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