Soybean Cyst Nematode: New Technology Will Significantly Reduce Populations

    Female soybean cyst nematodes visible on soybean roots. Photo: Iowa State University

    A microscopic worm that has been a giant pain for U.S. soybean farmers may soon find farm fields unpleasant places to be.   

    Kansas State University researchers recently announced a significant breakthrough in controlling the spread of the soybean cyst nematode, a parasitic roundworm that the U.S. Department of Agriculture estimates has reduced yearly returns in soybeans by $500 million and yields by as much as 75%.

    Plant geneticist Harold Trick said the university has received a patent for the technology that essentially “silences” specific genes in the nematode, causing it to die or, at the least, lose the ability to reproduce.

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    “We have created genetically engineered vectors [or DNA molecules], and put those into soybeans so that when the nematodes feed on the roots of the soybeans, they ingest these small molecules,” said Trick, who has worked closely with plant pathologist Tim Todd on this project.

    Previously, the scientists studied the nematode to learn which genes are crucial to the parasite’s survival. The new vectors target those genes and shut them off, a process called gene silencing.

    “The nematode will either lose fitness to live, or its ability to produce will be greatly reduced,” Trick said.

    So far, the scientists have found the technology has reduced the nematode population in greenhouse studies by as much as 85 percent.

    “The next question for us is, with our technology, can we enhance the germplasm that is already available for soybean breeding,” Trick said. “We also have several other genes we’ve looked at. Is it possible to combine all of these traits into one soybean variety and have an even greater reduction than 85%.”

    The soybean cyst nematode is known to be present in at least 29 states, as well as South America and Asia. Previous work indicates that once it is present in soil, it can never be fully eliminated. The parasite is so small that if 32 of the largest worms were laid end-to-end, they would measure only one inch.

    Once they feed on a soybean plant, it takes just about 48 hours for them to penetrate the roots. After about a week, they can rupture through the plant tissue.

    “We’ve been focusing on the soybean cyst nematode, but we also think that there are a lot of similarities in the genes we selected to other nematodes, such as the root knot nematode (which affects grasses, fruits, vegetables and weeds),” Trick said.

    The technology will take many years to reach producers’ fields, Trick said.

    “This is a genetically engineered product,” he said, noting that it will undergo intense regulatory scrutiny before it can be made commercially available.

    “We hope to eventually take the traits we’ve discovered and move those over into Kansas-adapted cultivars so that we can deploy this in farm fields,” he said.

    The work is funded by the National Institute of Food and Agriculture through the Agriculture and Food Research Initiative (AFRI). Funding and support has also been provided by the Kansas Soybean Commission, U.S. Soybean Board and the North Central Soybean Research program.

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