Plants communicate via scents, can we decipher their messages?

Subject: Deciphering the mysterious communications between plants - Comments and suggestions are welcome! Don't hesitate and leave a comment on our comment section down below the article!

By Universal-Sci

A dense forest. There might be more going on here than meets the eye - Image Credit:  Jakub Gorajek via Unsplash  -  HDR tune by Universal-Sci

A dense forest. There might be more going on here than meets the eye - Image Credit: Jakub Gorajek via Unsplash - HDR tune by Universal-Sci

It has been known for some time now that plants are able to communicate among themselves. Plants are able to, for example, eavesdrop on the chemical signals of their peers. If they detect a potential damaging insect nearby, they can proactively ramp up their defenses. In addition they can defend their territory from other plants by creating a defensive barrier. It has even been discovered that they poses the ability to communicate with different types of organisms like mammals.

An example of the latter can be found in a study published in Current Biology. The study showed that a specific species of plant was able to interfere with bat communication in order to help them find its location. Bats provide fertilizer for this specific species and so it is to the plants benefit to attract them.

Some plants try to kill of the competition by generating damaging chemicals. Other plants on their turn have been found to create a protective barrier against those chemicals by releasing oxalic acid.

Another interesting example: when plants are being eaten by caterpillars they produce dozens to even hundreds of different scents. Natural enemies of caterpillars, such as parasitic wasps, are able to smell some of these substances and consequently feel attracted to the affected plant.

Neighboring plants might also ‘smell’ these scents and follow up on this by putting their defenses on standby. From the many volatile substances secreted by plants, only a small number of scents appear to be attractive for parasitic wasps. It is often unknown which substances exactly pass on what message.

- Image Credit:  Tobial Tullius via Unsplash

So, although some research has been done, the vast majority of inter-plant communication still eludes us. Researchers from Wageningen University tried to decipher some of the mystery.

Every fragrance appears to have its own reliability

In the Wageningen study, a model has been developed that simulates the effects of the scent as soon as they end up in the air. It turns out that some scents provide reliable signals, indicating that a plant is being damaged by eating insects, while other scents turn out to be unreliable predictors.

Whether a scent is reliable or not is partly determined by its chemical properties. Some scents are degraded so quickly under the influence of ozone and other substances that their concentrations remain very low, making them very difficult to detect. On the other end of the spectrum there are scents that remain intact for so long that they do not provide reliable information about the location of their source.

It also appears that some scents are still being produced and remain in the air after caterpillars have stopped eating. As a result parasitic wasps may wrongly assume that the caterpillars are still there

The modeled calculations brought forth by the researchers appear to be reliably in sync with what field observations and lab tests encountered. The model has been applied to poplar trees (A type of tree that is indigenous to the Netherlands and other parts of northwestern Europe) but can also be used for other species if the correct data is available.

With this study the first step has been made into deciphering the language of plants. It will be a vast undertaking though, as plants are able to produce many (sometimes even hundreds) different types of scents.

If you’re interested and in the need for more details about the Wageningen study you can read it here: "What makes a volatile organic compound a reliable indicator of insect herbivory?"

Sources and further reading:

Wageningen University & Research press release

Publication: "What makes a volatile organic compound a reliable indicator of insect herbivory?"

5 ways plants communicate

Volatile communication between plants that affects herbivory: a meta‐analysis

Plants creating a defensive barrier using oxalic acid

Bats Are Acoustically Attracted to Mutualistic Carnivorous Plants

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