Metabolic engineering of wine grapes with improved flavonoid-based health properties

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Anthocyanins are naturally occurring flavonoid compounds that impart red to purple colours to skins of dozens of different fruits such as apples, grapes, blueberries, and raspberries. Over 600 different anthocyanins have been identified in plants.  Numerous health benefits for humans have recently been attributed to specific anthocyanin extracts, including anti-cancer properties, treatment of diabetic retinopathy, and benefits towards reduced blood pressure, protection against LDL oxidation, and boosts to the immune system including reduced inflammation. The mechanisms underlying these health benefits are associated with antioxidant, anti-inflammatory, and anti-tumour properties. Previous studies have shown that fruits from different plant species preferentially accumulate particular types of anthocyanins, resulting in significantly different bioactive capacities as well as variable pigment intensities and hues.  For example, "cane" fruits such as raspberries accumulate anthocyanins derived from a dihydroquercitin precursor that have superior antioxidant properties to those synthesized in commercially important European wine grape varieties, which are predominantly dihydromyricetin-type. While previous work has been devoted to characterizing antioxidant activities of total anthocyanin extracts from cane fruits and grape berries, the molecular biology underlying the production of the apparently healthier proportions of anthocyanin compounds in cane fruit remains unknown.  My lab will: 1) determine the molecular basis for preferential production of dihydroquercitin-type flavonoids in a cane fruit species with reported highest natural antioxidant capacity, black raspberry, in comparison to the important wine grape cultivar, Pinot Noir, and 2) investigate means to metabolically engineer wine grape to increase the production of dihydroquercitin-type flavonoids relative to dihydromyricetin-type flavonoids.  My lab anticipates that this information will be useful in the long-term future for intragenic modification of existing commercial cultivars of grape and other red-berry species for increased health benefits to consumers.