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Genes matter for truffle aroma: geography not as important to a prized fungus' scent.

Mon dieu! A truffle's delectable aroma may be as much about genetics as it is about geography.

For years a truffle's flavor has been attributed mostly to environmental factors, akin to how terroir--the soil, climate and geology of a region--bestows qualities to wine. But a new analysis, published in the May New Philologist, finds that a truffle's particular blend of chemical compounds is linked instead to its genetic background.

By casting light on what gives these elusive underground fungi their prized flavor, the study could help transform some truffles from species harvested in the wild to consistent crops.

"Truffles are a really valuable natural resource, and it's the aroma that really gives them their value," says Gregory Bonito of Duke University, an expert in truffle evolution.

But teasing out what gives a truffle its aromatic oomph has been tough, thanks in part to the complexity of the truffle lifestyle. Truffles are the fruiting body of a particular group of fungi. These fungi strike up partnerships with various tree species, so that the fungal spores germinate and grow into threadlike structures on the trees' roots. When fungal threads of different mating types find one another in the soil, sexual reproduction occurs and small truffles develop, 10 to 30 centimeters deep. The most prized species of the gastronomic delicacies may sell for thousands of dollars a pound.

Some enthusiasts attribute a truffle's aroma to its patch of soil, or whether spring was wet enough or winter cold enough. Another factor may be the tree species colonized. And truffles themselves are colonized by microbes thought to contribute to the warty lumps' flavor.

Although the genetic blueprint for the famed black Perigord truffle (Tuber melanosporum) was published in 2010, the genetic particulars of other truffles aren't well understood. "We wanted to add the genetic dimension into the picture," says Richard Splivallo of the University of Gottingen in Germany, who led the new work.

So the researchers collected more than 200 Burgundy truffles from seven countries over four years. The scientists examined the profile of some of the 20 to 50 volatile chemicals that contribute to the truffle's delicate, nutty flavor.

When the researchers grouped the truffles by their genetic relatedness, truffles that were more closely related had more similar volatile profiles than more distantly related truffles.

"This is the first study to show a clear link between volatiles and genetics," says Claude Murat, who studies truffle genetics at the French National Institute for Agricultural Research in Nancy.

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Title Annotation:Molecules
Author:Ehrenberg, Rachel
Publication:Science News
Article Type:Brief article
Geographic Code:1USA
Date:May 5, 2012
Words:424
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