New mushroom species discovered in London grocery store

Scientists have discovered three new species in an unexpected place — a package of mushrooms purchased at a grocery store in London. CBC's Torah Kachur reports.

DNA barcoding tests 15 pieces in a package of porcini mushrooms

Samples of the new mushroom species are shown in the original packet, purchased at a grocery store in southwest greater London. (Bryn Dentinger/Royal Botanical Gardens, Kew)

What's a good place to look for undiscovered species? Remote rainforests? The deep ocean? What about your local grocery store?

That's where Bryn Dentinger and Laura Martinez-Suz, mycologists at the Royal Botanic Gardens, Kew, in London, recently discovered three new kinds of mushroom.

They were found in a package of dried porcini mushrooms from a grocery store in "southwest greater London" that the scientists tested using a technique called DNA barcoding. Dentinger had previously used the technique while researching mushrooms at the Royal Ontario Museum and the University of Toronto.

A typical porcini (Boletus edulis var. clavipes) is shown in its natural habitat in Algonquin Provincial Park in Ontario. (Brent Dentinger/Royal Botanical Gardens, Kew)

The technique involves matching the DNA profile of a sample to a database of known species in order to identify the sample. But in three out of 15 pieces tested from the porcini mushroom package, no match was found.

"None of them had scientific names, so these were essentially new species to science," Dentiger told CBC science columnist Torah Kachur. "And we found three different species in the 15 pieces that we sampled from."

CBC science columnist Torah Kachur

The team published their results in the journal PeerJ.

As it turns out, "porcini" is "a gastronomical label more than it is scientific," Kachur told CBC's The Homestretch. "What the Italians originally called porcinis were this unique flavour of nutty type of mushroom."

On the other hand, porcini mushrooms do tend to belong to a family of mushrooms known by scientists as boletes, which have tubes on their undersides instead of gills.

"Even though we don't necessarily know those species, all of them are certainly safe for consumption," Kachur said.

She said the new findings suggest that mushrooms are more diverse than scientists thought. It also highlights one of the mysteries of mushroom evolution.

"What is the evolutionary history that means they look the same and yet they are very genetically different?" Kachur mused. "We don't have the answer for that."