Thursday, November 4, 2010
Secret Sex Life of Truffles
Needless t0o say, if their dollar value were not so high, no one would care about the reproductive protocol of the truffle. Now at least we have a serious starting point and sooner or later, their husbandry will actually be mastered.
Once that happens, you can be sure that every oak tree in the world will be properly inoculated and we will have an ample supply.
It continues to be a fascinating story that is not about addiction but something so ephemeral as pure taste. In some way, it is wonderful that there is something that naturally exists which is highly sought after just because of the quality of taste. It is actually fairly readily available in the trade which tells you the thousands of pounds are been distributed. It also tells you that doubling supply will do little to quench demand. Such a doubling will actually just about tap every oak tree out there.
This means that natural production will never rise to meet demand. For that we will have to make production consistent and inevitable.
Secret sex life of truffles revealed
The secret and complex sex lives of black truffles, the rare fungi which are prized by chefs the world over, have been revealed in new research that may now help to make the delicacy more affordable.
By Richard Gray, Science Correspondent
Published: 8:00AM GMT 31 Oct 2010
Expensive delicacy black truffles Photo: Alamy
For thousands of years they have been prized by humans as an aphrodisiac, but it seems that black truffles may need a little help themselves when it comes to mating.
Black truffles, which grow underground on the roots of oak trees, have proved notoriously difficult to cultivate. For years the reason has been a mystery, as has the precise method by which the fungi spread.
Now researchers have solved the puzzle. They have found that truffles are either male or female, and they only reproduce sexually. This makes them distinct from other fungi which can self-fertilise and even reproduce asexually.
To make matters more difficult, they tend to become isolated in single-sex colonies growing many yards apart.
The findings go a long way towards explaining why black truffles, or Tuber melanosporum as it is known by scientists, are so rare and consequently so expensive.
France and , trufficulteurs enjoy varied success when they attempt to impregnate the roots of young oak trees with truffles. Italy
Even Prince Phillip, who spend £5,000 on specially-impregnated trees in the hope of growing black truffles at
Sandringham, has been frustrated by the results and earlier this month called in specialists to help.
The difficulty in growing Tuber melanosporum adds to the price, which can rise above £100 for a single specimen.
But Dr Francesco Paolocci, who led the latest research at the Plant Genetics Institute in
, said his team's findings could help increase the annual crop of truffles and even bring down the price. Perugia, Italy
He said: "It was long assumed that the truffle was like other fungi, but we know now that it needs the help of a partner. It has members of two different sexualities, a bit like male and female.
"But we found that individual trees are only colonised by a single sex of the fungi. Even when we started with a mixed colony, it quickly became dominated by one sex or the other.
"To produce the truffles, you have to have the two different sexual strains meeting in some way, but they can be quite far away from each other.
"We think that in nature animals, such as dogs or pigs, or insects can carry the spores from one colony to another allowing mating to take place.
"To cultivate it successfully, there needs to be more attention paid to the sexuality of black truffles when planting them to ensure there is an unbiased mix in truffle fields."
Truffles grow underground in a mutually-advantageous relationship with the roots of trees. The fungus colonises the tree roots early in their life, supplying them with nutrients and minerals while obtaining food from the roots.
Black truffles, often called Périgord truffles after the region in
where they are most commonly found, are typically harvested in autumn or winter and can reach up to three inches in diameter and weigh up to three ounces. France
The fruiting body of the fungus, which is the part that is so sought after by chefs around the world, occurs only on the maternal sex.
Truffle hunters use pigs, which have highly sensitive noses, or dogs to hunt out the pungent fungus from beneath the ground.
The concepts of male and female do not apply to fungi precisely, as their reproductive cycles can be highly complex.
Most species can reproduce asexually without the need for fertilisation and their genomes do not differ in the same way as higher animals do to distinguish males and females.
Fungi are instead characterised by mating type, which is determined by the production of a number of pheromones along with receptors that detect them.
Genetic testing has allowed scientists to begin to build up a picture of fungi mating types, and earlier this year Italian scientists sequenced the full genome of the black truffle.
That work revealed that black truffles are heterothallic, meaning that individuals can only be a single sex.
Subsequent work by Dr Paolocci and Dr Andrea Rubini, who is also based the Plant Genetics Institute, has now revealed fungus are also extremely fussy about mixing with the opposite sex and tend to form colonies of separate mating types.
Their findings, which are published in the scientific journal New Phytologist, also show that oak roots tend to be dominated by the maternal strain, while the paternal strain is found elsewhere in the soil.
Dr Paolocci added: "So far, when cultivating this fungus, people have overlooked the sexuality of the truffles. They take the roots of the trees that are colonised by the fungus and plant it around a truffle ground.
"But in order to have a productive truffle ground we need to have both the male and female strains.
"We have genetic markers that help us identify the male and female strains, and this can be used to increase production. It could help bring the price of these fungus down."
Black truffles, nicknamed 'black diamonds', were long thought in the
Middle East to have medicinal qualities and the ancient Romans and Greeks also considered them to be an aphrodisiac.
According to the French Federation of Trufficulteurs only around 30% of trees that have been impregnated with truffle fungi will produce a crop.
Michel Courvoisier, director of the French Federation of Trufficulteurs, said: "We have no definitive answer about why. We hope that the recent discoveries, such as the mating type genes, will allow us to understand why sometimes the plantations are non-productive.
"Unfortunately, a better mastering of growing conditions will not quickly affect production – truffles are a slow emerging fungi."