Researchers make breakthrough in controlling soybean cyst nematode

Technology has reduced nematode population in studies by as much as 85%.

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 by causing it to die or, at the very least, lose the ability to reproduce.

“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 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 found that the technology has reduced the nematode population in greenhouse studies by as much as 85%.

“The next question for us is: With our technology, can we enhance the germplasm that is already available for soybean breeding? We also have several other genes we’ve looked at,” Trick said. "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 indicated 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 1 in. long.

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

Trick noted, “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.

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 added.

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

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