Mushrooms Conduct Underground Communication After Rain

Forests are usu­al­ly full of sounds from the beings resid­ing in there, espe­cial­ly after rain. You can hear the chirp­ing of birds, buzzing of insects and croak­ing of frogs.

How­ev­er, not all con­ver­sa­tions in the for­est are audi­ble and not all ani­mals are involved. Japan­ese researchers have now found an inter­est­ing clue that rain caus­es some fun­gi to com­mu­ni­cate through under­ground elec­tri­cal signals.

The research team focused on small brown fun­gi known as Lac­caria bicol­or grow­ing in the soil of a mixed sec­ondary for­est at Tohoku Uni­ver­si­ty’s Kawatari Field Sci­ence Cen­ter. L. bicol­or is an ecto­my­c­or­rhizal fun­gus that forms sym­bi­ot­ic asso­ci­a­tions with cer­tain plants like oak and pine trees. It pro­vides water and nutri­ents in exchange for carbohydrates.

Ear­li­er stud­ies have shown that L. bicol­or attracts and kills spring­tails, insects, with tox­ins to share their nitro­gen with host trees and per­haps pre­vent some trees from eat­ing ani­mals indirectly.

While some myc­or­rhizal fun­gi pen­e­trate the cell walls of host plants, ecto­my­c­or­rhizal fun­gi like L. bicol­or form under­ground sheaths out­side the roots of trees. This sheath com­pris­es root-like threads known as hyphae that facil­i­tate the growth of the fun­gus. When the hyphae of myc­or­rhizal fun­gi com­bine under­ground, they form an inter­con­nect­ed sys­tem called the myc­or­rhizal net­work. It is pro­posed that this under­ground net­work acts like a “wood wide web” con­nect­ing trees across a for­est through chem­i­cal sig­nals trav­el­ing through tree roots and myc­or­rhizal fungi.

Though myc­or­rhizal fun­gal net­works exist, there is lit­tle evi­dence to sup­port whether they reach the scale and intri­ca­cy of what is called the wood wide web. Some sci­en­tists say many pop­u­lar expla­na­tions for the phe­nom­e­non are exag­ger­at­ed. How­ev­er, recent stud­ies like this are delv­ing into the details of such rela­tion­ships and reveal­ing fas­ci­nat­ing insights into their functioning.

Ear­li­er research has shown that fun­gi gen­er­ate changes in elec­tri­cal poten­tial in response to envi­ron­men­tal changes, pro­vid­ing hints that these sig­nals may func­tion as a form of com­mu­ni­ca­tion. For instance, a 2022 study found nerve-like pat­terns of elec­tri­cal activ­i­ty in some fun­gi com­pa­ra­ble to the struc­ture of human speech. The study iden­ti­fied up to 50 “lan­guages” of groups of elec­tri­cal activ­i­ty spikes emit­ted by the fungi.