Aspirin Agent Aids Plants Against Virus

Yet another extraordinary ability of the active ingredient in aspirin, salicylic acid, has just been identified by plant scientists working at the University of Cambridge, researchers heard today, Monday 29 March 2004, at the Society for General Microbiology’s meeting in Bath.

“We all recognise its bitter taste and pain-killing abilities, but the importance of the active ingredient of aspirin, called salicylic acid, is even greater”, says Dr John Carr of the Department of Plant Sciences at the University of Cambridge. “We now know that salicylic acid is used by plants to fend off attacks by viruses, bacteria and fungi”.

The parent molecule of aspirin turns out to be made by all plants, not just willow trees and meadowsweet, and is used as an alarm signal when the plant is attacked. The acid acts as a messenger to help mobilise resources from uninfected parts of the plant, resist the microbes and respond even more effectively against further attack.

“Salicylic acid stimulates the plant cells to produce chemical defences called enzymes which directly attack the bacteria and fungal cells, but these defences cannot affect viruses”, says Dr Carr. “We have now discovered that salicylic acid triggers three other distinct mechanisms to fight off viruses. It stops the viruses copying themselves, it stops the virus moving through the plant and it triggers a self destruct mechanism in the viruses’ genetic material, called RNA”.

The abilities to stop viruses moving and reproducing are governed by changes in free radical levels inside the mitochondria, the cell’s energy generators. These changes are under the control of a plant enzyme which also protects the plant against poisonous levels of free radicals, and which can warm up flowers to attract insects.

“These findings have filled a gap in our knowledge of how salicylic acid works to aid resistance. This in turn will help us develop new ways to protect crops and plants, either naturally by boosting their natural resistance, or through genetic modification”, says Dr John Carr.