Monoterpene production and regulation in lavenders (Lavandula angustifolia and Lavandula x intermedia)

Lavenders (Lavandula) are widely grown for their essential oils, which have extensive applications in cosmetics, hygiene products and alternative medicine. The therapeutic and olfactory properties of lavender essential oils are attributed to monoterpenes, a class of low molecular weight (C₁₀) isoprenoids. Oil composition in these plants is primarily determined by plant genotype, but can also be influenced by developmental and environmental factors. In order to define some of the mechanisms that control monoterpene abundance in lavenders, I measured the abundance of quality-defining monoterpenes in several L. angustifolia and L. x intermedia cultivars grown in the Okanagan. Data obtained confirmed that essential oil yield, as well as the abundance of camphor, borneol, linalool, and limonene was species-specific. L. angustifolia cultivars contained high amounts of linalool but yielded little oil, whereas L. x intermedia cultivars were rich in camphor and total oil. Monoterpene abundance changed during flower development, and differed between vegetative and reproductive tissues indicating differential regulation of the biosynthetic pathways, or specialized ecological functions. The abundance of linalool correlated with the transcription of the linalool synthase gene, suggesting that linalool production is in part regulated transcriptionally. However, the degree of correlation between linalool abundance and linalool synthase transcription differed between L. angustifolia and L. x intermedia, suggesting additional, and differing mechanisms that control linalool abundance in these species. In addition, monoterpene abundances were subject to loss during storage and suboptimal detection, two factors that must be considered in future analyses. Results obtained in this study provide insight into the regulation of monoterpene production in lavenders, and build the basis for future research aimed at improving essential oil production in these plants.Graduate Studies, College of (Okanagan)Graduat