ESSENTIAL OILS AS ALLELOPATHIC AGENTS: BIOCONVERSION OF MONOTERPENES BY GERMINATING WHEAT SEEDS

Abstract

Abstract Monoterpenes present in essential oils are very powerful germination inhibitors. In this study we describe the fate of a number of components of essential oils, after they are applied to wheat seeds to inhibit seed germination. Wheat seeds exposed to exogenous application of essential oils are able to metabolize their monoterpene components. A high correlation between the level of inhibition of seed germination and the amount of total metabolites in the seed was observed. This suggests that the catabolism of monoterpenes is part of an existing detoxification process. Most of the monoterpenes were either reduced or oxygenated. The products and possible metabolic pathways of various monoterpenes such as carvone, α-thujone, artemisia ketone, α-terpineol, γ-terpinene, p-cymene and δ-3-carene are discussed. Our findings demonstrate the potential of essential oils as allelopathic agents and provide an insight into their mode of action. This information can also be used to develop new methods for converting essential oils to new natural chemicals.