Enhancement of specialized metabolism, regeneration efficiency and biological activity in lavandin (Lavandula x intermedia cv 'Grosso')

This study aimed to improve essential oil composition by modifying terpene production in Lavandula x intermedia cv Grosso via mutagenesis to more closely resemble the oil of the commercially valuable essential oil from L. angustifolia or the medicinally active essential oil from L. latifolia. Additionally this study aimed to identify genes that control essential oil production in lavenders, and to determine the effect of essential oil composition on biological activity, specifically insecticidal and insect repellent properties. This study resulted in an improved method for the efficient regeneration of Grosso lavender, and applied this method to generate ten unique mutants. The transcriptomes of some mutants were sequenced, and thirty seven differentially expressed transcripts were identified as being involved in the biosynthesis and production of essential oil terpenes. The transcript expression results were confirmed by real-time quantitative polymerase chain reaction analysis. The lavender essential oil showing greatest biological activity against an invasive pest, spotted wing drosophila, was identified as Lavandula latifolia cv Medikus and the active constituents were identified through fumigation and spray toxicity assays as the monoterpenes 1,8-cineole and linalool. These oils showed strong fumigation and contact toxicity. In all, this thesis presents the generation, screening and analysis of unique L. x intermedia essential oil mutants, which represent both potential new commercial cultivars and model organisms for the investigation of the regulation and biosynthesis of essential oil terpenes.Arts and Sciences, Irving K. Barber School of (Okanagan)Biology, Department of (Okanagan)Graduat

Enhancing the regeneration efficiency of lavandin (Lavandula x intermedia cv Grosso) : effects of light quality, medium strength, phenolic control agents, and polyamines

An efficient protocol for the regeneration of lavandin (Lavandula x intermedia cv. 'Grosso') is reported. Thiadazuron (9 μM), a plant growth-modulating phenylurea, was used to induce callus formation and shoot initiation from cultured leaf explants. Newly emerged shoots were maintained on media containing 0.05 μM naphthaleneacetic acid to allow maturation, and then transferred to media containing 2.9 μM indole-3-acetic acid to allow root formation. The phenolic control agents polyvinylpyrrolidone (PVP), ascorbic acid, 2-aminoindane-2-phosphonic acid, and activated charcoal were tested for their ability to prevent shoot browning and death in culture. All agents except PVP were found to be effective, with ascorbic acid being most consistent in promoting development of healthy mature shoots. The effect of light type (red light vs. white light) and culture medium composition (full- and half-strength Murashige and Skoog or Llyod and McCown’s woody plant medium (WPM)) on rooting efficiency was also evaluated. Cultures on half-strength WPM in white light were found to have the highest rooting efficiency. Additionally, application of the polyamines putrescine, spermine, and spermidine were tested for their effect on rooting. While rooting efficiency was not improved with any of the treatments, spermine and spermidine were found to have an inhibitory effect at concentrations greater than 10 μM.Arts and Sciences, Irving K. Barber School of (Okanagan)Biology, Department of (Okanagan)ReviewedFacult

Insecticidal and oviposition deterrent effects of essential oils and their constituents against the invasive pest Drosophila suzukii (Matsumura) (Diptera: Drosophilidae)

Spotted wing drosophila (SWD), Drosophila suzukii (Matsumura), is an important new invasive pest of stone and berry fruits in North America and current control methods require frequent application of synthetic pesticides. This has created a need for new and environmentally friendly biopesticides for the control of SWD. This paper investigated the potential of nine essential oils from avocado (Persea americana Mill.), neem (Azadirachta indica A. Juss), kukui nut (Aleurites moluccana L.), macadamia nut (Macadamia integrifolia Maiden & Betche), spike lavender (Lavandula latifolia Vill.), Grosso lavandin leaf and flower (Lavandula × intermedia cv 'Grosso'), and Provence lavandin leaf and flower (Lavandula × intermedia cv 'Provence') as well as three major monoterpene constituents of lavender essential oils: 1,8-cineole, 3-carene and linalool for their ability to control SWD through fumigation and contact toxicity assays as well as oviposition deterrent activity. Linalool was found to be the most effective monoterpene in fumigation assays (EC50 1.85 µL/L air) and spike lavender floral essential oil was found to be the most effective whole oil (EC50 3.79 µL oil/L air). In contact toxicity assays 1,8-cineole (EC50 0.67%) was the most effective monoterpene while avocado (EC50 0.54%) and spike lavender (EC50 0.69%) oils were the most effective whole oils. No significant oviposition deterrent activity was observed. This report indicates that L. latifolia essential oil and commercially available avocado oil are strong lead candidates for management of SWD. Furthermore the activity of L. latifolia essential oil is likely due to the high content of 1,8-cineole and linalool. This is the first report of significant insecticidal activity by these oils and compounds against SWD.Arts and Sciences, Irving K. Barber School of (Okanagan)Biology, Department of (Okanagan)ReviewedFacult

The Morphoregulatory Role of Thidiazuron: Metabolomics-Guided Hypothesis Generation for Mechanisms of Activity

Thidiazuron (TDZ) is a diphenylurea synthetic herbicide and plant growth regulator used to defoliate cotton crops and to induce regeneration of recalcitrant species in plant tissue culture. In vitro cultures of African violet thin petiole sections are an ideal model system for studies of TDZ-induced morphogenesis. TDZ induces de novo shoot organogenesis at low concentrations and somatic embryogenesis at higher concentrations of exposure. We used an untargeted metabolomics approach to identify metabolites in control and TDZ-treated tissues. Statistical analysis including metabolite clustering, pattern and pathway tools, logical algorithms, synthetic biotransformations and hormonomics identified TDZ-induced changes in metabolism. A total of 18,602 putative metabolites with extracted masses and predicted formulae were identified with 1412 features that were found only in TDZ-treated tissues and 312 that increased in response to TDZ. The monomer of TDZ was not detected intact in the tissues but putative oligomers were found in the database and we hypothesize that these may form by a Diels–Alder reaction. Accumulation oligomers in the tissue may act as a reservoir, slowly releasing the active TDZ monomer over time. Cleavage of the amide bridge released TDZ-metabolites into the tissues including organic nitrogen and sulfur containing compounds. Metabolomics data analysis generated six novel hypotheses that can be summarized as an overall increase in uptake of sugars from the culture media, increase in primary metabolism, redirection of terpene metabolism and mediation of stress metabolism via indoleamine and phenylpropanoid metabolism. Further research into the specific mechanisms hypothesized is likely to unravel the mode of action of TDZ and to provide new insights into the control of plant morphogenesis.Science, Faculty ofNon UBCChemistry, Department ofReviewedFacult