14 DAY TRIAL // When you think about communication plants don't usually come to mind - they are supposed to be rather passive beings. However, scientists have gathered in the last years more and more evidences that they actually communicate and have an active system of responding to threats from insects or other pests.
Plants signal each other via the release of certain odors and prop up their defense system when they detect such odors. For example when sage brush is damaged by insects, it releases a certain chemical called methyl jasmonate and other plants pick up on these smells and begin increasing the level of an enzyme called PPO. This enzyme protects the leaves from the attack of various parasites - they are around 60 percent less likely to be damaged.
What is interesting is that not only other sage brush detect and interpret these signals but even plants such as the tobacco plant are capable of doing it. This is surprising because the tobacco plant is rarely found alongside the sage brush plant. The new research conducted by Andre Kessler, an assistant professor of ecology and evolutionary biology at Cornell University, has shown that the tobacco plant props up its defense only when it gets such signals. Otherwise it uses the same proteins and nitrogen and carbon based chemicals to produce seeds.
"By priming its defense response the plant is not investing resources before it is actually attacked," said Kessler. "This could be a crucial mechanism of plant-plant communication."
It was also found that the plants are actually able to detect whether the damages are caused by insects or are accidents. When scientists crushed some leaves and branches the injured plants still released various airborne chemicals but the other plants didn't respond to them.
An even more interesting discovery was made by researchers from the Max Planck Institute for Chemical Ecology in Jena. They have discovered a species of wild tobacco plant growing in the southwestern United States that when under attack by hornworms, it releases chemicals attracting insects that kill the larva.
Thus, plants are engaged in various types of chemical communication not only among themselves or with other plant species, but also with some insects. Such plant-insect communication helps both the plant (which gets protected from pests) and the insect (which uses the chemical signals to find their prey easier).