Value-added Soybeans to Save Money and Environment
Low-phytate soybeans could reduce environmental pollution from livestock industry
Virginia soybean producers harvest more than 15 million bushels of soybeans each year, contributing between $75 million and $100 million to the state’s economy. Although conventional soybeans are the most economically important row crop in Virginia, about 75 percent of their total phosphorus content is in a form that cannot be readily digested by livestock, the No. 1 consumers of domestically grown soybeans. Livestock producers must either pay for dietary supplements that allow swine and poultry to process the extra nutrients or leave indigestible phosphorus in their livestock feed and risk polluting ecologically sensitive environments such as the Chesapeake Bay Watershed.
M.A. Saghai Maroof, professor of crop and soil environmental sciences, hopes the development of lowphytate soybeans will not only allow livestock producers to save money they would have spent on dietary supplements but also cut phosphorus pollution at
the source. “This in turn reduces the phosphorus content put back into the environment,” Maroof says.
For decades, developing a soybean line with a digestible form of
phosphorus instead of phytate seemed like an impossible feat. Soybeans are naturally high in phytate, and genetic engineering is not an economically savvy option because some countries, such as Japan, forbid the sale of genetically modified crops. Maroof and his colleagues found another way.
“We have discovered a soybean that is naturally low in phytate,” Maroof says. “Because the soybean we found does not have a high yield, we are combining a conventional approach to crop breeding with genomics tools to accelerate the development of high-yielding, low-phytate soybeans with normal emergence.”
Virginia Tech is the only university with this line of low-phytate soybeans. Katy M. Rainey, assistant professor of crop and soil environmental sciences, and Elizabeth Grabau, professor and head of plant pathology, physiology, and weed science, are working with Maroof to construct soybean chromosomal maps to determine the locations of low-phytate genes from various sources. The United Soybean Board funds their research through producer-supported soybean checkoff dollars.
“We are identifying molecular markers that are associated with low-phytate genes and use these markers to aid their transfers into elite cultivars,” Maroof explains. “This technique is commonly referred to as DNA fingerprinting or marker-assisted selection.”
Low-phytate soybean cultivars might not be commercially available for several more years, but Maroof is optimistic. The group is currently conducting a collaborative feeding trial for poultry and pigs in conjunction with the University of Missouri. Soybeans derived from the research at Virginia Tech were sent to a Canadian processing
company and then shipped to Missouri for livestock testing.
Maroof has other research programs on soybean improvement under his purview, too. His laboratory has led a project funded by the U.S. Department of Agriculture to modify techniques that
other researchers have used to isolate genes controlling disease resistance in tobacco and mustard weed and apply them to soybeans in order to develop disease-resistant cultivars. By sorting through about 30,000 soybean genes with molecular marker technology to find specific genes associated with disease resistance, researchers in Maroof’s laboratory are helping other scientists target their soybean breeding efforts. His laboratory is also involved with two multi-institutional projects funded by the National Science Foundation with the ultimate goal of developing more durable disease-resistant soybeans.
In addition, Maroof, Rainey, and their colleagues are trying to develop a soybean line with decreased levels of stachyose and other undesirable sugars. According to Maroof, this ongoing project involves “the identification of the chromosomal regions containing the genes that control the more useful type of sugar.” In other words, researchers are hoping to replace the undesirable sugars with sucrose to produce specialty soybeans with more protein, more calories, and more metabolizable energy than conventional ones.
“Although most of the soybeans in the United States are crushed into soybean meal for livestock, there is a multi-billion dollar soyfoods industry that produces tofu, soy milk, and other products,” Maroof says. “When we increase the level of metabolizable energy,this also improves the taste and, therefore, adds value to soybeans, which have been shown in recent years to have anti-cholesterol and anti-cancer properties.”
Interestingly, Virginia Tech researchers are working to develop high-sucrose soybeans using the same low-phytate soybean line they originally discovered. “The low-phytate trait, along with the low levels of sugars with undesirable characteristics, addresses two major concerns of the swine and poultry industries and should result in increased demand for soybeans and greater profit for producers,” Maroof says.