By ANN HINCH
Assistant Editor

KANSAS CITY, Mo. — More than 200 years ago, President Thomas Jefferson authorized Meriwether Lewis and William Clark to travel west of the Mississippi River and explore the Louisiana Purchase, starting in what would eventually become Missouri.

Speaking at the National Corn Growers Assoc. Corn Utilization & Technology Conference in that state earlier this month, Dr. Patrick Schnable likened the corn genome mapping project to such exploration. Just as Congress funded Lewis’ and Clark’s work, he said it voted in 1998 to allocate funds for a corn genome program.
Sequencing the genome is a $30 million, three-year project, according to Schnable, director of the Center for Plant Genomics at Iowa State Univer-sity. “It’s at least as large as the human genome,” he said of the starchy yellow ear, which has approximately 50,000 genes. “Maybe more traits.”

By the end of 2008, he said the final version of genome sequencing should be available; a draft was presented at a national conference in February. The point is to determine the specific function of as many genes as possible, so crop engineers can tailor different corn for different purposes.

“We can’t immediately decipher how all that works … to grow a corn plant,” Schnable said, describing the slow process used to map each gene.

One example of possible reengineering has to do with corn stover. On one hand, it may be burned for fuel; however, leaving it in the field to break down in a no-till situation is beneficial for the soil, Schnable said.

“We need the fuel,” he pointed out, “but we can’t afford to degrade our agricultural soils to get it.”

If scientists know which genes control cell walls in different parts of the plant, they might be able to design a corn stalk so that the top part breaks down faster for stover fuel, and the bottom degrades slowly to help capture carbon dioxide into the soil.

It’s a type of carbon “sequestering” that could both reenergize Midwestern soils and work in farmers’ favor for carbon credits in the future. Schnable explained not only would crops get more nutrients, growers could benefit from selling those credits.

“This is not an insignificant contribution to farm income,” he said.
Sherry Flint-Garcia, a USDA research geneticist with the University of Missouri-Columbia, co-presented at the June 3 conference. Part of her work is studying how modern corn descended from teosintes, a Mexican grass, over the past 6,000-9,000 years.

She explained modern maize retains about 66 percent of the diverse traits that are in teosintes, despite cultivation that has weeded out undesirable characteristics and isolated those growers sought – more kernels and more ears, to name two.

While corn provides much more food than the few kernels that grow on an “ear” of teosintes, Flint-Garcia said those few kernels are higher in protein and lower in carbohydrates than corn. And, while farmers and scientists have bred out many undesirable traits, they’ve also narrowed the selection of traits modern corn geneticists have to manipulate – which means the ideal gene for producing a more biofuel-efficient plant, for example, might still be in teosintes.

For her part, Dr. Martha James studies the biochemistry of starches, which are used heavily in both livestock feed and human diets – and which are the chief attraction for the ethanol industry. An adjunct associate professor at Iowa State University, she is interested in understanding the physical structure of the cornstarch molecule.

To that end, she is studying how starch may be adjusted in corn for specific purposes. Corn to be grown for ethanol, for example, would be more useful if it had a more rapid conversion rate to glucose; but for human food, a slower conversion may be better to prevent quick absorption by the body, and could cut down on obesity and diabetes.

“We can engineer the corn to do anything we like,” Schnable said of the end goal of their work.

He added that researchers are interested in knowing what specifically growers and industries want from the corn plant, from a commercial perspective. If they know that, they’ll know which genes to concentrate on studying and manipulating.

To learn more, contact Schnable by e-mail at schnable@iastate.edu or by calling the Center for Plant Genomics at 515-294-0975.