Owens, Daniel

• Ph.D., Virginia Tech

• B.S., East Tennessee State University

Increasingly yields of health-promoting flavonoids is a significant challenge for nutraceutical  and medicinal applications. Flavonoids have antioxidant, anti-inflammation and anti-allergenic properties that provide pharmaceutical activity against infection and disease (e.g. heart disease and certain cancers) when consumed in the diet. The biochemical pathways that lead to the biosynthesis of the flavonoid core structure have been extensively studied in the model plant Arabidopsis demonstrating that metabolic organization and metabolon formation have a significant impact on the amounts and types of flavonoids that accumulate.  C. sinesis (orange) is a particularly suitable model system in which to base flavonoid metabolon studies as it is used to produce popularly consumed food products, uniquely accumulates medicinal early flavonoids and the genome sequence for the species that are now available. Furthermore, the blood oranges, unique orange cultivars that accumulate anthocyanins (late flavonoids), provide a rare opportunity to examine how the additional enzymes required to produce anthocyanins have differential regulation and impacts on flavonoid metabolon organization in the same species and how this might be manipulated to improve accumulation of medicinal flavonoids of interest. What remains unknown is how flavonoid enzymes are organized to form a metabolon in species that accumulate early flavonoids and the role played by derivatizing enzymes such as glycosyl-transferases (GTs). The central hypothesis is that accumulation of orange flavonoid end products depends upon formation of a metabolon. This hypothesis was formed by previous analysis of the Arabidopsis flavonoid metabolon, studies of flavonoid glycosylation and preliminary yeast-2-hybrid interaction data. There is a critical need to determine the enzymology and metabolic organization of a flavonoid metabolon in a nutritionally significant plant species with these characteristics to identify targets for improving content and quality of flavonoids for medicinal use.