Research by Japanese scientists has shown that temperature and rainfall are key factors influencing and driving communication among fungi.
A forest typically resonates with sounds from various “residents,” such as birds, insects, and frogs. Particularly after rainfall, these sounds become even more pronounced.
Laccaria bicolor is the species of mushroom used in the experiment in Japan. (Photo: Flickr).
However, not all conversations in the forest are audible, and not all sounds originate from animals.
In a recent study published in Fungal Ecology, Japanese scientists discovered that rainfall can cause certain types of mushrooms to communicate with each other using secret signals, according to ScienceAlert.
Rainfall and Temperature Affect Fungal Activity
The researchers focused on a small, tan mushroom known as Laccaria bicolor, which grows on the forest floor of a secondary mixed forest at the Kawatabi Field Science Center of Tohoku University (Japan).
Mushrooms with electrodes attached to monitor signaling activity. (Photo: Yu Fukasawa).
In this study, the Japanese researchers attached electrodes to a cluster of six Laccaria bicolor mushrooms growing along a trail in the forest. These mushrooms were positioned near a Quercus serrata tree and a Carpinus laxiflora tree, both of which are potential symbiotic partners for Laccaria bicolor.
The research team monitored the voltage of the mushrooms, measuring in megavolts over a period of two days at the end of September and the beginning of October 2021. The initial study site was quite sunny and dry, with little rainfall recorded in the 12 days prior.
On October 1, when Typhoon Mindulle hit, the area received 32 mm of rainfall. About 1-2 hours after the rain, the mushrooms began to show signs of new activity.
Microbial ecologist Yu Fukasawa from Tohoku University noted that initially, the mushrooms emitted few signals due to the lack of rainfall. However, after the rain, the signals began to fluctuate and sometimes exceeded 100 megavolts.
According to Fukasawa and colleagues, this fluctuation correlates with changes in rainfall and temperature. Through signal analysis, the research team found that after the rain, the mushrooms began to transmit signals to each other. The transmission of signals was stronger among mushrooms located close to one another.
The findings of this study are still new and many aspects remain unclear, but they add a piece to the puzzle regarding the role of fungi in ecosystems hidden beneath forest canopies.
Previous Studies Indicate Fungi Can Communicate
Laccaria bicolor is an ectomycorrhizal fungus that forms symbiotic relationships with several plant species, including many large trees like oaks and pines. They enhance water and nutrient supply to these trees in exchange for carbohydrates.
Previous research has also indicated that Laccaria bicolor indirectly aids some carnivorous plants by attracting insects, killing them with toxins, and subsequently sharing the nitrogen from these animals with the host plants.
While some types of mycorrhizal fungi penetrate the cell walls of host plants, ectomycorrhizal fungi like Laccaria bicolor build “sheaths” underground, surrounding the outer parts of tree roots.
These “sheaths” are composed of fungal filaments. These filaments function like roots to promote fungal growth. When the filaments are interconnected underground, they form linking systems known as mycorrhizal networks.
Such underground networks function as a type of “wood-wide web,” where the entire forest communicates information through signals transmitted down to the roots and the mycorrhizal fungi.
While mycorrhizal networks do exist, there is currently insufficient evidence to demonstrate whether they reach the same scale and complexity as the wood-wide web.
Previous studies have indicated that fungi generate voltage variations in response to changes in their environment. Some hints suggest that these voltage signals may serve as a form of communication.
For instance, a study published in Royal Society Open Science in 2022 found that scientists discovered nerve-like electrical activity patterns in certain fungi. This activity can be likened to human language structures.
Accordingly, the research team identified around 50 different “words” in the electrical activity generated by the fungal networks.
Another study published in Communicative & Integrative Biology in 2020 also found that plants can send secret signals underground, potentially without the need for mycorrhizal fungi.
