Study Shows Aspirin Blocks "Plant Pain"

Plants may not feel the pain of an injury as animals do, but they do have their own "alarm" reaction to tissue damage and, in an effect curiously similar to that in animals, this reaction can be short-circuited by aspirin and other similar drugs, according to a study recently published in The Journal of Biological Chemistry.

The study was authored by plant biologists Zhiqiang Pan of Arizona State University; Bilal Camara of the Institut de Biologie Moleculaire des Plantes, Strasbourg, France; Harold W. Gardner of the United States Department of Agriculture; and Ralph A. Backhaus of Arizona State University and appeared in JBC's July 17 issue.

Aspirin, the researchers discovered, interrupts the production of a key compound that plants produce in response to physical injury in much the same way that it interrupts in animals the production of the compound that tissue produces when it is hurt, leading to the pain reaction.

The function of aspirin in animals is to block the production of prostaglandin, which triggers swelling and pain. Aspirin binds to the active site of the enzyme that is critical to producing prostaglandin.

"It essentially renders the enzyme dead and prevents prostaglandins from building up and creating a reaction," said Backhaus.

In plants, aspirin blocks the production of jasmonic acid by similarly binding a critical enzyme.

"Jasmonic acid is a hormone that is made when plants are in distress. It signals the production of plant-defense compounds -- it works a little like a shot of pain, warning the plant that it is under attack. It can also volatilize and warn nearby plants, a chain reaction that's like a warning signal to other plants. This seems to particularly apply to insect attack, as the alerted plants then produce specific compounds that produce insect gastro-intestinal distress.

"It turns out that aspirin will suppress the formation of this compound (jasmonic acid), so it suppresses the warning signal, like it suppresses pain in animals," Backhaus said.

While humans may want to tune out the pain "alarm" signaling that their body is under distress, it is hard to see what benefit aspirin's suppression could have in the plant reaction.

Unless you're a hungry insect ransacking a patch of plants, that is, and you want to shut off the neighborhood's burglar alarms... and have lunch.