Allergy-free soybeans

May 8 2006

Researchers have isolated two Chinese soybean lines that grow without the primary protein linked to soy allergies in children and adults. The two lines already are adapted to Illinois-like conditions and will be given away to breeders seeking to produce new varieties of allergy-free soybeans without genetic engineering.

Crop scientists at the University of Illinois at Urbana-Champaign and the USDA-Agricultural Research Service's Donald Danforth Plant Science Center in St. Louis screened more than 16,000 soybean lines kept in the USDA's National Soybean Germplasm Collection. The findings will appear later this year in the journal Crop Science.

The two soybean lines (PI 567476 and PI 603570A) contain virtually identical genetic mutations that do not contain the leading allergy-causing P34 protein, which consists of 379 amino acids, said Theodore Hymowitz, emeritus professor of plant genetics in the crop sciences department at the U. of I.

"We are releasing this information with no patents so that companies and breeders involved with soybeans can incorporate these two lines as quickly as possible," Hymowitz said. Companies in Japan, Canada and across the United States have been following the research effort, he added.

The research, which was funded primarily by the Illinois-Missouri Biotechnology Alliance, went through two stages.

First, using a specially developed immunochemistry approach, Hymowitz's post-doctoral assistant Leina M. Joseph examined 100 lines of soybeans per day for nine months from the UI-based collection. Seeds were crushed, treated and placed on a membrane for screening. A second screening using stronger antibodies and protein gels was done to confirm the absence of P34 in the two domestic lines, Joseph said.

After the two lines were isolated, seeds were sent to the Danforth Center for additional molecular analysis to determine why P34 was absent. Six identical genetic mutations were found in each, indicating the two lines may be related, Hymowitz said.

"The lack of the protein was confirmed by more-detailed two-dimensional protein assays," said Eliot M. Herman, a lead scientist at Danforth who probed the seeds with post-doctoral researcher Monica A. Schmidt. "We then isolated the gene responsible for the lesion, and we found there was a single significant change in the gene's sequence that likely produced a protein which could not be made as a stable product."

Herman discovered P34 in the early 1990s and in 2003 had successfully used a gene-silencing technique to create a soybean line in which P34 was "knocked out." However, because of public resistance to genetically modified products researchers have been seeking a more traditional approach. Because the newly identified lines occur naturally, they can be successfully crossed into other soybean lines "without any biotechnology-derived component," the researchers noted.

"Soybeans are slowly but surely increasingly being used in the foods we eat, and with that we are noticing an increase in the number of children and adults that have allergies to soybeans," Hymowitz said.

Currently, 6 percent to 8 percent of children are allergic to soy-based products, including infant formulas, while 2 percent of adults have had allergic reactions, which range from harmless skin reactions and gastrointestinal irritation to more serious facial swelling, shortness of breath, difficulty swallowing and fainting.

Avoiding soy products is becoming more difficult because of soy's use as fillers and components of many menu items. While people can read labels before preparing meals at home, avoiding soy at restaurants isn't as easy, Hymowitz said.