Truffle Semiochemicals

The white truffle or Tuber magnatum is found mainly best known in the Langhe Piedmont region in northern Italy. It is also be found in Abruzzo, and in the hills in Tuscany and in the region of the Istria Croatia in the Motovun forest, and in Slovenia along the Dragonja, a 30-kilometre long river, and Rizana river.

Finding the perfect truffle isn’t as easy as it seems. Truffles are symbiotic fungi that develop underground in association with plant roots. The pictured truffle has been marked by the soils of the tree host and hence red color is present.

They also freely diffuse in the soil and mediate interactions with microorganisms and plant roots, potentially regulating a complex molecular dialogue among soil fauna and flora. The truffles are growing in a moist environments and its a question of the soil moisture content, growth rate, and most importantly the timing of finding it.

Truffles are subject to their host environment and it begins in the late summer when the spores begin. Truffles are fungi that produce fruiting bodies with spores sequestered in a spherical mass, below ground or close at the soils surface. This pattern suggests symbiotic association with plants may be an important in the evolution of truffle diversity.

In the photo, the moisture is obviously more dense on the outside and in the interior the veins are slightly drier. The hypogeous fruiting habit of the truffle are characterized by a low surface area-to-volume ratio, therefore a large number of spores are produced in a small packet of tissue. Furthermore, while epigeous fruiting bodies are directly exposed to weather, truffles are buffered against moisture and temperature fluctuations that might otherwise damage or inhibit development of spores.

Their scent is sensual, seductive and unique however, do not produce their aroma for the mere pleasure of humans. Truffle volatiles act as odorant cues for mammals and insects which are thus able to locate the precious fungi underground and spread their spores. Truffle spores have been found in the fecal deposits of rodents, marsupials, reptiles and gastropods, suggesting that these animals are important dispersal agents of truffle spores.

Truffles are sac fungi, a symbiotic fungi that strictly depend on other organisms to complete their life cycle. Indeed, unless they enter a symbiosis with plant roots and establish ectomycorrhizas (relationships with other roots or plants) truffles do not form fruiting bodies. Additionally, fruiting bodies do not spread their spores unless they are eaten by insects or mammals.

Truffles use volatile signals throughout their life cycle to regulate their interactions with other organisms and the role of truffle volatiles in nature has rarely been investigated. Truffles probably release small quantities of volatile chemicals, but when a truffle is damaged by insects or worms which are often found in truffles, many more volatiles are released.

Volatiles are magic of nature and can induce defense responses in neighboring plants. Such chemicals, which function in communication between and among species, as well as those that serve as messengers between members of the same species, are called semiochemicals from the Greek “semeion,” a mark or signal.

 

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