Work on Plant Lignin Modification Published in PNAS Journal

Scientists at the Noble Foundation in Ardmore, Okla., announce a discovery that could dramatically improve value and profitability of alfalfa, one of the most important agricultural crops in the United States. The discovery relates to modifying a plant's lignin production. Lignin is a structural material found in all plants. Having no nutritional qualities, the presence of excessive lignin in plant feedstock reduces animal digestibility and negatively affects animal productivity.

The U.S. Dairy Forage Research Center in Madison, Wis., estimates that a 10 percent increase in alfalfa fiber digestibility would lead to a $350 million increase in U.S. milk/beef production each year and a 2.8 million-ton annual decrease in manure solids. The reduction in natural lignin production in important forage crops, like alfalfa, will increase profitability for agricultural producers, enhance animal productivity and reduce the environmental impacts of large-scale animal operations.

In a paper published this week in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), Dr. Richard A. Dixon, director of the Noble Foundation's Plant Biology Division, and his collaborators detail their reduced-lignin transgenic alfalfa lines, which were produced by "knocking out" or down regulating certain genes that lead to lignin production.

"We targeted three genes that were believed to be involved in the production of lignin," Dixon said. "We found that the independent down regulation of two of these genes vastly improved digestibility [by significantly more than 10 percent]. We achieved both a large decrease in lignin content and an accompanying change in lignin composition. The digestibility improvement was far greater than we or other researchers have been able to achieve so far."

Dixon also pointed out that this work demonstrates, for the first time, that the key to improving digestibility in alfalfa is the reduction in lignin level rather than changes in lignin composition. Dixon is an expert in the field of enhancing forage digestibility through lignin modification, and his research also focuses on the use of plants to produce natural compounds to benefit human and animal health.

Alfalfa is the fourth most widely grown crop in the United States. This high-protein plant is the major feed source for dairy cows and also is an important feedstock for beef cattle and sheep, directly impacting milk, beef and wool production in the United States and abroad.

To view the full version of the paper "Targeted down-regulation of cytochrome P450 enzymes for forage quality improvement in alfalfa (Medicago sativa L.)," go to www.pnas.org/papbyrecent.shtml.

PNAS is one of the world’s most cited multidisciplinary scientific serials. Since its establishment in 1914, it continues to publish cutting-edge research reports, commentaries, reviews, perspectives, colloquium papers and actions of the Academy. Coverage in PNAS spans the biological, physical and social sciences.

###

The Samuel Roberts Noble Foundation, Inc. (www.noble.org), headquartered in Ardmore, Okla., is a nonprofit organization conducting agricultural, forage improvement and plant biology research; assisting farmers and ranchers through educational and consultative agricultural programs; and providing grants to nonprofit charitable, educational and health organizations.