West Lafayette, Indiana
November 1, 2002

Everyday products from food to chairs could be improved through research led by a Purdue University scientist and funded by a new four-year, nearly $6 million National Science Foundation grant.

Nick Carpita, Purdue plant biologist, will head the investigation of the formation, development and growth of plant cell walls. The research team will include scientists from Purdue, the University of Florida, University of Connecticut, University of Wisconsin and the National Renewable Energy Laboratory, a Department of Energy contract facility based in Golden, Colorado.

"This project is to determine the function of all the genes involved in plant cell walls," said Carpita, professor of botany and plant pathology. "If we learn the way cells stick to each other, we may be able to control the softening of fruits and vegetables and increase the shelf life."

They also may be able to increase food-derived health benefits, such as those found in oat and barley products, which have the ability to lower serum cholesterol and reduce diabetic insulin demand. These grains contain certain plant polysaccharides - groups of nine or more simple sugars linked together - such as beta glucan. But only one group of plants has beta glucans, Carpita said.

"If we learn how these polysaccharides are synthesized, or if we can prevent their degradation during seed formation, we might be able to improve glucan content in rice, wheat and corn, grains that are particularly low in that particular polymer," he said.

Cell walls are composed of polymers, or chains of molecules, that assemble into very complex structures. Many products people use daily are made of plant cell wall material.

"You're writing on one (paper); you're sitting on another (wooden chair)," Carpita said. "You probably enclosed your house using a lot of wood products, which are pretty much plant cell wall."

Knowledge of plant cell wall development and structure could lead to altering some of the polymers, such as lignin and carbohydrates, to make fodder more digestible for livestock, improve paper quality and improve corn stover for use as a biofuel, he said.

The researchers are focusing on the commonly used research model plant Arabidopsis and on maize (corn), because the two plants have distinct types of cell walls with different compositions, architectures and ultimately, end uses.

"Because of these differences in wall composition, we expect that several genes involved in cell wall generation and development will be unique," Carpita said. "We're taking advantage of the well-known genetics of each of these models to take us from mutation to the gene."

The scientists will use infrared spectroscopy, similar to equipment used for satellite imaging of the Earth, to identify and characterize mutant genes that affect plant cell wall architecture.

Another research team member, Maureen McCann of the John Innes Center in Great Britain, hatched the idea of using infrared spectroscopy to screen for mutants.

"Often it's difficult to know whether a mutation has any consequences for a plant if no change is visible in its growth habit, or specifically whether the cell wall has been altered," McCann said. "We need a technique that detects invisible changes and that is sensitive to molecular bonds present in cell walls.

"An infrared spectrum takes less than a minute to collect this information from a sample. This means we can test hundreds of samples a day."

The infrared spectroscopy solves one of the researchers' problems, but it can't explain how the wall chemistry was altered in these mutations, Carpita said. So the investigators will use a variety of other methods to determine how simple sugars form, how they join to become polymers and how these polymers assemble into the biologically dynamic matrix that is a cell wall.

"We want to see the assembly of the sugars into polymers and then the joining of polymers into a framework and the stretching and discrete changes the framework, or cell wall, undergoes as cells enlarge," Carpita said. "Some plant cells have a propensity to enlarge as much as 10,000 times their
original size during plant growth."

The project has established a Web site to share information with other plant and biotechnology researchers. The team also is using the project as a basis for launching new teaching, outreach and intern programs, including attracting and assisting minorities in scientific and agricultural pursuits.

This funding is one of 23 grants totaling $75.6 million made this year under the NSF Plant Genome Research Program.

The other researchers participating in this collaborative grant project in addition to Carpita and McCann are:

• Purdue scientists Chris Staiger, Department of Biological Sciences; Bradley Reuhs, Department of Food Science's Whistler Center for Carbohydrate Research; Wilfred Vermerris, departments of Agronomy and Biological Engineering;
• Anthony Bleecker and Sara Patterson of the University of Wisconsin;
• Karen Koch and Donald McCarty of the University of Florida;
• Wolf-Dieter Reiter of the University of Connecticut; and
• Steven Thomas, National Renewable Energy Laboratory. Thomas will be working at the Purdue campus during this project.