AUTHOR=Zamuner Caio Felipe Cavicchia , Marin Vítor Rodrigues , Dilarri Guilherme , Hypolito Giovane Boerner , Sass Daiane Cristina , Ferreira Henrique 

TITLE=Oregano essential oil and its main components Thymol and Carvacrol as alternatives to control citrus canker

JOURNAL=Frontiers in Agronomy

VOLUME=5

YEAR=2023

URL=https://www.frontiersin.org/journals/agronomy/articles/10.3389/fagro.2023.1148969

DOI=10.3389/fagro.2023.1148969

ISSN=2673-3218

ABSTRACT=<p>Plant Essential Oils and their constituents are well-known for their properties as antimicrobial agents and are labeled as Generally Recognized as Safe (GRAS), prompting studies around their usage in the control of food-borne microorganisms and phytopathogens. In this study, we evaluated Oregano Essential Oil (OEO), Thymol (THY) and Carvacrol (CAR) for the control of <italic>Xanthomonas citri</italic> subsp. <italic>citri</italic> (<italic>X. citri</italic>). <italic>In vitro</italic> antibacterial assays revealed that CAR and THY inhibit <italic>X. citri</italic> growth at the concentrations of 100 µg.mL<sup>-1</sup> and 114 µg.mL<sup>-1</sup>, lower than OEO (136 µg.mL<sup>-1</sup>). Bactericidal effects were observed at 400 µg.mL<sup>-1</sup> for OEO and 200 ug.mL<sup>-1</sup> for CAR and THY. Investigating potential cellular targets for the compounds showed that after 30 minutes of exposure up to 84% of the cells had their membranes disrupted, implicating the membrane as the primary target. Phytotoxicity evaluations using <italic>Lactuca sativa</italic> and <italic>Solanum lycopersicum</italic> seeds showed an acute toxic effect in all treatments above 200 µg.mL<sup>-1</sup>, except for OEO and THY in <italic>S. lycopersicum</italic> at lower concentrations. Regarding their protective effect on citrus leaves, CAR showed no effect when compared to the untreated control (0.39 and 0.50 lesions per cm<sup>2</sup>, respectively). OEO and THY were able to reduce significantly citrus canker symptoms (0.18 and 0.11 lesions per cm<sup>2</sup>, respectively). In addition, no toxic effects were observed on citrus leaves in all treatments. THY inhibits <italic>X. citri</italic> growth and the development of citrus canker lesions. These results show that THY as a viable alternative to be used in citrus canker management.</p>