Liquid from root-like structures may make mushrooms grow

We don’t generally think of mushrooms as juicy, but their growth may be fueled by a mysterious liquid secreted from their root-like structures, a new study suggests (J. Agric. Food Chem. 2023, DOI: 10.1021/acs.jafc.3c03633). “Many people who are involved in [the] mushroom industry and mushroom science know the liquid,” says Hirokazu Kawagishi, a natural products chemist at Shizuoka University who led the work, in an email. “However, no researchers in mushroom science have paid attention to the liquid until now.”

Mushrooms growing from a wood stump or poking out from leaf litter might look like free-standing organisms, but actually they are fruiting bodies of various fungi—much like how trees and other plants produce apples or berries. Mushroom-producing fungi consist of a web of filaments called mycelium , which acts as a root system from which the mushrooms grow.

Kawagishi and his colleagues obtained liquids from lab-grown mycelium of two different fungi—Hypholoma lateritium (English common name: brick caps) and Hericium erinaceus (English common name: lion’s mane).

They extracted 4 novel compounds from the two liquids­—1 from H. lateritium and 3 from H. erinaceus—and using multiple analytical techniques, determined their composition and structure. Compounds 1, 3, and 4 induced the formation of mushrooms in a mushroom-producing fungus called Flammulina velutipes (English common name: velvet foot). The compounds also had other bioactive effects: Compounds 2 and 4 appear to inhibit a protein that regulates response to cellular stress. All four of the compounds tamped down the activity of a kinase thought to promote tumor growth.

Kawagishi believes there’s more to learn about this substance, which he and his colleagues called “fruiting liquid.” Although plant and animal hormones are well-studied, researchers know next to nothing about mushroom hormones, which Kawagashi believes regulate the mushroom life cycle. He intends to study mushrooms’ fruiting liquid further to try to find hormones there.