When a beetle larva bites into the leaf of a goldenrod plant …. [t]he bite damages the goldenrod …. causing it to launch molecular defenses against the insect and to emit a concoction of chemicals that change the physiology of goldenrod plants nearby. It’s as if the plants are communicating about the invader, Ashley Yeager, an associate editor at The Scientist reports.
The notion that plants communicate was controversial until the end of the 20th century. Biologists first argued that trees and plants could “talk” to one another in the 1980s, but data supporting the idea were dismissed by many researchers as statistically sketchy.
Over the past few decades, however, the scientific community has revised its opinion. “We don’t have a good understanding of why these plants are emitting these cues,” Rick Karban, an entomologist who studies plant communication at the University of California, Davis, tells The Scientist. “We don’t even know if the cues that plants are emitting—that other plants can perceive and respond to—are somewhat intentional,” or just a byproduct of leaf damage.
A series of papers have shown that when a plant is damaged, it releases volatile organic compounds (VOCs) that prompt neighboring plants to mount their own chemical defenses against an impending herbivore attack. Karban says researchers are now focused on why the emitting plant puts out this signal, and whether it derives a benefit from telling those around it that it’s being eaten. It’s possible that surrounding plants are merely eavesdropping on the signal emitter, which derives no benefit from the situation.
“Understanding the intricacies of the plant world and plant-plant communication in more detail can potentially help us in plant protection in the agricultural context, if we can learn how to use these volatiles to turn on defenses in crop plants effectively,” [says Aino Kalske, a postdoctoral researcher in ecology and evolution biology at the University of Turku in Finland].