The truffle was grown as part of a program in Monmouthshire, South Wales, led by MSL in collaboration with local agricultural producers. The results of the program, reported in the magazine Climate Research, suggest that the cultivation of truffles may be possible in many parts of the United Kingdom.
After nine years of waiting, the truffle was harvested in March 2017 by a trained dog named Bella. The aromatic fungus grew within the root system of a Mediterranean oak that had been treated to stimulate truffle production. Additional microscopic and genetic analyses confirmed that Bella's finding was in fact a black Périgord truffle (Tuber melanosporum).
Black truffle is one of the most expensive delicacies in the world, worth as much as 1,900 Euro per kilo. They are highly appreciated because of their intense flavour and aroma, but their cultivation and harvest are difficult and slow, and they are usually limited to regions with a Mediterranean climate. Also, its Mediterranean habitat has been affected by drought due to long-term climate change, and yields are falling, while global demand continues to rise. The truffle industry is expected to generate about 5,000 million Euro annually in the next 10 to 20 years.
Black truffles grow underground in a symbiotic relationship with the root system of trees in soils with high limestone content. They are found mainly in northern Spain, southern France and northern Italy, where they are detected by trained dogs or pigs. Although they can appear naturally, many truffles are grown by inoculating oak or hazelnut seedlings with spores and planting them in calcareous soils. Nevertheless, even when resorting cultivation, there is no guarantee that truffles will grow.
"It is a risky investment for producers. Even though humans have been eating truffles for centuries, we know very little about how they grow and how they interact with their guest trees," said the co-author of the article, Professor Ulf Büntgen of the Department of Geography of Cambridge. "Given that they grow underground, we cannot see how truffles are affected by different environmental conditions, or even when it is the best time to water them," he adds.
In partnership with local farmers, Dr Paul Thomas, of MSL and the University of Stirling and Büntgen's co-author,, has been growing truffles in the United Kingdom for the past decade. In 2015, MSL successfully cultivated a native Burgundy truffle from the United Kingdom, but this is the first time that the more valuable black truffle from Périgord has been cultivated in such a northern and maritime climate. Its host tree is a Mediterranean oak that was planted in 2008. Before sowing, the tree was inoculated with truffle spores and the surrounding soil was less acidified, as it was lime-treated.
"This is one of the best truffle species in the world and the potential for the industry is huge," said Thomas. "We planted the trees just to monitor their survival, but we never thought that this Mediterranean species could actually grow in the United Kingdom. It's an incredibly exciting development."
Researchers have attributed the fact that black truffles can grow so far from their native Mediterranean habitat to climate change. "Different species respond to climate change at different scales and at different speeds, and there is often an ecological imbalance," says Büntgen, who illustrates this with insects, which can move quickly, while the vegetation they depend on may not be able to. "It is possible that truffles are one of these fast-changing species," he suggests.
"This has shown that the climate tolerance of truffles is much greater than previously thought, although it is likely that climate change is an essential factor," says Thomas. He also believes that truffles, and their host trees, are not just "a very valuable crop, but also a beneficial element for the preservation of the biodiversity."
The first harvested truffle, which weighed 16 grams, has been preserved for posterity, but in the future, the truffles will be distributed in restaurants in the United Kingdom.