Trouble with truffles

Long-feared Chinese species infiltrates Italian soil

A Chinese truffle with a reputation as a takeover artist has turned up growing in the soil of an Italian truffle plantation.

THE REAL THING A Périgord truffle grown in Italy looks roughly like its possible underground competitor, the Chinese black truffle Tuber indicum, but commands a much higher price. Murat

TRADITION INVADED A sophisticated scent detector on four legs searches out Périgord truffles that form underground near Dr´me, France. That native truffle species may now face tough competition from a Chinese species just discovered growing in Italy. Murat

“We dreaded it, and it has happened!” Claude Murat of the University of Torino in Italy and his colleagues write in an upcoming paper in New Phytologist.

Samples of soil and tree roots in an unnamed plantation in the Italian Piedmont revealed DNA from the Chinese black truffle, Tuber indicum, Murat says. Soil samples also contained DNA from the desired Périgord truffle, or T. melanosporum, one of the European natives that out-prices its Chinese relative.

“We dread that T. indicum will spread all over Europe and crowd out T. melanosporum and perhaps other truffle species,” Murat explained by email.

As far as he knows, the two truffles have never gone fungus-to-fungus outdoors in European soil before, Murat says. Yet researchers have inoculated plants in the lab with both species, and the Périgord disappeared. The Chinese truffle took over.

“Most people who are working on truffles will be very concerned to read the paper by Murat,” says Ian R. Hall of the consulting firm Truffles & Mushrooms, in Dunedin, New Zealand. Hall laments that invasive plants and animals overshadow rogue fungi for public attention. “They’re creating havoc too but underground.”

The supposed aggression of the Chinese truffle comes from lab studies, cautions Jason Hoeksema, an ecologist at the University of Mississippi who studies fungi on plant roots. “We definitely do not have enough information to know what will happen,” he says.

The specter of truffle infiltration has loomed over Europe in recent years, but Murat says he and his colleagues discovered this first case by chance. More than 10 years ago a would-be truffle entrepreneur had planted young trees treated with spores, the modern way of starting a black truffle plantation. After such a long time without a truffle, the grower called in the geneticists to check the soil.

Murat says that the company that inoculated the plantation’s stock has gone out of business, and he can only speculate on whether workers got the similar-looking species mixed up or intentionally substituted the cheaper Chinese truffle to cut corners.

That would be a sizable corner, according to Ed Baker of the specialty food supplier Earthy Delights in DeWitt, Mich. In season, restaurant chefs pay him between $300 and $600 a pound for Périgord truffles but between $50 and a $100 a pound for the Chinese ones. Retail prices soar higher.

Hall has tasted Chinese truffles in their native land, where he is told that farmers fed the black truffle lumps to pigs before discovering some 10 years ago that Westerners would pay for the species. “It was OK but certainly didn’t have the huge aroma that melanosporum has,” Hall says. (Perhaps not so cutting a critique, considering that Hall describes another truffle, one of the less-favored European natives, as “tasting like your driveway.”)

Chefs training at the Culinary Institute of America in Hyde Park, N.Y., now get a truffle education that includes Chinese examples. “Most hard-core traditionalists scoff at them,” says institute professor Jonathan Zearfoss. “They are less flavorful but decent for what they are.”

The flavor and odor matter in the wild, too, says Jim Trappe of OregonStateUniversity in Corvallis. The lumps that people think of as truffles are just the underground reproductive structures that form spores. The rest of the fungus grows as a cobwebby network enswathing and poking into tree rootlets. Reproducing underground gets tricky when it comes to dispersing spores. Truffles manage by exuding such nose-swamping odors that squirrels, mice and other creatures can dig through the soil for the treat and end up as accidental spore carriers.

Europe may have the most human-enticing underground fungal reproductive structures, aka truffles. But Trappe points out that North America has some 1,000 native species of fungi that reproduce with subterranean lumps, and Australia has even more. Both continents now have Périgord truffle plantations of their own. In theory, they too could be colonized by Chinese black truffles.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.