Plants ‘Talk’ via Funghi To Warn About Impending Dangers
A study has found that plants talk to one another when under attack via the symbiotic funghi mycorrhizae.
Networks of mycorrhizae cover the roots of most plants, using their larger underground surface area to gather up more water and nutrients that the plant roots could possibly gather alone. They also improve surrounding soil quality, sending out root threads to separate clay platelets and get air and water to the main roots. Now, a team of biologists has proven that the funghi is even more vital to species survival than previously thought.
“Here, we show that mycorrhizal mycelia can also act as a conduit for signalling between plants, acting as an early warning system for herbivore attack,” write the authors in a study published in Ecology Letters.
When under attack by aphids, certain plants release chemicals that trigger a scent that repels aphids and attracts predators that will help rid the plant of aphids. These chemicals, known as volatiles, also travel through the air and tell neighbouring plants to start releasing their own volatiles.
A joint team from the University of Aberdeen, the James Hutton Institute and Rothamsted Research set out to discover what would happen if plants under attack could not communicate via the air, but were only linked up by the funghi.
Bean plants, which release an aphid-repelling and wasp-attracting chemical, were grown in groups of five, with three connected by the funghi and two without the funghal links. Each plant was covered with a bag, so that no communication could occur via the air. When one plant was purposefully infested with aphids, those joined to it began releasing the same chemical. Those unconnected, failed to release the chemical.
“Connected plants that weren’t infested by the aphids behaved as though they were,” David Johnson of the University of Aberdeen said in a statement. “We don’t quite know the mechanism of communication, but it’s likely to be a chemical signal.”
The find is a key step in finding natural ways to protect crops from predators. Rothamsted Research is already looking to engineer a type of wheat that releases the (E)-β-farnesene odour released by 400 plants in nature, an odour that repels aphids and attracts aphid-attackers, in this instance ladybirds. The idea is to use nature as inspiration for genetically modifying crops, so that damaging fertilisers become defunct. Better still, if natural funghal networks that already exist in crops — such as rice, barley and wheat — can be employed in the aphid-battle.
“Aphids affect all higher-latitude agricultural regions, including the UK, the EU, North America, and North East Asiam” said coauthor John Pickett of Rothamsted Research. “This research could provide a new, sustainable and natural intervention. In a field of plants that have some inducible resistance to aphids, we could use a plant that’s susceptible to aphid attack to ‘switch on’ the defence mechanism through the natural underground connection. There’s the potential to deal with other pests and diseases, in other regions, in a similar way.”
Essentially, one plant would be sacrificed for the sake of all others.
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