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Wild Australian Soybean Relatives Hold Genes for Nematode Resistance

By Linda McGraw
July 17, 2001

Future soybeans may have stronger resistance to a pest that has long plagued Midwestern farmers, thanks to the diligence of Agricultural Research Service (ARS) and University of Illinois scientists in Urbana, Ill.

The pest, the soybean cyst nematode (SCN), was first found in North Carolina in 1954. It has consistently overcome the best genetic resistance available in soybeans, and its presence in most soybean-producing states can mean a 5 to 10 percent yield loss annually. In Illinois alone--where 10 million acres of soybeans are grown--this could mean millions of dollars in losses.

ARS plant pathologists Glen L. Hartman and Gregory R. Noel and University of Illinois scientist Ted Hymowitz screened 328 accessions of Glycine tomentella, the wild Australian relative of soybeans. They found 50 percent of these germplasm accessions had high levels of resistance to Race 3 nematodes, the most common type in the Midwest. There are nine known SCN races in the United States.

In the greenhouse, the researchers inoculated the wild G. tomentella with nematode eggs and cysts containing eggs. The outcome: no reproduction of the nematodes on resistant plants. Hymowitz has crossed G. tomentella and commercial soybeans without using biotechnology methods. ARS scientists are testing the populations of these crosses to determine if the resistance genes have been transferred. This work represents just a portion of the untapped resources in wild perennial relatives of soybeans that possess resistance to many other soybean pathogens, according to Hartman.

Hartman and Noel are based at ARS's Soybean/Maize Germplasm, Pathology and Genetics Research Unit in Urbana.

The germplasm is part of the USDA Soybean Germplasm Collection. This work is being funded by ARS, the University of Illinois, the Illinois Council for Food and Agricultural Research (C-FAR) and the Illinois Soybean Promotion Operating Board (ISPOB).

ARS is the chief scientific research agency in the U.S. Department of Agriculture.