Pest-resistant Soybeans Grow Out of MAES Lab

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Dechun Wang (view larger image)

Two lines of pest-resistant soybeans painstakingly developed by an MABR scientist promise healthier harvests for growers and a little green for the university, too.

“Sparta—the Soybean Aphid Shield” is the new trade name for genetics developed by Dechun Wang, MABR soybean breeder and crop and soil sciences researcher. He tested approximately 2,000 strains of soybeans for their ability to withstand aphids and isolated four with different resistant genes. From those he developed germ plasm and bred varieties suited to Michigan’s short growing season.

“The final goal,” Wang said, “would be to have one variety that has all those resistant genes,” maximizing protection against various biotypes of aphids and perhaps other pests such as Japanese beetle.

Soybean aphids suck plant sap and secrete a sticky substance that promotes growth of sooty black mold. After they sprout wings, the aphids can speed the transmission of plant viruses. Fifteen generations of aphids can live on a soybean plant in the summer; the eggs overwinter on nearby buckthorn.

“In the field, we will inoculate a plant with just two aphids, and the entire plant will be totally covered by aphids in a few weeks,” Wang said. “It takes aphids just five days to produce more babies—aphids are born pregnant, so the regeneration cycle is incredibly fast.”

Soybeans have been cultivated in Asia for thousands of years but only since 1904 in the United States, where they’re mainly processed into animal feed and vegetable oil. Tiny soybean aphids, also native to Asia, were first identified in Wisconsin in 2000 and quickly spread to most soybean-growing areas until mostly controlled with chemical pesticides. Unchecked, aphids can reduce yield by 50 percent, but one pesticide application can increase production costs by 10 percent and also kill beneficial insects.

“Pesticides have really been our only answer until this new host plant material,” said Keith Reinholt, field operations director for the Michigan Soybean Promotion Committee (MSPC). His group has funded Wang’s research since 2002 with about $250,000 per year from grower assessment revenue, earning it first claim on licensing rights after MSU patented the resistance technology.

The germ plasm is generating interest among seed companies, which will use it to improve their varieties. The MSPC grower board will earn royalties from the sale of seed company varieties containing the trait. A portion of those will come back to MSU, which will in turn distribute royalties to Wang, the College of Agriculture and Natural Resources and the MSU Foundation.

“With one exception, all the major soybean genetics companies have licensed his germ plasm because the level of resistance to soybean aphids is very high,” said James Kells, chairperson of the Department of Crop and Soil Sciences. “We’re very excited about this technology, and we see great potential for commercialization and impact on soybean growers in Michigan and elsewhere in the United States.”

Wang’s research also is supported by the Michigan AgBioResearch.

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