Biodiversity and medicinal metabolites of rare and endangered Vietnamese plants using molecular genetics and proteomics

University of Technology Sydney. Faculty of Science.This thesis reports on an investigation into the molecular biology and metabolism of two species: , a critically endangered cycad; and , a traditional medicinal plant. The genetic diversity of both species was investigated to understand distributions, important for conservation and prioritisation of efforts in both species. Investigations on phytochemical accumulation and biosynthesis of metabolites and enzymes associated with the two types of phenotypes of . (broad leaf-BL and narrow leaf-NL) was undertaken to identify the medicinally superior sources of material for possible commercial utilisation. The genetic diversity of . and . was determined using Randomly Amplified Polymorphic DNA (RAPD) and Randomly Amplified Microsatellite Polymorphism (RAMP) techniques. The latter molecular method proved more useful in distinguishing between individuals and populations. Recommendations on future conservation and management for the two species are identified. The project then concentrated on . . The concentration of important anti-oxidative metabolites was investigated and compared between NL and BL phenotypes using spectrophotometric methods. BL had a significantly higher concentration of α-tocopherol, flavonoid, phospholipid and possibly glutathione (based on an air-dry weight (ADW) and protein basis). Stress biomarkers such as proline and malondialdehyde (MDA) were elevated in NL, indicating their roles in response to stress. Total protein increase in BL correlated with a reduction of proteases, particularly acid protease. In contrast, the enzyme and metabolite increase in NL may be associated with tissue degradation and an indication of stress in the natural forest area. Differentially expressed proteins were analysed between NL and BL to understand the mechanisms which facilitate the growth and development of BL, particularly the accumulation of some potentially valuable phytochemicals. By using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) coupled with mass spectrometer (MS), a range of upregulated proteins was identified. Some proteins were indicative of growth promotion and development in BL plants via diverse biological processes and molecular mechanisms, such as flavonoid biosynthesis, stress response, disease resistance and nucleic acid metabolism. The proteins identified supported plant growth and development processes and are of pharmaceutical importance, with possible therapeutic applications in mammalian disease treatment, particularly in cancer therapy. To conclude, . urgently requires a genetic rescue plan to protect it from extinction. Genetic conservation for . is also necessary to promote breeding, cultivation and system development for possible medicines. BL of . , which contains more diverse and superior concentrations of important phytochemicals and pharmaceutically related proteins should be positioned as an important commercial source for natural drug development