Tomatoes send out ‘warning signals’ when attacked by insects

PELOTAS, Brazil — Tomatoes send out an electric “warning” signal to the rest of the plant when insects attack, a new study reveals. The alarm system is so sensitive, even the tiny footsteps of a caterpillar can set it off.

A team from Brazil says this system triggers the release of defense hormones to help protect the leaves and stem of tomato plants. Although some may find it funny when green thumbs talk to their plants, the latest findings add to evidence that plant really do have “feelings” – just like humans.

“What we found is that fruits can share important information such as caterpillar attack–which is a serious issue for a plant–with the rest of the plant, and that can probably prepare other parts of the plant for the same attack,” says first author Dr. Gabriela Niemeyer Reissig from the Federal University of Pelotas in a media release.

Using AI to reveal tomato signals

The study finds foul-tasting chemicals are let out by stalks, leaves, and branches — making them less appealing to hungry bugs. Tomatoes transmit their electrical tip-off through sap. The vitamin-rich water flows into the fruit, boosting growth. However, scientists have now discovered there’s also communication in the opposite direction going back to the plant.

“Since fruits are part of the plant, made of the same tissues of the leaves and stems, why couldn’t they communicate with the plant, informing it about what they are experiencing, just like regular leaves do?” Dr. Niemeyer Reissig adds.

In experiments, the team placed tomato plants in a Faraday’s cage. This is a mesh-like structure that shields contents from static electric fields. Electrodes at the ends of branches measured the electrical responses after the hanging fruits were attacked by caterpillars for 24 hours.

Researchers also used machine learning (or artificial intelligence) to identify these patterns. They found a clear difference between the signals before and after the insect onslaught. Biochemical sensors also showed an increase in the production of defensive chemicals like hydrogen peroxide, even in parts far from the damage.

The study in Frontiers in Sustainable Food Systems provides the first “big picture” overview of a plant’s electrical signals.

The results could lead to the development of improved farming techniques and help feed the world. Estimates show that humans will need to produce about 50 percent more food in the same land area by 2050 to cope with a population of 10 billion individuals.

Plants are getting a ‘feel’ for their surroundings

Dr. Niemeyer Reissig wants to see if the phenomenon holds true for other plant species as well as different types of threats. She says AI technology can answer these and other questions. It opens the door to more environmentally friendly insect control in agriculture.

“If studies like ours continue to advance and the techniques for measuring electrical signals in open environments continue to improve, it will be possible to detect infestation of agricultural pests quite early, allowing for less aggressive control measures and more accurate insect management,” the study author concludes.

“Understanding how the plant interacts with its fruits, and the fruits among themselves, may bring insights about how to ‘manipulate’ this communication for enhancing fruit quality, resistance to pests and shelf life after harvest.”

Recent research in the United States has discovered that plants have a sense of touch and can “feel” their fruit and leaves being picked. Another study reveals that shrubs communicate with each other about bees and other pollinators or predators using chemical messages.

SWNS writer Mark Waghorn contributed to this report.


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