— Plants can sense and react to temperature changes, harsh winds, and even human touch. But can they hear?
They have no specialized structure to perceive sound like we do, but a new study has found that plants can discern the sound of predators through tiny vibrations of their leaves — and beef up their defenses in response.
It is similar to how our own immune systems work — an initial experience with insects or bacteria can help plants defend themselves better in future attacks by the same predator. So while a mustard plant might not respond the first time it encounters a hungry caterpillar, the next time it will up the concentration of defense chemicals in its system that turn its once-delicious leaves into an unsavory, toxic meal.
Now, biologists from the University of Missouri have found that this readying process, called “priming,” can be triggered by sound alone. For one group of plants, they carefully mimicked what a plant would “hear” in a real attack by vibrating a single leaf with the sound of a caterpillar chewing. The other group was left in silence.
When later faced with a real caterpillar, the plants that heard chewing noises produced a greater amount of insecticide-like chemicals than the silence group. They also seemed able to pick out those vibrations signaling danger; playing wind noises or insect mating calls did not trigger the same chemical boost.
Although the mechanism of how plants can discern sounds is not known, a deeper investigation could lead to advances in agriculture and natural crop resistance — as opposed to spraying costly and harmful pesticides.
“We can imagine applications of this where plants could be treated with sound or genetically engineered to respond to certain sounds that would be useful for agriculture,” said study author and biologist Heidi Appel.