Project Summary: Tannin Biosynthesis in Medicago Species

Condensed tannin biosynthesis and manipulation

Project Objectives:
We are using genomic, genetic and biochemical approaches to elucidate the pathways of condensed tannin biosynthesis and polymerization in plants, using Medicago truncatula and Arabidopsis thaliana as model systems. Specific target include anthocyanidin reductase (ANR), a new enzyme we recently discovered, and various transcriptional regulators. We are working to introduce condensed tannins into forage legumes, including alfalfa and white clover, which do not naturally make these compounds in the leaves, in order to produce varieties that do not cause pasture bloat. We are also engineering (-)-epicatechin (the product of ANR) into plants as a health promoting nutraceutical.

Present Lab Personnel on Project:

Past Personnel:

Dr Shashi B. Sharma
Dr De-Yu Xie

Collaborators:

Dr Daneel Ferreira, University of Mississippi, Oxford, MS
Dr Steven Temple, Forage Genetics International, West Salem, WI
Dr Zeng-Yu Wang, Noble Foundation

Funding:

Noble Foundation
Forage Genetics International

Recent Publications:

Pang, Y., Peel, G.J., Sharma, S.B., Tang, Y. and Dixon, R.A. (2008). UGT72L1 is an epicatechin-specific glucosyltransferase associated with proanthocyanidin biosynthesis in the model legume Medicago truncatula. Proceedings of the National Academy of Sciences, USA, in review.
Pang, Y., Peel, G.J., Wright, E., Wang, Z-Y, and Dixon, R.A. (2007). Early steps in proanthocyanidin biosynthesis in the model legume Medicago truncatula. Plant Physiology 145, 601-615.
Peel, G.J. and Dixon, R.A. (2007) Detection and quantification of engineered proanthocyanidins in transgenic plants. Natural Product Communications 2, 1009-1014.
Tian, L., Pang, Y. and Dixon, R.A. (2007). Biosynthesis and genetic engineering of proanthocyanidins and (iso)flavonoids. Phytochemistry Reviews, in press.
Marais, J.P.J., Deavours, B.E.,Dixon, R.A. and Ferreira, D. (2006). The stereochemistry of flavonoids. In The Science of Flavonoids, ed E. Grotewold, Springer, pp1-46.
Xie, D.-Y., Sharma, S.B., Wright, E., Wang, Z.-Y. and Dixon, R.A. (2006). Engineering plants for introduction of health-beneficial proanthocyanidins. Plant Journal 45, 895-907.
Sharma, S.B. and Dixon, R.A. (2005). Metabolic engineering of proanthocyanidins by ectopic expression of transcription factors in Arabidopsis thaliana. Plant Journal 44, 62-75.
Xie, D.-Y. and Dixon, R.A (2005). Proanthocyanidin biosynthesis- still more questions than answers? Phytochemistry 66, 2126-2143.
Dixon, R.A., Xie, D.-Y., and Sharma, S.B. (2005). Tansley Review. Proanthocyanidins- a final frontier in flavonoid research. New Phytologist, 165, 9-28.
Xie, D.-Y., Sharma, S.B. and Dixon, R.A. (2004). Anthocyanidin reductases from Medicago truncatula and Arabidopsis thaliana. Archives of Biochemistry and Biophysics 422, 91-102.
Xie, D.-Y., Sharma, S.B., Paiva, N.L., Ferreira, D. and Dixon, R.A. (2003). Role of anthocyanidin reductase, encoded by BANYULS, in plant flavonoid biosynthesis. Science 299, 396-399.
Dixon, R.A. (2004). Molecular improvement of forages- from genomics to GMOs. In Molecular Breeding of Forage and Turf, eds Z-Y Wang and A. Hopkins, Kluwer Academic Publishers, 1-19.
Dixon, R.A. and Sumner, L.W. (2003) Legume natural products. Understanding and manipulating complex pathways for human and animal health. Plant Physiology 131, 878-885