̽��ֱ�� of Cambridge - truffle

Illuminating the hidden kingdom of the truffle

lw355 — Mon, 12 Feb 2018 11:00:12 +0000

“A unique aroma, a combination of newly plowed soil, fall rain, burrowing earthworms and the pungent memory of lost youth and old love affairs,” wrote the late American food writer Josh Ozersky about truffles.

His sensual words echo the almost hedonistic regard with which truffles are held, and go some way to explaining a price tag of around £1,700 per kilo for rarer species like the Périgord black truffle, and predictions that global sales of truffles will reach several billion GBP annually in the next decades.

Yet very little is known about the biology and ecology of these unassuming-looking fungi that grow naturally in connection with the fine root systems of trees.

Now, with the help of a well-experienced ‘truffle dog’ called Lucy and the Cambridge ̽��ֱ�� Botanic Garden, researchers from Cambridge’s Department of Geography have begun a ‘natural’ experiment to study the seasonal changes and productivity of the Burgundy truffle.

More common than the Périgord black truffle and the rarer-still white Alba truffle, Burgundy truffles are found across Europe and the eastern part of England, including in the 40-acre Botanic Garden planted by Charles Darwin’s mentor Professor John Stevens Henslow in 1846.

“We really don’t know much about the life of a truffle,” explains Professor Ulf Büntgen who, with PhD student Elisabeth Johnson, hopes to discover how, when and where truffles grow and mature, how their spores are dispersed and by which animals, and how their lifecycle is affected by changing environmental conditions, including climate.

“Truffles are remarkable organisms and interesting ambassadors for our fascinating but fragile soil ecosystems, which are considered one of the last big frontiers in science,” says Johnson. “Being able to delve into the mysteries of one of their enigmatic inhabitants is thrilling, especially since they are directly linked to above-ground biodiversity through their partnership with trees – it’s a meeting of two worlds.”

“ ̽��ֱ��beauty of using the Garden for this kind of research is that we have over 8,000 plant species and we’ve been here for 170 years. ̽��ֱ��trees have had lots of time to establish connections with truffles,” adds Professor Beverley Glover, Director of the Garden.

Truffles live in symbiotic partnership with a host tree – the plant delivers sugars and the fungi provide nutrients. However, as soon as the truffle is unearthed, the truffle’s ecosystem, including its mutualistic partnership, is destroyed.

“No-one has succeeded in creating the necessary complexity of real-world conditions in a normal lab to understand the below-ground lifecycle of the truffle,” explains Büntgen. “ ̽��ֱ��Cambridge ̽��ֱ�� Botanic Garden is an almost perfect living laboratory, potentially allowing us a glimpse into the life cycle and community structures of truffles across time and space. It is an immense privilege to be able to carry out this kind of research at this historic site.”

̽��ֱ��Garden was founded to support the ̽��ֱ��’s teaching and research, which it still does today. “What’s exciting about this project for the Garden team are the many ‘firsts’,” says Glover. “It’s the first time we’ve looked at the truffles below our trees, the first time we’ve had a dog involved in research, and as far as we know it’s the first time in the world that anyone has looked at which species of tree these truffles can grow on.”

One area of interest to the researchers is the possibility of climate-induced range shifts in the habitats of truffles. Büntgen’s previous research looked at why yields of the Périgord truffle in Spain, France and Italy have been in decline since the mid-1970s. His work using tree rings as a read-out for the effect of climate on growth showed that falling Mediterranean truffle harvests coincided both with drier summers and reduced growth of Spanish oaks.

In another recent study, Büntgen described the first cultivation of Périgord black truffles in the UK, suggesting that black truffles are able to grow far outside their native habitat.

“Ecological range shifts can have implications for rural tourism, regional agriculture and global prices,” he adds. “We hope that new understanding of the hidden life of the Burgundy truffle will help us to understand the environmental drivers of the growth and maturation of other members of this remarkable family.”

̽��ֱ��results from the long-term Botanic Garden experiment will be combined with a larger study of around 30 sites in Switzerland, Germany and Spain.

Lucy will be vital to the success of the project. Büntgen trained his family pet in just four days. Given the chance, she would happily search the undergrowth for many hours simply for the pleasure of finding, digging up and wolfing down one of these nutty-smelling delicacies.

“You never train a dog to smell a truffle – they smell everything. You just train the connection. Lucy is a hunting dog that likes food – she’d harvest for six hours in a row if we let her. Without a dog like Lucy you simply don’t know where to dig.”

Once Lucy has found a truffle, the researchers move in quickly, before she has the chance to snaffle the luxury. As she happily eats her own reward, Büntgen and Johnson take measurements, recording aspects of the truffle and its environment, including its host tree, before removing it for further analysis.

Meanwhile Johnson has decided not to eat truffles for the duration of her PhD: “I find them far too fascinating to eat. Discovering truffles as living beings in our complex ecosystems as a whole gives me immense delight. When not removing them in the name of science, we try to leave their habitat relatively undisturbed to understand how they interact with wildlife and how they unfold new living networks within the deeply fascinating and little-understood world below our feet.”

All truffles unearthed at the Botanic Garden are for research purposes.

Truffles are one of the world’s most expensive ingredients, and also one of the most mysterious. Now, with the help of a 170-year-old ‘living laboratory’, and a dog called Lucy, researchers hope to unearth new understanding of the secret life of these underground delicacies.

Truffles are remarkable organisms and interesting ambassadors for our fascinating but fragile soil ecosystems

Elizabeth Johnson

Illuminating the hidden kingdom of the truffle

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Périgord black truffle cultivated in the UK for the first time

sc604 — Mon, 06 Nov 2017 00:01:02 +0000

Researchers from the ̽��ֱ�� of Cambridge and Mycorrhizal Systems Ltd (MSL) have confirmed that a black truffle has been successfully cultivated in the UK for the first time: the farthest north that the species has ever been found. It was grown as part of a programme in Monmouthshire, South Wales, run by MSL in collaboration with local farmers. ̽��ֱ��results of the programme, reported in the journal Climate Research, suggest that truffle cultivation may be possible in many parts of the UK.

After nine years of waiting, the truffle was harvested in March 2017 by a trained dog named Bella. ̽��ֱ��aromatic fungus was growing within the root system of a Mediterranean oak tree that had been treated to encourage truffle production. Further microscopic and genetic analysis confirmed that Bella’s find was indeed a Périgord black truffle (Tuber melanosporum).

̽��ֱ��black truffle is one of the most expensive delicacies in the world, worth as much as £1,700 per kilogram. Black truffles are prized for their intense flavour and aroma, but they are difficult and time-consuming to grow and harvest, and are normally confined to regions with a Mediterranean climate. In addition, their Mediterranean habitat has been affected by drought due to long-term climate change, and yields are falling while the global demand continues to rise. ̽��ֱ��truffle industry is projected to be worth £4.5 billion annually in the next 10-20 years.

Black truffles grow below ground in a symbiotic relationship with the root system of trees in soils with high limestone content. They are found mostly in northern Spain, southern France and northern Italy, where they are sniffed out by trained dogs or pigs. While they can form naturally, many truffles are cultivated by inoculating oak or hazelnut seedlings with spores and planting them in chalky soils. Even through cultivation, there is no guarantee that truffles will grow.

“It’s a risky investment for farmers – even though humans have been eating truffles for centuries, we know remarkably little about how they grow and how they interact with their host trees,” said paper co-author Professor Ulf Büntgen of Cambridge’s Department of Geography. “Since the system is underground, we can’t see how truffles are affected by different environmental conditions, or even when the best time to water them is. There’s been no science behind it until now, so progress is slow.”

In partnership with local farmers, Büntgen’s co-author Dr Paul Thomas from MSL and the ̽��ֱ�� of Stirling has been cultivating truffles in the UK for the past decade. In 2015, MSL successfully cultivated a UK native Burgundy truffle, but this is the first time the more valuable black Périgord truffle has been cultivated in such a northern and maritime climate. Its host tree is a Mediterranean oak that was planted in 2008. Before planting, the tree was inoculated with truffle spores, and the surrounding soil was made less acidic by treating it with lime.

“This is one of the best-flavoured truffle species in the world and the potential for industry is huge,” said Thomas. “We planted the trees just to monitor their survival, but we never thought this Mediterranean species could actually grow in the UK – it’s an incredibly exciting development.”

̽��ֱ��researchers have attributed the fact that black truffles are able to grow so far outside their native Mediterranean habitat to climate change. “Different species respond to climate change on different scales and at different rates, and you often get an ecological mismatch,” said Büntgen. “For instance, insects can move quickly, while the vegetation they depend on may not. It’s possible that truffles are one of these fast-shifting species.”

“This cultivation has shown that the climatic tolerance of truffles is much broader than previously thought, but it’s likely that it’s only possible because of climate change, and some areas of the UK – including the area around Cambridge – are now suitable for the cultivation of this species,” said Thomas. “While truffles are a very valuable crop, together with their host trees, they are also a beneficial component for conservation and biodiversity.”

̽��ֱ��first harvested truffle, which weighed 16 grams, has been preserved for posterity, but in future, the truffles will be distributed to restaurants in the UK.

Reference:
Paul Thomas and Ulf Büntgen. ‘New UK truffle find as a result of climate change.’ Climate Research (2017). DOI: 10.3354/cr01494.

̽��ֱ��Mediterranean black truffle, one of the world’s most expensive ingredients, has been successfully cultivated in the UK, as climate change threatens its native habitat.

Even though humans have been eating truffles for centuries, we know remarkably little about how they grow and how they interact with their host trees.

Ulf Büntgen

Paul Thomas

Left: Bella with the host oak tree Right: Perigord black truffle

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes