Up to 40% of global food crops are lost every year to plant pathogens. That figure, reported by Phys.org, frames the stakes behind a new study from the Boyce Thompson Institute, or BTI, in which researchers identified a natural compound that can prepare plants to fight off a wide range of threats without slowing their growth.
The compound belongs to a class of nematode pheromones called ascarosides. The study, published in Communications Biology, was led by professor emeritus Dan Klessig and professor Frank Schroeder of BTI, along with former BTI postdoc Dr. Murli Manohar and Uwe Conrath, a professor at RWTH Aachen University in Germany. Klessig, Schroeder, and Manohar are also co-founders of the BTI startup Ascribe Bioscience.
Nematodes are microscopic worms found throughout soil. They include many plant and animal parasites. Schroeder's lab had previously shown that nematodes produce simple glycolipids called ascarosides. From that work, researchers began asking whether other organisms could detect ascarosides as a kind of chemical signal.
"Because ascarosides were so consistently and specifically associated with nematodes, we wondered whether they could be perceived by other organisms as a 'molecular signature' of nematode threat," Schroeder explained. "In particular, we were curious whether ascarosides could affect plant immunity. We showed that, yes, plant immune systems do respond to ascarosides, though initially it wasn't clear what that response was."
One ascaroside in particular stood out during earlier studies: ascaroside 18, referred to as ascr#18. When plants were exposed to it, they showed increased resistance to bacterial, viral, fungal, and nematode pathogens. But the researchers found the response was not simply a standard immune activation.
When plants mount a full immune response, they divert energy away from growth and development. The BTI team found that ascr#18 did not trigger that kind of response. Instead, it put plants in a heightened state of readiness.
"Ascr#18 doesn't induce a full immune response but instead signals the plants to get ready, so that they can respond to pathogens more quickly and robustly," Klessig said. "It gives the plants immune memory without the fitness cost of immune responses."
The researchers describe this as immune priming, a concept they compare to how vaccines prepare the human immune system to respond rapidly to specific pathogens. The plant, in effect, is put on alert without burning resources on a fight that hasn't started yet.
The research has direct implications for food security. If ascr#18 or similar compounds can be developed into agricultural treatments, they could offer a way to protect crops from a broad spectrum of pathogens without relying on traditional chemical pesticides, and without the yield penalties that come from triggering full plant immune responses.
The BTI startup Ascribe Bioscience, co-founded by three of the study's lead researchers, is positioned to move this work toward practical application. The study adds to a growing body of research exploring how natural soil chemistry can be used to strengthen crops from the ground up.
