A natural defense that helps plants ward off insect predators, discovered at Washington State University, could lead to better crops and new treatments for cancer and Alzheimer’s disease.

Sachin Rustgi, adjunct assistant professor at the WSU Department of Crop and Soil Sciences, detailed the interaction of enzymes called proteases and their inhibitors, along with the role they play in plant health and development, in the journal Proceedings of the National Academy of Sciences. The discovery could pave the way for advances in medicine and agriculture.

“By understanding this relationship, we can regulate it for our health and agricultural needs,” Rustgi said. “We can make enzymes available, or trap them when they’re not beneficial.”

Rustgi explored the relationship between a protease called RD21 and its inhibitors, Serpin1 and WSCP, in plants. “When they first start growing, young plants are quite vulnerable,” said Rustgi, who first set out to study seedling defense with colleagues at Grenoble Alpes University and Jean Monnet University in France.

They found that when a seedling emerges from soil, inhibitors shut down and protease levels rise. When an insect tries to eat the plant, the protease attacks its digestive enzymes, causing the insect to seek a different meal.

Protease inhibitors also influence plant resistance to disease and drought.

“Diseases that kill plants can be avoided by over–expressing these inhibitors,” said Rustgi. Proteases can also cause crops such as wheat, barley and corn to mature faster and avoid late–season drought.

Better understanding of protease activity could also improve human health, Rustgi said. His findings bring insights into cancer progression and could lead to new therapies for cancer and other diseases.

“These proteins are similar in structure in animals and plants,” he said. “Most medicines for cancer and aging diseases are protease inhibitors. Understanding how these proteins interact could lead to artificial inhibitors and ultimately to safer medicines.”

Rustgi, currently at Clemson University, researched this natural defense system while working with co–author Diter von Wettstein, the R.A. Nilan distinguished professor at WSU.