Aspirin in the air

Aspirin, by Chaval Brasil.

Scientists testing the atmosphere above a walnut grove in California found aspirin in the air.

Actually, they found a chemical variant of aspirin, methyl salicylate (MeSA), which you may not have heard of but you’ve certainly smelled and tasted. It’s also known as oil of wintergreen, ingredient of Ben-Gay liniment and wintergreen Life Savers. (It’s both the flavoring in those Life Savers and the reason they sparkle when you chew them).

Scientists from the National Center for Atmospheric Research say that plants use MeSA as a warning chemical, puffing it into the air to communicate “ecosystem-level stresses” to other plants.

Researchers had found earlier that tobacco plants release MeSA into the air when they are infected with a virus. The NCAR scientists found it above the walnut grove when temperatures got cold enough to damage leaves. The signal may give undamaged plants a head start on beefing up their defenses.

Aspirin-like chemicals seem to trigger a plant’s Systemic Acquired Resistance response, which is essentially the plant version of an immune system. The SAR response helps plants both to resist disease and to recover from it.

Willow bark. Photo by joebaz.

Aspirin is better known, of course, for its effects on disease symptoms in people. Its variant salicylic acid was known as a pain reliever and fever reducer long before it was chemically formulated in 1853 (as acetylsalicylic acid) or manufactured in pill form (by Bayer in the 1890s).

The bark of willow trees contains a lot of salicylic acid, and was used by Native Americans and ancient Sumerians, to name a few. The flowering shrub called myrtle and, of course, wintergreen, are also sources of pain relief preparations.

But with this new information about how plants use MeSA, people can now make use of the chemical in another way. Farmers could use the MeSA signal much like plants do – to detect stress or disease before it spreads. Since the MeSA signal appears before there is any visible damage to the plants, a farmer who monitors the signal can take action – applying pesticides, for example. “The earlier you detect that something’s going on, the more you can benefit in terms of using fewer pesticides and managing crops better,” is how one of the scientists put it.

• Journal article: Chemical sensing of plant stress at the ecosystem scale. [by the way – props to the journal that published this work, Biogeosciences. It’s an open-access journal, and you don’t have to have a subscribing library or a bajillion bucks to go read it.]