Scientists Discover New Enzyme, Process for Condensed Tannin Production

Potential Benefits to Agriculture, Human Health and the Environment

ARDMORE, Okla., Jan. 16 /PRNewswire/ -- Scientists in Oklahoma and Mississippi announced today a breakthrough in determining how plants produce condensed tannins, naturally occurring compounds that provide a variety of nutrition and health benefits to animals and humans. Published in the January 17 edition of Science, the researchers' discovery of a new enzyme (anthocyanidin reductase or ANR) allowed them to use biotechnology to produce condensed tannins for the first time in a plant tissue that doesn't naturally make these molecules.

Condensed tannins are perhaps best known as the potent antioxidants in grapes, cranberries and green tea. In humans, condensed tannins have been shown to have anti-cancer properties, as well as a positive impact on heart disease, immune systems and urinary tract infections. In ruminants, such as sheep and cattle, condensed tannins improve digestion and reduce the occurrence of animal "bloat" by decreasing methane gas production, which represents a viable solution to reducing greenhouse gas in the environment.

The pathway that leads to the synthesis of condensed tannins has been widely studied. However the critical step in the production of epicatechin, the building block of condensed tannins, has been missing. Researchers from The Samuel Roberts Noble Foundation, the University of Mississippi and Southeastern Oklahoma State University teamed together to find that the gene BANYULS encodes the newly discovered enzyme ANR, which converts the red pigments that usually accumulate in a plant's flowers into epicatechin. With this discovery, they were able to produce condensed tannins in tobacco leaves, which do not usually contain them. This lays the groundwork for making condensed tannins more readily available in the parts of plants which animals and humans eat.

"This is the first step in using biotechnology to increase condensed tannin availability in plant tissues, which will lead to improved forages for cattle and sheep as well as enhanced food products to benefit human health," said Dr. Richard Dixon, the study's lead scientist and director of the Noble Foundation's Plant Biology division. "It is yet another example of how plant biotechnology can benefit animals, humans and the environment."

The researchers will next work on developing improved varieties of alfalfa and other forage legumes rich in condensed tannins incorporating this technology. Dixon further plans to investigate the application of this discovery in crops such as cranberries, grapes and tea.

The Samuel Roberts Noble Foundation (, a non-profit organization headquartered in Ardmore, Oklahoma, operates to enhance agricultural resources management and plant productivity through consultation, demonstration, applied biotechnology and basic research and serves communities through charitable grants.

For a copy of the complete article published in Science, contact the AAAS Office of Public Programs at 202-326-6440 or [email protected].

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