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Sudden death syndrome causes an estimated $6 million to $40 million in soybean losses every year, depending on weather conditions. Development of resistant varieties is the best solution.–OVAL MYERS |
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| Resistance is best defense against soybean disease |
Researchers are close to a genetic solution to one of the most serious soybean disease problems in Illinois.
 "We've clearly found a major gene that is closely linked to sudden death syndrome and soybean cyst nematode. Further research is necessary, but we expect to be able to transfer resistance to both diseases in the near future," said Oval Myers, a plant breeder and geneticist at Southern Illinois University-Carbondale.
Sudden death syndrome (SDS) first appeared in Illinois soybean fields in 1985. It causes an estimated $6 million to $40 million in losses every year. The highest incidence of SDS is generally in years with cool, rainy weather during the growing season. Once found only in the southern states, SDS appears to be spreading through Illinoisand Iowa. "Fungicides don't provide any known benefits. Resistant varieties appear to be the only known solution," said Myers. "As SDS spreads, it becomes more important for farmers to plant the most resistant varieties available. Farmers recognized early on that they had to deal with this before it got worse, and they've been supportive of this research."
Myers is part of an SIU-C team that includes other plant breeders and geneticists, a molecular biologist and a microbiologist. With a broad base of expertise, they can address soybean disease problems from the laboratory and the field. The team is looking for genetic keys to resistance and genetic material that may be used in breeding programs. Every year, they also evaluate the performance of commercial and experimental varieties.
In addition, the team is studying how the disease develops in the plant and in the field. The C-FAR funds allowed the team to expand the epidemiology component of the project. Through this work, researchers will gain a better understand of how the SDS pathogen, Fusarium solani, interacts with the soybean plant. Findings could help the team increase efficiencies of breeding efforts, or might lead to management recommendations for limiting the spread of infection or dealing with problems after infection occurs.
Testing for SDS and soybean cyst nematode resistance is an important component of the research program. Each year, the team collects data on 400 to 500 commercially available varieties and germplasm that may make up future varieties. To date, no varieties have shown immunity to SDS, Myers said, but a few varieties have some level of resistance. Yearly results are shared with farmers, seed companies, the Cooperative Extension Service and others through tours and publications.
The SIU-C team is funded in part by the Illinois Soybean Checkoff Board and the North Central Soybean Research Program, which funds research in Illinois, Iowa, Missouri and Arkansas. Last year, the SIU-C team released eight germplasm lines with SDS-resistance genes and two new soybean varieties for commercial production.
Related C-FAR Research In other soybean breeding research, SIU-C researchers are measuring eight phytoestrogens in varieties and crosses, with a goal of using genetic technologies to alter the content of phytoestrogens in soybeans.
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