The Truffle: A Changing Climate

There are many who have praised the truffle through the ages, from Pliny's statement (or warning) that it would be better to suffer a famine of wheat than a shortage of truffles, to the upscale gourmands of today who sometimes pay hundreds of dollars for a truffle dish. And why is this? Because the truffle is one food plant we have not yet domesticated even though its potency has been savored for thousands of years.

First of all, a brief explanation of what we are talking about. Truffles are a type of mushroom, broadly speaking, but narrowly speaking are not mushrooms. They grow underground, rather than sprouting up after a rain, and rely on sharp-nosed animals to root them out and eat them to spread their spores. Pigs were traditionally used, and are still employed in some areas although trained dogs are much more common. Truffles are mycorrhiza, a type of fungus that is symbiotic with plants. They are similar to the bacteria in your gut that help digest various types of food. They get fed, and you get fed. Mycorrhizas help plant roots break down specific things (such as insects) into nutrients that can be absorbed. The truffle itself is like any mushroom, the reproductive element of the fungus that is largely invisible to our eyes.

Truffles do not exist in a vacuum. They are carefully adapted to specific environments and fair poorly or not at all outside of those circumstances. There exist many different varieties, from the Italian white to the French black, to the Asian varieties such as the Chinese black. The French black, in particular, is highly prized as a commodity, selling in the $800 per pound range. Although fungi in general are all over and are symbiotic with almost every plant that has been studied, each species is very specific to its native environment.

There are those who might want to quibble about the lack of domestication of the truffle. Since the 1970's the French have used a technique for seeding spores in the roots of seedling trees that can result in truffle trees that, years down the line, may at some point yield truffles in good years. Variations on this technique have been adapted elsewhere, in the US predominantly in California and North Carolina, with the same results. Plant enough “truffle trees” under the right circumstances, water and nourish it properly, and eventually you get truffles. You have to have the right tree species, the right soil acidity and composition, the right precipitation (or at least irrigation), the right combination of temperature variation, and maintain it as such for years without visible results.

Now, domestication refers to a process of selectively breeding a population for desired traits, sometimes to the point that they can't survive in the wild. For example, Pliny referred to wheat, which was central to European agriculture. Its wild grass ancestor does not hold its seeds (grain) to the stalk; in fact, it wants it to scatter as much as possible, as easily as possible over as long of a period as possible. For our uses, we needed grains that wouldn't fall off the stalk, that were big and heavy and thus wouldn't scatter, and that all matured at the same time. Without human interference, wheat would virtually disappear even though its ancestral cousin (which still exists) does just fine on its own.

However, all of these changes were random mutations that were selectively bred for over thousands of years and positively reinforced through how our ancestors cultivated it. There's little evidence that we've had this same impact on truffles.

Part of the problem is that the truffle doesn't lure humans per se it lures pigs. It reeks (literally, the stronger the scent the more prized the truffle) in a way that drives female pigs wild. They root around the soil and find the buried treasure. Oddly enough, once out of the ground the truffles can provoke a strong reaction in humans as well. Which, as far as the fungus is concerned, is just as well because it primarily wants to be eaten. The whole idea is for the spores to be in spoor, so to speak, and eliminated in the forest around the right kind of trees of that forest.

However, where there is money to be found eventually science will be brought in to deal with a problem. One of the problems is that we just don't understand enough about fungi in general to know how to intentionally manipulate something like the lifecycle of the truffle. Accidental domestication has failed, but today there are new tools at the disposal of mycologists. Someday, someone will pay for fungal genomes to be sequenced and studied-- and this has to happen sooner, rather than later.

Remember that bit about exacting environmental conditions for fungi? Accelerating climate change can have a big impact on things like growing seasons, precipitation, etc. Although it appears that multiple fungi can help for the most part many plants, we don't know the limits of this adaptability. We can reasonably assume that all sorts of life have over the long run, overcome previous periods of climatic upheaval. However, adaptation takes a long time-- it must work on random mutations in the genes, with those few members of a population with slightly better adaptations surviving to maturity having more reproductively successful descendants...until conditions change again that turn advantages into disadvantages. However, this can play out over generations and huge areas, which render it of very little value over, say, the next couple of centuries in areas concerned with cultivating truffles. We know, for example, that around 1900 there were recipes involving pounds of truffles. Today, the total tonnage of truffle production is a small percent of what it was in previous years and there are far more people today to consume that smaller supply. Was this because of environmental degradation associated with the wars in the 20th Century, or other industrial sources of pollution, or overhunting, or overlogging, or some other change, or some combination of elements that must be untangled? This question needs to be answered for us to understand how to more easily cultivate the truffle and will be partially answered by sequencing the genes of the truffle and painstakingly matching up specific sequences with expressed proteins and figuring out which “junk” DNA helps regulate patterns of protein expression.

Proper understanding of truffle species' genomes will happen. Consumers with a lot of money are interested in them. Agriculturalists and horti-culturalists are interested in them. Scientists are beginning to become more interested in fungi in general and their interactions with plants. In ten years, not only will there be a wider variety of successful truffle farms spread across the globe, each with their own isolated populations in slightly varying conditions, but the tools used to sequence the genomes of rats, mice, fruit flies, humans, chimps and other animals will be brought to bear on this issue. Not only is there a commercial interest in furthering mycology specifically for truffles, but by doing so it will further the agro sciences in general. Their history, role in our diet, and recent redistribution all set them apart as ideal subjects to help understand more about mycorrhiza.