# Cinnamon Bark Essential Oil as a Natural Plant Protection Agent: Chemical Profile, Antimicrobial Activity, and Defence Induction

## TL;DR

Cinnamon bark essential oil shows strong antimicrobial properties and can boost plant defenses, making it a promising natural crop protection agent.

## Contribution

This study is the first to systematically evaluate the antimicrobial and plant defense-inducing properties of Cinnamomum verum essential oil.

## Key findings

- Cinnamon bark essential oil (CBO) showed broad-spectrum antimicrobial activity against various phytopathogens.
- CBO significantly reduced bacterial metabolic activity and induced plant defense responses in wheat leaves.
- The oil's main components include cinnamaldehyde, linalool, and eucalyptol.

## Abstract

Ceylon cinnamon (Cinnamomum verum J. Presl) bark essential oil (CBO) represents a promising source of natural bioactive compounds for biological plant protection. For the first time, the antibacterial and antifungal activity of CBO was systematically evaluated against a curated panel of phytopathogenic strains (IOR collection), revealing broad-spectrum efficacy across both bacteria and filamentous pathogens. This study evaluated its chemical composition, antimicrobial activity against phytopathogens, effects on bacterial metabolic activity, and its ability to induce plant defence responses. CBO was dominated by cinnamaldehyde, linalool, and eucalyptol. The oil exhibited strong antibacterial activity against Dickeya dadantii, Pectobacterium carotovorum, Pseudomonas syringae, and Xanthomonas hortorum as well as antifungal activity against Fusarium graminearum, F. culmorum, Rhizoctonia solani and Phytophthora cinnamomi. Metabolic assays revealed a marked reduction in bacterial metabolic activity, indicating that CBO disrupts physiological processes and inhibits growth. In planta experiments showed that foliar application of CBO stimulated PAL activity in wheat leaves without visible phytotoxic symptoms. These findings demonstrate a multifunctional mode of action of CBO, combining direct antimicrobial effects with the elicitation of plant defence responses, and support its potential application in sustainable crop protection.