Discrimination and prediction of the chemical composition and the phytotoxic activity of Wedelia trilobata essential oil (EO) using metabolomics and chemometrics

Understanding metabolic variations of plant essential oils (EOs) in response to different growth conditions is of great importance for bioprospecting and standardizing purposes. In this study, combined gas chromatography-mass spectrometry (GC-MS) based metabolomics and bioassay experiments were carried out to identify chemical differences in W. trilobata EO grown in field and those grown in controlled conditions. Subsequently, the chemical profiles were correlated with their ability to inhibit germination, shoot and root growths of weedy rice and lettuce. Results showed that EO grown in controlled condition was abundant in sesquiterpene hydrocarbons whereas field-grown EO accumulated large amounts of monoterpenes. Principal component analysis (PCA) and orthogonal partial least square discriminant analysis (OPLS-DA) indicated the chemical composition of isolated EOs varied considerably. PLS regression revealed that seed germinations of weedy rice and lettuce were susceptible to W. trilobata EO grown in controlled condition and nonanal may contributed to the phytotoxic activity of the EO. The field-grown EO exhibited strong inhibitory activity against shoot and root growths of weedy rice and lettuce, while alpha-phellandrene, terpinen-4-ol, trans-pinocarveol and pinocarvone might be responsible for the inhibitory activity. The findings highlight the combination of metabolomics and bioassays to provide a metabolic understanding and bioprospecting potential of W. trilobata EO as bio-herbicides.

Automated summary

This study used metabolomics and bioassay experiments to understand the chemical differences and inhibitory effects of W. trilobata essential oil (EO) grown in different conditions. It was found that EO grown in the field contained large amounts of monoterpenes, while EO grown in controlled conditions was rich in sesquiterpene hydrocarbons. The field-grown EO showed strong inhibitory effects on the growth of weedy rice and lettuce, while certain compounds like alpha-phellandrene, terpinen-4-ol, trans-pinocarveol, and pinocarvone were found to be responsible for the inhibitory activity.