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

Author(s)

Zamuner, Caio Felipe Cavicchia ; Marin, Vitor Rodrigues ; Dilarri, Guilherme ; Hypolito, Giovane Boerner ; Sass, Daiane Cristina ; Ferreira, Henrique

• Document type: Journal article
• Source: FRONTIERS IN AGRONOMY; v. 5, p. 11-pg., 2023-03-31.

Abstract

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 Xanthomonas citri subsp. citri (X. citri). In vitro antibacterial assays revealed that CAR and THY inhibit X. citri growth at the concentrations of 100 mu g.mL(-1) and 114 mu g.mL(-1), lower than OEO (136 mu g.mL(-1)). Bactericidal effects were observed at 400 mu g.mL(-1) for OEO and 200 ug.mL(-1) 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 Lactuca sativa and Solanum lycopersicum seeds showed an acute toxic effect in all treatments above 200 mu g.mL(-1), except for OEO and THY in S. lycopersicum 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(2), respectively). OEO and THY were able to reduce significantly citrus canker symptoms (0.18 and 0.11 lesions per cm(2), respectively). In addition, no toxic effects were observed on citrus leaves in all treatments. THY inhibits X. citri growth and the development of citrus canker lesions. These results show that THY as a viable alternative to be used in citrus canker management. (AU)

• FAPESP's process: 18/21164-5 - Xanthomonas citri subsp. citri citrus canker in São Paulo. molecular epidemiology and biocontrol potential of bacteriophages and their depolymerases
• Grantee: Henrique Ferreira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/50454-9 - Xanthomonas citri subs. citri, causal agent of Citrus canker: molecular epidemiology and assessment of lytic bacteriophage as Biocontrol agents
• Grantee: Henrique Ferreira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 21/10839-4 - Sustainable citriculture through controlled release of antibacterial compounds from microgel-based formulations
• Grantee: Henrique Ferreira
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 17/09233-9 - Evaluation of the anti-Xanthomonas potential action of hybrid compounds of pirazinamide-chalcone
• Grantee: Caio Felipe Cavicchia Zamunér
• Support Opportunities: Scholarships in Brazil - Master