Improved resistance against three diseases of U.S. soybeans has now been found in soybean plants from China, the crop’s ancestral home.

U.S. soybeans have been bred to enhance yields. But inbreeding can make genetic material progressively less diverse. Eventually, yields hit a plateau. New diseases--and new strains of old ones--make current varieties vulnerable. But in recent screening trials, scientists with USDA’s Agricultural Research Service found improved resistance to Sudden Death Syndrome, white mold and brown stem rot. Eventually, U.S. growers could get new, higher-yielding commercial varieties thanks to improved disease resistance and other important traits.

The new discoveries emerged from an unprecedented germplasm exchange with China that began in 1992 under a cooperative agreement with the Chinese government. The germplasm includes dozens of modern cultivars and more than 2,000 primitive strains. It greatly expands genetic sources from which researchers with ARS, universities and private companies can tap valuable traits for improving yields and disease resistance.

The Chinese lines have joined the U.S. Soybean Germplasm Collection maintained by ARS in Urbana, Ill. They constitute the collection's largest acquisition of Chinese germplasm in 60 years and come from a broader geographical area than previous additions. The exchange is supported by a consortium of ARS, Illinois and Iowa soybean growers’ associations, University of Illinois and Iowa State University.

Meanwhile, public- and private-sector researchers are cooperating to compare 60 modern Chinese varieties with contemporary U.S. varieties for productivity and genetic differences at the DNA level. This research will allow scientists to select high-yielding, genetically diverse parents from both countries, so U.S. farmers can achieve long-term yield gains. The collaborators include land-grant universities in Arkansas, Georgia, Maryland and Minnesota; ARS laboratories in Urbana, Ill.; Beltsville, Md.; and Raleigh, N.C.; Pioneer Hi-Bred International and Asgrow Seed Company.

Scientific contacts: Thomas E. Carter, Jr., ARS Soybean and Nitrogen Fixation Lab, Raleigh, N.C., phone (919) 515-2734, fax (919) 856-4598, tommy_carter@ncsu; Glen Hartman, ARS Crop Protection Unit, Urbana, Ill., phone (217) 244-3258, ghartman@uiuc.edu; Randall L. Nelson, ARS Plant Physiology and Genetics Research, Urbana, Ill., phone (217) 244-4346, fax (217) 333-4639, rlnelson@uiuc.edu.