Xie, DeYu , Zachary, Christopher , zhou, lili .
Characterization of Proanthocyanidin Biosynthesis in Engineered Plants.
Proanthocyanidins (also called condensed tannins) are polymeric and oligomeric flavan-3-ol units mainly linked by C 4-C8 carbon bonds. They are potent antioxidant reagents having multiple beneficial effects on human health, such as protective activities against cardiovascular and cancer diseases. In addition, they are used in forage fodder to prevent ruminant animals from bloat disease. As a result, metabolic engineering of PAs in food and forage crops is of agricultural significance for the purpose of developing value-added products. We here at the first time report the characteristics of engineered PAs synthesized by coupled PAP1 and ANR transgenic model plants (Xie et al. 2006, Plant journal, vol. 45, page 895-907). Different oligomeric molecular fractions of PAs were isolated from transgenic tobacco leaf tissues by using column chromatography separation and characterized by using a HPLC-MS based profiling. The main monomeric molecules included epicatechin and epiafzelechin. Ent-gallocatechin was also detected. The detected dimeric PAs candidates included epicatechin-epicatechin, epiafzelechin-epicatechin and epicatechin-epigallocatechin. Epicatechin-4 beta-8 epicatechin (Procyanidin B2) was definitively identified as one of the main dimeric PA molecules made by transgenic plants. One candidate of identified trimeric PA molecules was predicted to be epicatechin-epicatechin-epicatechin. Our results indicated that the monomeric molecule of epicatechin derived from the engineered PA pathway in transgenic plants, serving as the starter unit and possibly main extension units, forms the foundation of PA polymerization in engineered plants. The biosynthesis and possible mechanism of PA formation in the engineered plants will be discussed in this presentation.
Log in to add this item to your schedule
Plant Metabolomics and Phytochemistry
1 - North Carolina State University, Plant Biology, 4219 Gardner Hall, Raleigh, NC, 27695, USA
2 - North Carolina State University, Biology
3 - North Carolina State University, Plant Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM