Metabolomic and agronomic clustering of bioactive essential oils from cultivated spanish aromatic plants

Abstract

Essential oils (EOS) are volatile natural components extracted from aromatic plants with many biological activities including these related to plant protection against pests and diseases and are being considered as an alternative to synthetic pesticides. In this work, aromatic plants from 19 species belonging to different genera have been adapted to cultivation in preliminary field trials located in Aragon, Spain. These fields, with 50 plants of each species, were supplemented with drip irrigation from June to August (4 L h¹, 5-6 h week') for 3 years. Plants were manually harvested at 75% of blooming to evaluate yearly biomass production to be distilled in a steam distillation pilot plant, and the essential oil yield (EO?) (%) calculated. The EOs distilled between 2017 and 2019 were analysed by GC-MS and tested against a stored product pest model (Tribolium confusum) in repellency, direct contact (with filter paper or crystallized cellulose as carriers) or contactless toxicity (fumigation). Thirteen of the EOs showed at least one type of bioactivity against the model insect. Some species share similar compounds that could explain their bioactivity. despite agronomic data showed significant differences. Considering chemical composition, bioactivity and agronomic performance, the EOs were grouped using Rstudio as clustering and dendrogram plotting tool, resulting in five groups. Groups 3 (thymol, carvacrol and p-cymene) and 4 (piperitenone and piperitenone oxide) hold the strongest bioactivity (lowest EC50 values for repellency and toxicity, respectively). Therefore, this composition-bioactivity based grouping method holds potential to predict additional bioactivities of essential oils based on their chemical compositions, rather than phylogenetic relationships. Additionally, the agronomic data gatherted for each species allows for the election of the best performing species for cultivation.