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UBC Theses and Dissertations

The novel use of metabolomics as a hypothesis generating technique for analysis of medicinal plants : Ligusticum canbyi Coult. & Rose and Artemisia tridentata Nutt. Turi, Christina


In response to the environment, plants produce a phytochemical arsenal to communicate and to withstand abiotic and biotic pressures. The average plant tissue contains upwards of 30,000 phytochemicals. The vast majority of approaches used to study plant chemistry are reductionist and only target specific classes of compounds which can be easily isolated or detected. Metabolomics is the qualitative and quantitative analysis of all metabolites present in a biological sample. By providing researchers with a phytochemical snapshot of all existing metabolites present in a sample, metabolomics has allowed researchers to study plant primary and secondary metabolism in ways that were never done before. The first objective of this thesis is to identify candidate species for studying plant neurochemicals. Statistical analysis using residual, bayesian and binomial analysis was applied to the University of Michigan’s Native American Ethnobotany Database and revealed that the genera Artemisa and Ligusticum are used most frequently during ceremony and ritual. Plant melatonin, serotonin, γ-aminobutyric acid, and acetylcholine were quantified in Artemisia tridentata Nutt. and Ligusticum canbyi Coult. & Rose. Significant variability was observed between tissue types, germplasm line and species. Manipulation of cholinergic signalling in A. tridentata led to changes in auxin, melatonin and serotonin levels, and suggests cross-talk between cholinergic and indoleamine pathways could be occurring in plants. The second objective of this thesis is to develop novel statistical and biochemical tools for analyzing metabolomic datasets and hypothesis generation. Datasets were generated using ultra performance reverse phase chromatography with time of flight mass spectrometry detection. Between 16,000 and 40, 000 metabolites were detected in L. canbyi and A. tridentata root and leaf tissues respectively. Principal component analysis, synthetic biotransformation, significant ion generation, putative identification and logical algorithms were applied in order to develop hypotheses and research approaches for pthalide biosynthesis, plant responses to stress, and the biological activity of smoke. Metabolomics, as a field of study, is still in its infancy. Thus approaches to effectively mine datasets are still needed, and provide researchers with new ways to examine the processes which regulate the production of primary and secondary metabolites in vivo.

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