ISU researchers are taking steps to repel soybean cyst nematodes, thousands of tiny worms that feast upon soybean plants and cause a decrease in crop production.

Thomas Baum, associate professor of plant pathology, and colleagues Richard Hussey of the University of Georgia and Eric Davis of North Carolina State University have recently discovered a breakthrough in understanding how soybean cyst nematodes function.

Soybean nematodes are small worms that deprive the soybean plant of nourishment and use it for themselves, Baum said.

Plants are not just affected by one nematode, but thousands — a soybean plant will appear healthy until a certain level of nematode infection takes place, but the plant uses all of its energy toward the nematode and not toward producing beans, he said.

Baum said over the years, both the nematode and the plant survive, but crop production decreases — in addition, other major problems occur other than a decrease in crop production.

People often are not aware that nematodes continue to become worse until the farmers are not able to grow soybeans anymore, Baum said.

Identifying infected soybean plants so there is not a decrease in crop production is a difficult task, he said.

“The plants show no specific symptoms, so you must look at the plant’s roots to prove the nematodes,” Baum said.

The worms are about the size of a pinhead. This makes them difficult to detect by the naked eye, Baum said.

Through their recent discovery, Baum and his colleagues are one step closer to making nematode-resistant soybeans.

The research team has identified 60 proteins which the nematode injects into the plant to prevent the plant from defending itself.

“It has been a surprise to find 60 sequences,” said Thomas Maier, assistant scientist of plant pathology. “Now that we have identified the sequences that are important to nematode’s ability to affect the plant, we must focus on these sequences.”

Baum said as the team compared the sequences, they discovered that seventy percent of the proteins identified by the research team are unique.

“In collaboration of the research project, we have been sequencing the cDNA (gland cells) of nematodes at Iowa State University,” Maier said. “We have been making databases to compare against the sequences that already exist.”

Now the team must perform experiments to figure out how the secretions work, Baum said. The group already has two leads as to how the secretions break down the plant.

Baum said he suspects some proteins secrete enzymes that attack the nucleus by softening the cell wall.

Another hypothesis is that nematodes copy the plant’s signal transduction components, Baum said.

After 10 years of work on this recent breakthrough, Baum said he is confident a soybean plant will be made in the future that is nematode-resistant.

Now that the research team has identified all the secretions released into the plant, the next task is to find out what the secretions do.

“Within the group we have split up the 60 proteins,” Baum said. “Now we move forward.”