The overall research focus of this project is to study regulation of biosynthesis of specific flavonoids (a major group of phenolic metabolites) to elucidate factors that control flavonoid synthesis, metabolism, and accumulation during plant development and growth. A major emphasis area is on regulation of enzymes called glucosyltransferases (GTs) that add glucose to different classes of flavonoids resulting in production of the compounds actually found in plant tissues. Well over 100 putative secondary product GTs can be predicted from sequence analysis of various plant genomes; only a relatively small number of these gene products have been functionally characterized and the majority of these belong to a group of GTs that add glucose to flavonols and/or anthocyanins at the 3-OH position. This research uses grapefruit as the model system as this plant has been shown to have GT enzymes that act on different flavonoids. Also, some candidate clones are already available for characterization. Specific goals of this research are to test the hypotheses that the grapefruit leaf putative GT clones are secondary product GTs, specifically flavonoid GTs, and that they have properties that may make them subject to regulation at the biochemical level. In addition, studies designed to test hypotheses related to GT structure/function by determining whether or not particular structural feature(s) of these proteins are responsible for their unique properties will be initiated.
Broader Impact: This research provides quality training and educational opportunities to undergraduate students and master's level graduate students at East Tennessee State University, a primarily undergraduate institution located in an economically disadvantaged region. It also provides an opportunity for a postdoctoral research associate to obtain experience and requisite skills for forming an active research program at an undergraduate institution and developing research activities in support of teaching and mentoring student research. The basic science and modern approach of this project will provide a good launching point for discussions during weekly lab meetings and journal clubs. In addition, the project personnel will be involved in outreach activities to strengthen K-12 science education.
