Plants Hear Their Parts Being Eaten

According to a group of researchers at the University of Missouri in Columbia, Missouri, while plants don’t have what we think of as ears, a flowering plant similar to mustard, Arabidopsis, may very well recognize the sounds of a hungry caterpillar. Furthermore, once the plant acknowledges the munching menace it secretes other oils that caterpillars do not enjoy.

Heidi Appel, lead researcher of a new study published in Oecologia, said: “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.”

Arabidopsis,/Image: ABRC

While it was previously known that plants respond to touch and even to the wind, the UM group’s research revealed that plants can actually be selective in terms of what sounds to which they choose to notice. The investigative team played various recordings for the plants and noted their reactions.

The vibrations of the caterpillar’s munching were the only sounds to cause the plants to excrete extra mustard oil. Recordings of wind and other vibrations received no such response from the plant.

Rex Cocroft, study co-author, stated: “This indicates that the plants are able to distinguish feeding vibrations from other common sources of environmental vibration.” Cocroft and company believe that knowing more about how plants deal with “ecological threats” could aid botanists in creating plants with better “defense mechanisms.”

Appel added: “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.”

The group also hopes to determine how the plants detect vibrations. Appel and Cocroft believe it has something to do with a protein named mechanoreceptors. Mechanoreceptors react to distortion or pressure although details remain a mystery. Appel concludes: “Finding that out is our next step.”