British researchers released a study on Thursday saying that plants can communicate with each other by using an underground network of fungi. According to the BBC, the study, published in the journal Ecology Letters, said that plants signal each other when they are under attack by aphids to that other plants can secrete chemicals that repel aphids and attract the wasps that are the aphids' natural predators.
Scientists from the University of Aberdeen in Scotland, the James Hutton Institute and Rothamstead Research joined forces to devise an experiment to test what role these threadlike fungi, called mycorrhizae, play in aiding communication between plants in distress.
The type of distress they chose to inflict on the plants and test their response was an attack by aphids. Aphids are tiny insects that feed on a variety of plants and many plants have developed an arsenal of chemical defenses to use against them.
The research team grew sets of five broad bean plants. In each set of five, three were allowed to grow mycorrhizal tissue around their roots. Two were prevented from doing so.
The scientists then isolated the plants from each other above ground, covering them with bags and thereby preventing airborne chemicals (one form of plant communication) from traveling from one plant to the other. Then, the team introduced the aphids.
In the plants that were connected by fungi, when a single plant was infected with aphids, the other two plants began to mount their chemical defenses, secreting aphid-repelling substances that also attract the wasps that feed on aphid larvae. The plants that were not connected by mycorrhizae were apparently not warned of the attack on the single plant in their group because they secreted no defensive chemicals.
When the bean plants come under attack, their chemical defenses trigger a reaction in the chemical composition of the fungi, causing a chain reaction that leads to the next bean plant, which, in its turn, detects the distress chemicals in the fungi and reacts by releasing its own chemical defenses.
John Pickett of Rothamsted Research told the BBC that the fungi are engaged in a two-way relationship with the bean plants.
"Mycorrhizal fungi need to get [products of photosynthesis] from the plant, and they have to do something for the plant," he said. "In the past, we thought of them making nutrients available from the [roots and soil], but now we see another evolutionary role for them in which they pay the plant back by transmitting the signal efficiently."
The discovery took scientists by surprise, but Pickett calls the fungal network "a fantastic signaling system."
The team hopes that their discovery can contribute to pest-resistance and additional hardiness for food plants in the field.
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