London, March 29 : A new research has revealed that electric shocks can make plants produce more chemicals, which could be used to help increase yields of commercially useful biologicals.
According to a report in Nature News, researchers have long known that stressing plants can force them to take defensive action, often ramping up the production of protective chemicals that, for example, make them more resistant to insect attack.
A few milliamps of electricity can cause plants to increase synthesis of chemicals. These compounds often also have a pharmacological or commercial value, so the trick could be used to help increase yields of commercially useful biologicals.
Artemisinic acid, from sweet wormwood, for example, is used in malarial medications, and shikonin, from the purple gromwell plant, is used against skin infections.
It has become common practice to stress such plants into increasing their yields. This is usually done using physical stress elicitors, including bits of the micro-organisms that normally attack the plants, or irritants made from metallic compounds such as copper chloride.
Now, research groups at the University of Arizona in Tucson have found that the application of an electric current to the hairy roots of the poisonous herb Hyoscyamus muticus stimulated the production of the herb's toxin hyoscyamine.
This finding inspired Hans VanEtten from the University of Arizona, and his colleagues, to test sub-lethal levels of electrical currents on other plants, to assess electricity's potential to elevate chemical production.
His team exposed eight different plant species, ranging from Japanese pagoda tree seedlings to pea plants to weak electrical currents of 30 milliamps.
Seven of the plants increased their production of defensive chemicals. The average boost of chemical production was 20 times. One plant, a type of alfalfa, increased its chemical yield by 168 times.
These values are very similar to those achieved using chemical elicitors, and seem to have no lethal effects - just a negative effect on growth.
The treatment can even be used over and over again without the build up of any unwanted material.
According to VanEtten, "The fact that we can use electricity instead of toxic materials to elicit chemical production is very exciting because it means we get to look at how these chemicals form without having to constantly add and remove toxins from the system."
"This is a really novel and creative approach that I've never seen before," saod plant metabolic engineer Fabricio Medina-Bolivar from Arkansas State University in Jonesboro. The possibilities for using electricity with plants in this way are absolutely tremendous," he added.