How often have you heard the phrase ‘I heard it through the grapevine’? New research has potential to give new meaning to the famous lyric, and the findings point to the importance of being well-connected.
Plant scientists at the University of Aberdeen, The James Hutton Institute, and Rothamsted Research have shown that plants use underground fungal networks to warn each other of impending aphid attack. Similar to a particularly hilarious cat photo doing the rounds on Facebook, or Twitter erupting over Ryan Gosling, plants communicate the threat of impending aphid attack to their neighbours through networks of fungal mycelia. Mycelia are thread-like, branching networks that form the vegetative parts of fungi – unlike the fruiting bodies, which appear at the surface, mycelia operate underground, continuously harvesting nutrients. The new findings suggest that they may also act as a rudimentary sort of World Wide Web for plants.
To test the idea that plants connected by fungi warn each other of attack, the researchers grew bean plants (Vicia faba) in groups of five. Three of the plants were allowed to grow fungal mycelia between their roots, while the other two were prevented from growing the mycelia. One of the plants in each group was infested with aphids, causing the plant to release chemicals intended to repel aphids and attract wasps, one of the aphids’ natural predators. The plants were covered with bags to prevent chemical communication through the air.
Plants that were not infested with aphids, but were connected to the infested plant by the fungal network, also started to produce the defensive chemical response, while the plants that were isolated from the fungal network did not produce the defensive response. The plants connected through the fungal network received advanced warning of the aphid attach, and were able to defend themselves, while the isolated plants remained vulnerable. The plants were probably using the fungal network to communicate using chemical signals.
The arbuscular mycorrhizal fungi that grow the interconnecting networks of mycelia commonly live in symbiosis with a wide range of plants, including many agricultural crops. The researchers behind the study think that there might be great potential for turning the ability of plants to gossip using the fungal net to our advantage: by identifying the chemical compound used to signal to other plants, and using a plant vulnerable to aphid attack to trigger a defensive response in others, plant scientists could develop a natural and sustainable method to limit the damage done to crops by aphids.
The research is published in Ecology Letters: Underground signals carried through common mycelial networks warn neighbouring plants of aphid attack. This post draws upon the following James Hutton Institute news item: Plants use underground networks to communicate danger.