When poultry animals are being slaughtered for food, we assumed that they might cry out in pain. But have you ever wondered about plants, if they would understand the circumstances where they are about to be eaten? The answer from most people is that it is impossible for plants to do so, but research has found that plants do ‘hear’ themselves being eaten.
Researchers from the University of Missouri (MU) have found that a small flowering plant, Arabidopsis thaliana, is able to hear the chewing of their leaves loud and clear when they are eaten by caterpillar. As a defense, the plant would respond[ihc-hide-content ihc_mb_type=”show” ihc_mb_who=”2,3,5″ ihc_mb_template=”1″ ] to the attack by launching a chemical defense. In the past, research has been performed whereby plants were being studied for their association with musical sounds. It was found that music does influence the growth in certain plants. Even though it is known that plants are able to detect sound, but the reason why they are able to do so remains a mystery.
The study was performed by placing a caterpillar on Arabidopsis, a small flowering plant that is related to cabbage and mustard. Then, the vibrations generated by the chewing of the leaf are being recorded. A tiny piece of reflective tape were being placed on the leaf of the plant and with a laser beam, the leaf’s movement produced by the chewing of the leaf were then recorded.
Next, two sets of the plant, Arabidopsis are used in which one is being played with the vibrations of the caterpillar chewing on the leaves while the other with only silence. After two hours, the cabbage butterfly caterpillars are being introduced to the plant to feed on both sets of the leaves. Both sets of plants were given 24 and 48 hours to respond to the attack and then the leaves are being harvested.
The researchers found out that for the set of plant previously being exposed to the feeding vibration releases higher amount of mustard oil. This oil is a chemical that is unappealing to the caterpillars.
According to Daily Mail, Heidi Appel, a senior research scientist in the Division of Plant Sciences in the College of Agriculture, Food and Natural Resources and the Bond Life Sciences Center at MU said that previous research has investigated how plants respond to acoustic energy, including music.
“However, our work is the first example of how plants respond to an ecologically relevant vibration. We found that ‘feeding vibrations’ signal changes in the plant cells’ metabolism, creating more defensive chemicals that can repel attacks from caterpillars.”
In another set of experiments, two other types of vibrations were being tested to determine if the plants chemical defense increases only in response to the chewing vibrations, or if they also respond to any other types of vibrations. The vibrations were wind induced vibrations and the sound from a non-harmful insect. In this experiment, the results showed that the plant did not increase their chemical defense when being exposed to the two other types of vibrations.
Based on the news report from the Daily Mail Rex Cocroft, professor in the Division of Biological Sciences at MU said: “What is remarkable is that the plants exposed to different vibrations, including those made by a gentle wind or different insect sounds that share some acoustic features with caterpillar feeding vibrations did not increase their chemical defenses.
‘“This indicates that the plants are able to distinguish feeding vibrations from other common sources of environmental vibration.”
A grant has been awarded by the National Science Foundation to extend this project and the next step of this research is to determine how other types of plants would respond to the sound of their predators. The researchers are also looking forward to precisely determine the features of the sounds that are able to change the plant’s defense system.
From the MU science blog, Decoding science, Appel said ‘Once you understand these things you can mess around with it in plant breeding through conventional methods or biotech approaches to modify plants so they are more responsive in the ways you want to make them more resistant against pests. That’s the practical application one day.’
Frank Telewski, a tree expert in investigating the perception of mechanical stimuli in plants said that he was very impressed with the study as reported by the Washington Post.
“It might be practical to see how loud you would have to play speakers in a field to get plants geared up to fight against an insect,” he said.
“This might be one way to fight off an insect attack without spending a lot of money on pesticides,” he quipped.
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