Tomatoes that are eaten by insects use electrical signals to send an alert to the rest of the plant, similar to the way our nervous system warns of damage.
The messages appear to help the plant organize forms of defense such as releasing hydrogen peroxide, a reactive chemical that fights microbial infections of damaged tissues, according to a study. published in the journal Frontiers in Sustainable Food Systems.
The nervous system: are we men or tomatoes?
The human nervous system, you know, uses specialized cells called neurons to send electrical signals between different parts of the body. Plants lack neurons, but they have a “conducting system”: long, thin tubes called xylem and phloem to move the sap between the roots, leaves and fruits. The charged ions flowing in and out of these tubes can propagate electrical signals around different parts of the plant in a similar way to neurons, although much less is known about the process in plants than in animals.
Previous work found that physically damaged leaves in tomatoes send electrical signals to other leaves. In a new studio, Gabriela Niemeyer Reissig from the Federal University of Pelotas in Brazil and his colleagues studied whether this could happen with fruit.
A systematic review
The research team studied small plant of cherry tomatoes (tomatoes are a fruit, botanically speaking) by placing them inside Faraday cages, which block external electric fields. On the surface of the tomatoes, then, he placed the moth caterpillars helicoverpa armigera.
Electrodes placed in the stems of tomatoes are the focus of the study. They showed that electrical activity patterns changed during and after the caterpillars started eating. They also varied depending on whether the fruits were ripe or green. “The electrical activity of the fruit is constantly changing every second,” he says Niemeyer Reissig. “We can find a distinct pattern in the electrical activity when an insect attacks.”
There was also an increase in levels of hydrogen peroxide produced by intact fruit and leaves on an attacked plant. “This is probably to avoid microbial infections of damaged plant tissue. Another hypothesis is that it is a strategy to cause cell death in the affected region, preventing the spread of pathogens,” the authors say.
