Gene Offers Key to Cleaner Paper-Making, Better Feeds

By Jill Lee
January 14, 1997

Plants don’t have bones, so why do corn stalks and pine trees have such perfect postures? One reason: They have a substance called lignin that helps them transport water and stand up straight. Unfortunately, tough, stringy lignin also poses problems in paper production and feed quality.

Solutions may come from researchers with the U.S. Department of Agriculture. They found a gene that could change the structure of corn lignin so it disintegrates more easily. That could allow farmers to retain lignin’s benefits, such as pest resistance, while reducing its drawbacks, such as lower feed digestibility in silage.

Researchers suspect the corn gene has a counterpart in paper-making pine trees. Pine lignin that breaks down more easily could reduce the paper industry’s dependence on chemicals that can damage water quality.

“Paper comes from a tree’s cellulose, which has to be separated from its lignin. Mills do this with chemicals such as caustic soda, sulfur and chlorine, which are all pollutants,” said geneticist Paul Sisco with USDA’s Agricultural Research Service here. “It doesn’t matter if you work in a paper mill or live near one--everyone wants safe, effective alternatives to these solvents.”

“The paper industry spends millions on lignin removal and related clean-up costs, so even a small change in removability could generate dramatic savings,” said study collaborator Ross Whetten, assistant forestry professor at North Carolina State University.

A North Carolina State University study in 1988 noted that a 5 percent reduction in tree lignin content could result in annual savings of $100 million. Although this technology would not reduce overall lignin, even enhanced extractability has enough potential value to warrant research, Whetten said.

Sisco and ARS technician Wilfred Vermerris found a genetic mutation in a corn plant that changes the plant’s lignin.

“Not all lignin is alike. Lignin is actually made of three kinds of molecules, and other researchers found altering the ratio determines how easily the lignin degrades,” said Vermerris. “It just happens this gene allows you to make those kind of changes.”

Research on this gene and how it directs cells could also lead to ways to enhance lignin strength. This could appeal to farmers who don’t use silage and like the way strong lignin protects their crops from pests and storms. It might also be used by industries that sell lignin as a chemical additive.

Scientific contact: Paul Sisco, Plant Science Research Unit, Agricultural Research Service, USDA, Raleigh, N.C. 27695-7614. Telephone: (919) 515-3309; fax (919) 515-7959