May 11, 2004

SIUC Country Column: SIUC scientists develop SDS-resistant soybean

by K.C. Jaehnig

A high-yielding soybean that can survive a costly, rapidly spreading, incurable disease could be on the market in three to four years.

Scientists at Southern Illinois University Carbondale have developed a breeder-friendly soybean that, when crossed with conventional varieties, will produce a new breed of bean that can resist all known variations of the fungus that causes soybean sudden death syndrome, or SDS. Breeders can use it with all bean maturity groups without trading resistance for yield.

"It's the first soybean ever made available to the growers via the breeding companies that has a full stack of resistance genes -- six different ways of stopping the disease," said David A. Lightfoot, who headed the SIUC development team.

"It's very, very unlikely to fail. Even when we've had nasty conditions -- a real wet, cold spring with a really wet summer following -- this bean did OK."

ACCESS Plant Technology Inc., an 8-year-old technology-transfer company headquartered in Plymouth, Ind., recently licensed the patent rights to the bean from the University, which it is offering to commercial breeders this growing season.

The prospect of a resistant bean -- even one that's three to four years in the future -- is good news for American farmers who lose between $200 million and $400 million to the disease each year, depending on weather. In Illinois, the nation's No. 1 soybean producer, SDS losses total between $40 million and $80 million annually -- again, depending on weather.

"SDS is the most weather-dependent of all soybean diseases, so you need a five-year window to see national trends," Lightfoot said.

"Looking through that window, we found losses to SDS have been doubling every five years."

And it could get worse. Although SDS has traditionally plagued farmers in temperate regions, plant pathologist X.B. Yang of Iowa State University reports that the fungus has adapted to northern soils, Lightfoot said.

"That means the potential for ever-increasing losses in the future is huge," he said.

While genes underpin the SIUC bean's resistance to SDS, it is not a genetically modified organism, or GMO, Lightfoot stressed.

"We're using genomics methods that rely on natural variations within crops and then capturing the most valuable genes with DNA marker selection," he said.

Beans bred from this line will still be able to contract SDS, but they won't get it as soon or as severely as current varieties do. This, as a disgraced domestic diva used to say, is a good thing.

"If you try to deprive something of its biological life, it will come back and mutate into a more virulent form," Lightfoot said.

"So you don't try to kill off the fungus. The happy balance is what you shoot for, though with SDS, we'd like to tip that balance more in favor of the plant."

If new varieties bred with the SIUC bean come down with the disease, it won't set in until at least 21 to 45 days after planting -- susceptible varieties can get it in as little as seven days. That delay in infection rates means more money for farmers.

"One to two weeks' delay can make a difference of 20 to 30 percent in your yield," Lightfoot said. "That's been proven over and over again with many different pathogens."

Breeders who want to use the SIUC bean will pay a licensing fee.

"This will probably be a shock when they're used to getting publicly released lines for free," he said.

But because of the role technology plays, using this bean should prove cheaper in the long run.

"The old way of breeding involved making as many crosses as possible, and it took a long time to get the best of the best," Lightfoot said.

"Here, they'll focus on a few crosses, confirm that the genes are where they're supposed to be with a quick, cheap greenhouse assay and then be able to release a super-resistant cultivar -- all within three or four years."

Lightfoot has been working on developing SDS-resistant soybeans since he came to SIUC in 1991. Funding sources for his research have included the Illinois Soybean Board and the United Soybean Board. The Office of Research Development and Administration's technology transfer program managed the patent process and negotiated the license agreement.

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