Mechanisms of Plant Electrophysiology - Electro-Horticulture - page 72

Cells are Electrical! Illustration of a Cell Having a Net Negative Charge
Goldsworthy also made significant progress in developing theories as to what happens
electrically within the cellular structures of plants. He knew that the flow of ions across
cells was akin to the flow of electrons moving through a wire, creating what we know as
electrical current . In this, he thought that they played a major role in plant development 11 .
Taking the ionic flows discussed above to a deeper level of understanding, let's begin
by discussing how voltage and current relate to cells. First, the difference in ionic
concentrations across a barrier such as a cell membrane is called an electrochemical
gradient , also known as a membrane potential . An electric field gets established between
both sides of the barrier when there is a difference in ionic concentrations. If there aren't
anydifferences,thenitissaidthatthereisnomembranepotential(orthemembranevoltage
is zero) because everything is in equilibrium.
When electric fields are present, which are most of the time since a cell is rarely, if
ever, in equilibrium with its environment, they play a major role in the operation and
upkeep of plant biology. They do so by having a critical role in the creation of electrical
or chemical-based signals used throughout the plant. Scientists like Goldsworthy and his
research associates have suggested that these signals are used in the communications of
messages notonlywithinasinglecell,butalsoacrossmanymultiples ofcells.Infact,they
have experimentally determined that fluctuating cellular electric fields can cause signals to
spread throughout the entire plant 12 . This will be discussed in more detail shortly.
Marinesco 13 , a French biochemist, found that the flow of ions in the plants' capillary
systems can produce electricity, too. In one experiment, he measured the voltage between
the roots of a plant and a point in the stem just above ground level. He found the voltage
to be approximately 0.4 volts. Thus voltages can be found not only across cell boundaries,
but also any location along the flow of ionic substances within a plant. It's interesting
today that experimenters are starting to even look at plants as living batteries for powering
remotely located devices, in lieu of using solar panels.