image: White truffles are the most expensive type of truffle. Credit: Wikipedia Commons
At the end of 19H In the 20th century, Professor Albert Bernhard Frank was commissioned by the Prussian Minister of Agriculture to investigate the possibility of cultivating truffles in Prussia. The most sought-after culinary truffle – the white truffle (Magnatum tuber) and black trufflemelanosporum tuber) – It occurs naturally only in Italy, Spain, France and some Eastern European countries. If the area of this fungus could be expanded, a gold mine would open up. Although Professor Frank never succeeded, he made some discoveries that turned the scientific world upside down.
Of course, Frank was not the first or only scientist to examine a truffle – or rather, under a microscope. Much was already known about this remarkable creature. For example, it was already known that a truffle is the fruiting body of the truffle fungus. The fruiting body produces spores for reproduction. You can compare it to the mycelium produced by many other fungi. Most truffles grow underground in the form of a network of fine fungal threads, also called hyphae. Furthermore, it was already known that truffles are always found near certain types of trees, including oaks and beech. What was inexplicable at the time was that the roots of these trees are partially enclosed in a fungal covering.
Frank does not owe his progressive visions to the technological revolution, with more powerful microscopes or more advanced protocols. No, what sets Frank apart from his predecessors is the depth and ingenuity of his explanations. He was the first to correctly explain the mycelium around plant roots: the plant and the fungus work together! The fungus uses its vast network of fine mycelial threads to extract nutrients such as nitrogen and phosphorus from the soil and provide them to the plant. In return, it receives sugars from the plant, which it produces through photosynthesis. This cooperation is mentioned Mycorrhizaemeaning “mushroom root”. It has also been shown that truffles are mycorrhizal fungi, which explains why they always occur near certain types of trees.
Although Frank was certainly right, his theory was initially disputed by much of the scientific community. In the 19H In the last century, fungi were seen primarily as pathogens. The idea that two completely different forms of life—plants and fungi—coexisted together was difficult to understand at the time within Darwinism, which focused primarily on competition between individuals. But now almost all of Frank’s mycorrhizal hypotheses have been experimentally proven—just a century after he first proposed them.
Today we know that about ninety percent of all plant species form mycorrhizae. In plants that cannot form mycorrhizae, this property is disabled, because the benefits to the plant do not outweigh the costs (they have to pay the fungi with sugar). For example, the large nettle grows in disturbed soil that is rich in nutrients. Since there is no competition with other plants and the nutrients are abundant, it is not beneficial for mycorrhizae to exist here. At the other end of the soil fertility spectrum, in very fertile soils that contain little phosphorus, there are also a number of plants that do not have mycorrhizae. They have evolved specialized roots that can absorb phosphorus more efficiently.
In fact, mycorrhizae played a crucial role in the emergence of plants on Earth. Fossils clearly show that 400 million years ago, when plants had not been on Earth for very long, plants already had numerous fungal roots. Without mycorrhizae, these primitive rootless plants would probably not have been able to establish themselves in the then poorly developed soil. Together with fungi, these plants revolutionized the Earth, from which we still harvest today, the most delicious of which, in my opinion, is truffles.
