops From Pests and Diseases with New Advancements in Bioprotectants and BiostimulantsView all 10 articles
Antibacterial activity of Myrtus communis leaf extract against three pathogenic Xylella fastidiosa subspecies
Provisionally accepted
Giuseppe Incampo1
MARWA MOUROU1
Davide Cornacchia1Vito Montilon1
Graziana Difonzo2
PAOLA MONTORO3
Francesco Caponio2
Francesco Faretra1
Franco Nigro1*
Stefania Pollastro1- 1Section of Plant Pathology, Department of Soil, Plant, and Food Sciences, Faculty of Agricultural Science, University of Bari Aldo Moro, Bari, Italy
- 2Universita degli Studi di Bari Aldo Moro Dipartimento di Scienze del Suolo della Pianta e degli Alimenti, Bari, Italy
- 3Universita degli Studi di Salerno Dipartimento di Farmacia, Fisciano, Italy
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The limited availability of sustainable strategies for managing Xylella fastidiosa (Xf) underscores the urgent need for innovative and practical antimicrobial solutions. In this study, an extract from the leaves of Myrtus communis (MC) biotype "Tarantino", known for its antibacterial properties, was evaluated in vitro using well diffusion and broth dilution assays against X. fastidiosa subsp. pauca (Xfp), multiplex (Xfm), and fastidiosa (Xff), all of which have been reported in Europe and in the Apulia region. Prior to biological testing, the MC leaf extract (MCLE) underwent chemical characterization via LC-Q-Exactive-Orbitrap/MS and LC-Q-Exactive-Orbitrap/MS/MS. Metabolite profiling revealed the presence of several phenolic acids, flavonol derivatives, and ellagitannins. In the in vitro assays, MCLE exhibited clear inhibition zones against all three Xf subspecies, with diameters ranging from 4.8 to 22.6 mm compared to the control. Additionally, in broth cultures, a 1:5 dilution of MCLE significantly inhibited bacterial growth, resulting in 65%, 86%, and 66% inhibition for Xfp, Xfm, and Xff, respectively. For in planta assays, symptom severity on the canopy of Nicotiana benthamiana was notably reduced in plants treated with MCLE compared to those inoculated with Xf alone. Quantitative real-time PCR confirmed the efficacy of MCLE: untreated, inoculated plants exhibited significantly lower Cq values (F = 120; p < 0.001), indicating higher bacterial loads compared to MCLE-treated plants. Overall, this study highlights the potential of MC-based formulations as promising, eco-friendly tools for the management of Xf-related diseases, meriting further validation under field conditions.
Keywords: Xylella-subspecies, biocontrol, qPCR, Plant-extract, Nicotiana benthamiana
Received: 08 Sep 2025; Accepted: 06 Nov 2025.
Copyright: © 2025 Incampo, MOUROU, Cornacchia, Montilon, Difonzo, MONTORO, Caponio, Faretra, Nigro and Pollastro. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Franco Nigro, franco.nigro@uniba.it
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