Mushrooms Communicate With Electrical Signals After Rain

Did you know that mushrooms might be having secret electrical conversations underground? According to a new study, scientists in Japan found that rain prompts certain fungi to communicate using underground electrical signals. Freaky, huh?

The researchers focused on small tan mushrooms known as bicoloured deceivers (Laccaria bicolor), which they found growing on the floor of a secondary mixed forest at the Kawatabi Field Science Center of Tohoku University in Japan. These fungi form symbiotic relationships with certain plants and help them get more water and nutrients in exchange for carbohydrates. Previous research suggests that L. bicolor might even help trees feed on animals by luring insect relatives called springtails and killing them with toxins, sharing the animal's nitrogen with their host trees. Talk about a killer relationship! These mushrooms build subterranean "sheaths" around the exterior of a tree's roots made of hyphae, the root-like filaments that fuel the growth of a fungus. When the hyphae of mycorrhizal fungi link underground, they form interconnected systems known as mycorrhizal networks that act like a kind of "wood-wide web," where entire forests communicate via chemical signals down tree roots and mycorrhizal fungi. Who knew fungi were so social?

This study adds to a growing body of research delving into these relationships, revealing fascinating details about how they work. Earlier studies have shown fungi producing variations in electrical potentials seemingly in response to changes in their environment, with clues suggesting these signals serve as a form of communication. Researchers attached electrodes to a cluster of six L. bicolor mushrooms they found growing on the side of a forest trail and monitored their electrical potential for about two days in late September and early October 2021. The mushrooms were located near a jolcham oak (Quercus serrata) and a loose-flower hornbeam (Carpinus laxiflora), both potential symbiotic tree species for L. bicolor. After Typhoon Mindulle brought 32 millimeters of rain, the mushrooms began showing new signs of activity. The fluctuation in electrical potential after rainfall showed evidence of signal transport among mushrooms, especially between mushrooms located closer to one another on the forest floor.

"Our results confirm the need for further studies on fungal electrical potentials under a true ecological context," says microbial ecologist Yu Fukasawa of Tohoku University. The study was published in Fungal Ecology. So next time you're walking through the forest, keep an ear out for the silent hum of the fungi having a conversation underground.