permaculture

["Lawrence F. London, Jr." <lflj@intrex.net>]

<http://www.nytimes.com/2008/04/01/science/01obshoc.html?_r=1&ref=science&oref=slogin>
Some people think that giving their houseplants an occasional talking-to is a good thing. But how about a little shock 
treatment?
Sub-lethal Levels of Electric Current Elicit the Biosynthesis of Plant 
Secondary Metabolites (Biotechnology Progress)

Researchers at the University of Arizona and the Samuel Roberts Noble Foundation in Oklahoma report that a small 
electric current applied to certain plants can stimulate the biosynthesis of chemicals with antifungal and other 
properties, without harming the plants. The finding, published in the journal Biotechnology Progress, suggests a new 
route to producing compounds with potential uses in research or in production of pesticides or medicines.

As with animals, plants synthesize higher levels of some chemicals in response to microbial infection. Researchers have 
tried to stimulate the controlled production of these chemicals using “elicitors” — either biological ones like cells or 
cell parts, or nonbiological ones like chemicals, ultraviolet light or ultrasound. The problem with most of these 
approaches is that they either harm the plants or yield compounds that then must be separated from the elicitor.

Hans VanEtten and Evans Kaimoyo of the University of Arizona and colleagues applied a low-level direct current (30 to 
100 milliamperes at 8 to 24 volts) to pea plant roots and found that the plants produced levels of pisatin, an 
antifungal compound, 13 times as high as those of untreated plants.

They say it is unclear how electricity increases such biosynthesis. But regardless of the mechanism, they say that by 
using plants that are growing in a hydroponic medium, it should be relatively easy to “harvest” the chemicals as they 
are produced.