Plants Use Underground Fungal Networks To Warn Of Aphid Attacks, Study Says

Plants can communicate through an underground network of fungus to sound alarm of an attack from aphids, according to a new study.

The roots of most land plants are colonized by a fungus called mycorrhizal that provides the plants mineral nutrients in exchange for carbon. The researchers have shown that mycorrhizal mycelia can also act as a conduit for signaling between plants, acting as an early warning system for herbivore attack. 

It's a "you scratch my back, I scratch yours" sort of system.

"Mycorrhizal fungi need to get [products of photosynthesis] from the plant, and they have to do something for the plant," said John Pickett of Rothamsted Research, in an interview with the BBC.

While instances of plant communication through the air have been recorded, this study is reportedly the first to demonstrate that the underground fungal networks also aid in communication.

For the experiment, researchers from the United Kingdom institutions University of Aberdeen, the James Hutton Institute and Rothamsted Research grew five sets of broad bean plants.

They allowed the fungal network to develop on some of the plants to develop mycorrhizal networks, and preventing the networks' growth in the others. They covered the plants with bags to ensure that any through-the-air communication would not affect the experiment.

Researchers then allowed one plant in each test group to be infested with aphids. They found that if the infested plant was connected to other via a fungal network, the un-infested plant would begin to mount its chemical anti-aphid defense. The plants not connected by fungal networks appeared not to receive signal of an attack and showed no chemical response.

The find could be of use to farmers, who might be able to arrange a sort of "sacrificial" plant that would be more prone to aphid infestation so that the infected plant can alert other plants in the crop.

The study was published recently in the journal Ecology Letters.