Dissertation
BIOSYNTHESIS OF PLANT SPECIALIZED DITERPENOIDS: LEVERAGING METABOLIC AND TRANSCRIPTOMIC PROFILING FOR GENE DISCOVERY
Doctor of Philosophy (PhD), Washington State University
01/2017
Handle:
https://hdl.handle.net/2376/107536
Abstract
Plants produce a large number of natural products that serve both physiological and ecological roles for the plants but are also valued as medicines, fragrances, flavors, and in many other applications. One of the largest groups of natural products consist of specialized diterpenoids, some of which are known for their prominent therapeutic properties, and there are thus increased demands for clinical trials and the pharmaceutical market. The search for sustainable production methods of structurally complex diterpenoids, for example using biotechnological approaches, requires an in-depth understanding of diterpenoid biosynthesis. This study is aimed at elucidating the biosynthesis of abietane diterpenoids in Tripterygium regelii (project 1) and of paclitaxel in Taxus x media (project 2).
Despite the promising properties, there are only handful of study on abietane diterpenoids biosynthesis in Tripterygium at present. A robust approach is required to effectively discover the key genes relevant to the biosynthesis pathways. We took three steps to achieve that. First, we established and maintained the diterpenoid-accumulating- plant tissue cultures from which metabolites and transcriptome datasets were mined. Second, we identified the differentially metabolic and transcriptomic profiles between the producing- and non- producing tissues, hence narrowed down the selection of gene candidates. Third, we functionally characterized the selected gene candidates. Based on the identified genes and metabolites, we suggested a more detailed biosynthesis pathway for abietane diterpenoids in Tripterygium, and one putatively additional early step in paclitaxel biosynthesis pathway in Taxus.
Outputs of this study include: First, a proof of concept regarding the effectivity of transcriptome-metabolic integrated profiles in gene discovery. Second, identification of eight diterpene synthase genes in Tripterygium regelii, five of which may be directly involved in specialized diterpenoid biosynthesis, and one putative cytochrome P450 hydroxylase gene in Taxus media. Third, our results provide supporting evidence that diterpene synthases play key roles in generating great diversity of plant specialized diterpenoids. Fourth, we suggested an improved pathway of triptolide biosynthesis based on adventitious root culture metabolite profiles. Fifth, establishment of specialized diterpenoid- secreting- adventitious root culture of Tripterygium regelii, which can be scaled up for triptolide production.
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Details
- Title
- BIOSYNTHESIS OF PLANT SPECIALIZED DITERPENOIDS: LEVERAGING METABOLIC AND TRANSCRIPTOMIC PROFILING FOR GENE DISCOVERY
- Creators
- Fainmarinat Selviani Inabuy
- Contributors
- Bernd M Lange (Advisor)Helmut Kirchhoff (Committee Member)David R Gang (Committee Member)Sanja Roje (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Program in Molecular Plant Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 123
- Identifiers
- 99900581716501842
- Language
- English
- Resource Type
- Dissertation