A group of U.S. Department of Agriculture-Agricultural Research Service researchers in Iowa State University's agronomy department are sequencing the soybean genome to discover the similarities and differences with its relatives in the legume family.

Working in collaboration with the Department of Energy's Joint Genome Institute, Randy Shoemaker, Steven Cannon and their colleagues hope comparisons of the DNA in related plants can help researchers understand how agronomic traits evolved and, in turn, aid plant breeders in creating improved crop varieties.

"This information will be especially useful in helping plant breeders target oil and protein quality, disease resistance and other valuable traits," Cannon said. "This information can speed up the entire breeding process. For example, breeders could evaluate seedlings rather than waiting for the trait to be visible in mature plants."

Studies of the all the DNA in a plant, known as the genome, are underway in several species, including another ISU project focusing on the corn genome.

This year the Joint Genome Institute announced soybean genome sequencing. As part of this effort, Cannon and the USDA-ARS research group at Iowa State will work with others at many institutions to assemble and make sense of this sequence.

Including soybean, there are three species in the legume family with genome sequencing projects. Research programs to sequence the legumes Medicago truncatula (closely related to alfalfa) and Lotus japonicus have been underway for some time at other institutions.

Cannon and colleagues working on these two sequencing projects recently published a paper comparing the genomes in the journal Proceedings of the National Academy of Science. One of the main conclusions, according to Cannon, is that the species have much in common.

"Although these species have been separated for about 40 million years, very long stretches of the chromosomes directly correspond with one another," Cannon said. "This will help researchers transfer knowledge about important traits between these and other legume species."

Of special interest to the team is uncovering how soybeans express traits that are beneficial to human health and how the plants fix nitrogen, which is used for producing protein and other bio-molecules.

"This information will be very helpful in better understanding biochemical pathways that produce health-promoting compounds such as isoflavonoids and other beneficial compounds," Cannon said.

The genome sequence also will help determine what genes are helpful in creating resistance to common diseases such as Phytophthora (stem rot) and Asian soybean rust.