Ohio State University researchers have identified new soybean varieties that exhibit both partial and complete resistance to a pathogen responsible for severe production losses.

"If we do find a novel resistant gene, we're going to be breaking open the champagne," said Anne Dorrance, an OSU plant pathologist at the university's Ohio Agricultural Research and Development Center (OARDC). "This would be a major find."

Dorrance and OSU plant pathologist Fritz Schmitthenner evaluated 1,015 soybean plant introductions -- varieties found in other countries -- and found that 32 exhibited complete resistance and 130 high levels of partial resistance to Phytophthora. All of the varieties originated in South Korea and were obtained from the U.S. Department of Agriculture Soybean Germplasm Collection in Urbana, Ill.

Phytophthora sojae causes soybean root rot and is a major problem in Midwest states that have heavy clay soils. Torrential rains saturate the soil producing areas with standing water, which provides an outlet for the pathogen to infect plant roots. The fungus grows in the plant roots and into the plant stem, and eventually kills the plant.

"The timing right now is perfect to find a new gene and get it out in the market," Dorrance said, because Phytophthora is slowly adapting to current soybean resistant genes.

"We are continuously putting pressure on those resistant genes. Eventually they will no longer hold up to the pathogen," she said.

The next step in research is to identify the gene in the South Korean soybean varieties showing resistance to Phytophthora and introduce it into current commercial varieties. The hope is that those varieties will carry the resistant gene, Dorrance said.

"If we do find the gene, it may be five or six years before we can get out a completely resistant variety, and four or five years before we could release a partial-resistant variety," she said.

OARDC horticulturists Steve St. Martin and Ron Fioritto are conducting the genetic work, scheduled for completion by next spring.

The study is available online at www.ars-grin.gov/npgs/.

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