Human Genome Project Aids Soybean Genome Mapping

What's the difference between a soybean and a person? Besides the obvious, soybean plants have three fewer pairs of chromosomes--and about 1.7 billion fewer pieces of DNA.

Still, plant geneticist Perry B. Cregan borrows biotech tools from the human genome project to map soybean genes. Cregan is with USDA's Agricultural Research Service in Beltsville, Md.

The United Soybean Board has awarded more than a million dollars in grants to support soybean gene mapping by Cregan and other scientists around the country. Finding soybean genes to enhance yields and pest resistance could eventually lead to raising U.S. yields by several hundred million bushels a year.

Recently, Cregan found map markers near the first two of the four genes he thinks give the plant resistance to cyst nematodes. These microscopic roundworms rob farmers to the tune of 220 million bushels a year. He and University of Minnesota colleagues are seeking markers for the other two resistance genes.

One of the biotech tools from the human genome project is called "simple sequence repeats." Cregan and Nebraska colleagues are using it to search for yield-boosting genes in a wild ancestor of soybeans.

With simple sequence repeats or SSRs, the scientists can draw maps that allow them to systematically search for useful genes in the genome one section at a time.

With SSRs, the scientists have developed more than 300 lines of soybeans in which one-eighth of the original genome has been replaced by wild DNA fragments. These lines are fertile breeding ground for finding yield-boosting genes.

Scientific contact: Perry B. Cregan, ARS Soybean and Alfalfa Research Laboratory, Beltsville, Md., phone (301) 504-6070, fax (301) 504-5728, pcregan@nal.usda.gov.