After heavy rains, strange things appear in California's forests and shrubs. Fungi that live quietly in the soil come to life with the moisture and sprout fruiting bodies. Some take on the familiar mushroom shape with a stem and cap, while others resemble fluorescent coral, transparent blobs of brown jelly, or bright yellow buttons — bizarre shapes that are visible to the naked eye only for a brief moment when the microorganisms release their spores.
Every time a mushroom appears, it's an opportunity for mushroom hunters to identify a new species. According to a 2023 report from the Royal Botanic Gardens, Kew, as many as 95% of the fungi on Earth are still uncharacterized. For several years, professional mycologists and hobbyists alike have been sequencing the DNA of fungi they collect, says mycologist Mandy Quirk, communications lead for the California Fungal Diversity Survey, which aims to add tens of thousands of fungal sequences to scientific databases. Fungi enthusiasts often use sequencing to identify fungi that are appearing in a database for the first time as a species.
“If you go outside right now here in California, or anywhere in North America, you could easily find new species of mushrooms and fungi that have never been described before,” Quirk said.
At the Sonoma County Mycological Society's annual foraging camp in January, Quirk and his partner, Alan Rockefeller, helped hundreds of campers identify fungi they'd collected from forest soil near Occidental, California. Picnic tables were stacked with red-and-white paper takeout boxes, each containing a single fungus rather than corn dogs or fries. In a makeshift lab, volunteers demonstrated how to extract DNA from the fungi, which can be distinguished by sequencing short stretches of each fungus' genetic code.
When collectors receive a match to their sequence, they can enter the information into iNaturalist, a website where hobbyists can share their observations of the natural world. Meanwhile, organizations like the Ohio Mushroom DNA Lab and Mycota Lab, founded by University of Michigan biochemist Steven Russell, enter sequences into scientific databases that are accessible to the research community. In this way, the information generated by a distributed network of collectors can be fed directly to scientists and conservation organizations.
Quirk said there has been an explosion in gene sequencing in recent years: More than 21,000 samples have been sequenced already this year, up from 5,600 in 2022. “We'll probably be over 40,000 by the end of the year,” Quirk said.
And there are still many fungi that have yet to be identified. Some of these organisms, which live as hidden filamentous networks in the soil, may not produce fruiting bodies for years. But after heavy rains in Southern California, collectors might come across mushrooms that haven't been seen in decades, Quirk said.
The next step could then be to generate sequences from fungi in the soil, which will allow us to understand the true fungal diversity of North America and consider how to protect what's below the surface as the climate changes.
“We're at this incredible crossroads right now, and we have to solve this problem,” Quirk said.
