Yuya Fukano

Vines are antisocial climbers. They send out tendrils to taste nearby plants, identifying and then steering clear of similarly weak-stemmed varieties.

Climbing plants are known to have a highly attuned sense of touch, which helps them scale other plants and structures. As soon as their tendrils brush up against a potential scaffold, they coil tightly around it.


Yuya Fukano at the University of Tokyo has now shown that some vines can also sense chemicals. If they don’t like the “taste” of the plant to which they are tethered, they will uncoil themselves and retreat.

Fukano found that tendrils of the Cayratia japonica vine only stayed wrapped around other plants if they were non-vine species like shrubs. When presented with other C. japonica specimens, they held on for less than 2 hours.

Vines probably avoid climbing up other vines because they are flimsier than other plants, says Fukano. Moreover, it is easier to compete with a non-climbing plant for light and space.

As for how vines can tell what plants they are in contact with, Fukano showed that C. japonica tendrils can taste a chemical called oxalate. C. japonica itself contains high levels of oxalate, so detecting the chemical tells the tendril whether it is touching a member of its own – or a different – species.

When presented with a variety of plants, the vine avoided those with high oxalate contents the most. It also avoided plastic sticks coated with oxalate, but not other chemicals, like agarose and citric acid.

This is the first report of a plant being able to sense chemical cues via direct contact, Fukano says. Some parasitic plants can “smell” chemicals emitted by other plants, but oxalate is non-volatile and so can only be detected upon contact.

Fukano and his colleagues have now shown that several species of vines are also capable of chemical sensing during contact, suggesting the ability may be widespread among this group of plants.

The next step will be to determine exactly how plants detect chemicals. One possibility is that vine tendrils contain oxalate receptors, says Fukano.

It’s a feasible theory, says Mike Haydon at the University of Melbourne, Australia, but he feels it’s not conclusive that oxalate is the compound that’s being sensed. “It could be some other chemical signal,” he says. “We have a lot to learn about plant receptors that sense signals from the environment.”

“To be frank,” says Fukano, “we are still groping around in the dark.”

Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2016.2650