ISU to play vital role in solving corn genome

Corn Genome

If genomes were jigsaw puzzles, the corn genome would have twice the pieces as the human puzzle.

Scientists in Iowa State's Center for Plant Genomics have been chosen to participate in a $29.5 million, three-year project to sequence the entire corn genome -- to decode the entire genetic blueprint for the plant researchers call maize.

Patrick Schnable, director of the Center for Plant Genomics, said it's the most ambitious genome sequencing project yet -- even more complicated than the human genome. Although both are about the same size, corn has an estimated 50,000 to 60,000 genes. Humans have about 26,000 genes. Decoding the maize genome will let researchers discover the role each gene plays in corn's development and function. "That will allow more precise changes to make maize more useful," said Schnable, professor of agronomy and genetics, development and cell biology.

"It's a wonderful source of food and livestock feed," he added. "But we see a much greater future as a source of fuel and industrial substrates." Having the entire genetic code will help scientists genetically modify corn so it converts to ethanol more efficiently. Corn also could be more easily modified to produce pharmaceuticals or industrial materials.

Sequencing the genome also would make it easier to modify maize so it uses nitrogen more efficiently and resists drought, Schnable said. "Water is becoming a very important commodity for world peace," he said. "If we can develop crops -- and we will be able to -- that can tolerate drought and lack of nitrogen, they will help to promote world stability."

For the project, researchers will focus on B73, a corn cultivar developed at Iowa State that is the basis for many of the world's commercial lines of corn. It's used widely in corn genetics research.

To sequence the genome, scientists first break corn's DNA into segments. The segments are analyzed to determine the precise arrangement of four chemical bases -- C, G, T and A -- that make up the genome. Then the billions of base pairs are reassembled into a complete genome.

Iowa State scientists will play a major role in the last step: assembling the DNA sequence data. The job plays on two of Iowa State's strengths: gene mapping, in which the locations of genes are plotted on corn chromosomes, the cellular structures in which DNA is bundled. Mapping provides "landmarks" as the genome is assembled.

The Genome Sequencing Center at Washington University School of Medicine in St. Louis will generate the sequence data. The University of Arizona at Tucson and Cold Spring Harbor Laboratory in New York also are participating. The National Science Foundation and the federal departments of agriculture and energy are financing the project.

Schnable and Srinivas Aluru, professor of computer and electrical engineering, head Iowa State's team. The science foundation awarded Iowa State a separate $600,000 grant, with an additional $300,000 match from the Office of Vice Provost for Research and Plant Sciences Institute, for a high-performance computer. The machine, expected to be among the most powerful in the world, will be used for corn genome sequencing and other projects. Srinivas Aluru, professor and associate chair-research of electrical and computer engineering, will lead the grant.