Scientists have identified a new vulnerability in cyst nematodes’ communication with plant roots that could reduce the damage these parasites cause in soybeans and other crops, according to a study co-authored by an Iowa State University professor.
Researchers have pinpointed a single protein that appears to regulate dozens of chemical signals — known as effectors — used by cyst nematodes to manipulate plant cells and create a feeding site. These findings, published in Proceedings of the National Academy of Sciences, highlight a potential target for new control strategies.
“Now we have a validated target, a tangible molecular event involving a single transcription factor,” said Thomas Baum, distinguished professor of plant pathology, entomology and microbiology at Iowa State. “It’s a proof of concept that opens the door to various new ways of thinking about nematode management.”
The transcription factor, identified in both soybean and sugar beet cyst nematodes, plays a central role in initiating effector production. Without it, nematode infections are significantly reduced.
Nematodes rely on effectors to take over a plant root’s inner workings. After hatching in soil, the roundworms burrow into roots and inject these chemical messages to reprogram a plant cell. The goal is to transform one cell, and eventually neighboring cells, into a large, specialized feeding structure.
“The language they use is chemicals, not words,” Baum said. “Effectors deliver a message to a plant cell and it changes, turning into a cell type not usually found in a soybean root. Then all the neighboring cells change, and they fuse together to form a huge new organ whose sole function is feeding the worm.”
While nematologists have long studied effectors, targeting them has proved difficult because of redundancy; nematodes produce hundreds.
“You take one effector away and a nematode laughs and says, ‘I’ve got 10 more,’” Baum said.
The research team turned their attention to the source: the nematodes’ esophageal glands. Using RNA transcript data and genome sequences, they narrowed down key genes regulating effector production.
That led to a breakthrough in collaboration with Sebastian Eves-van den Akker at the University of Cambridge. His team identified a transcription factor, now named Subventral-Gland Regulator 1 (SUGR-1), that activates 58 different effector genes.
They also discovered that root signals, called effectostimulins, appear to activate SUGR-1.
“The most exciting thing for me about this paper is the picture it paints of a self-reinforcing cycle driving nematode infection of plants,” Eves-van den Akker said. “They break plant cells, sense some signals released and respond in a way which increases their ability to break host cells.”
Baum said these findings could influence real-world control methods. While current practices focus on crop rotation and partially resistant soybean varieties, genetic approaches could soon play a larger role.
Soybeans could be bred to produce RNA that interferes with SUGR-1, or chemical treatments could block the plant signals that trigger it.
“With nematodes, you don’t necessarily have to kill off every worm,” Baum said. “If I reduce infection by 40%, that’s a big deal. It would make a real dent in crop damages.”
The implications stretch beyond agriculture. Since nematodes are parasitic in animals too, this line of research could influence human and veterinary medicine.
Baum said his collaboration with Eves-van den Akker will continue.
“If you were to draw up the way you want to interact with a scientific collaborator, it would be just like this. You build on each other and freely share to make advances that help both camps,” he said.
Baum expects more discoveries ahead.
“SUGR-1 is just the first one that jumped off the page,” he said. “But we know there are others. This is only the beginning. There will be many targets.”
