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Title: A metabolomics and transcriptomics comparison of Narcissus pseudonarcissus cv. Carlton field and in vitro tissues in relation to alkaloid production
Author: Ferdausi, A.
ISNI:       0000 0004 6422 7394
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2017
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The Amaryllidaceae alkaloids e.g. galanthamine (Gal), lycorine, narciclasine and pretazettine are noted for their pharmaceutical properties. The biosynthesis of alkaloids by plants using in vitro systems has been considered as a tool for drug discovery and production since total chemical synthesis is not economic. The biosynthetic pathways, especially for Gal, are starting to be understood, but still far from complete. This study focused on understanding biosynthesis in whole plants and developing cell culture systems that could be optimised for alkaloid production. Metabolite profiling and knowledge about probable genes involved in secondary metabolism and their regulation in different tissues will provide insight into the Narcissus plant biology related to alkaloid production. In vitro cultures of N. pseudonarcissus cv. Carlton were initiated from twin-scale explants, cultured on Murashige and Skoog agar medium (MS) fortified with different concentrations of growth regulators. Callus was obtained mainly from MS medium containing high concentration of auxin, while media with low auxin and MS basal medium gave bulblets with both white and green shoots. Regenerated bulblets developed from callus developed in both high and low auxin MS media. These tissue culture derived materials and field-grown samples were analysed using GC-MS for Gal content. The highest amount of Gal was obtained from basal plate tissue followed by bulb, leaves, and in vitro tissues. A trace amount of Gal was found in callus along with possibly other alkaloids. An NMR-based metabolomic analysis showed that the relative concentrations of compounds involved in phenylalanine and tyrosine metabolism, the initial stage biosynthetic pathways that yield the Amaryllidaceae alkaloids, were higher in field samples than in vitro samples. These results support the GC-MS findings of high Gal production in field samples. Initial RT-PCR analysis using gene specific transcripts possibly involved in Gal biosynthesis i.e. P450s. PAL, TYDC and OMT showed their expression in in vitro as well in field tissues, which is intriguing. A transcriptome analysis was performed comparing expression in the highest (basal plate) versus lowest (callus) Gal containing tissues. The transcriptome analysis results were in accordance with the previous findings, as it was observed that the transcripts involved in the initial biosynthetic pathways leading to precursors (tyrosine, phenylalanine) were up regulated in callus while the transcripts involved in later pathways leading to alkaloids were up regulated in basal plate.
Supervisor: Jones, Meriel ; Hall, Anthony Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral