A truffle is the fruiting body of a subterranean ascomycete

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

, predominantly one of the many species of the genus ''

Tuber Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...

''. In addition to ''Tuber'', many other genera of fungi are classified as truffles including '' Geopora'', '' Peziza'', '' Choiromyces'', '' Leucangium'', and over a hundred others. These genera belong to the class Pezizomycetes and the

Pezizales The Pezizales are an order of the subphylum Pezizomycotina within the phylum Ascomycota. The order contains 16 families, 199 genera, and 1683 species. It contains a number of species of economic importance, such as morels, the black and white ...

order. Several truffle-like basidiomycetes are excluded from Pezizales, including ''

Rhizopogon ''Rhizopogon'' is a genus of ectomycorrhizal basidiomycetes in the family Rhizopogonaceae. Species form hypogeous sporocarps commonly referred to as " false truffles". The general morphological characters of ''Rhizopogon'' sporocarps are a si ...

'' and ''Glomus''. Truffles are ectomycorrhizal fungi, so they are usually found in close association with tree roots. Spore dispersal is accomplished through fungivores, animals that eat fungi. These fungi have significant ecological roles in nutrient cycling and drought tolerance. Some truffle species are highly prized as food. French gastronome Jean Anthelme Brillat-Savarin called truffles "the diamond of the kitchen". Edible truffles are used in Italian,

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

and numerous other national . Truffles are cultivated and harvested from natural environments.

History

Antiquity

The first mention of truffles appears in the inscriptions of the neo-Sumerians regarding their

Amorite The Amorites (; sux, 𒈥𒌅, MAR.TU; Akkadian: 𒀀𒈬𒊒𒌝 or 𒋾𒀉𒉡𒌝/𒊎 ; he, אֱמוֹרִי, 'Ĕmōrī; grc, Ἀμορραῖοι) were an ancient Northwest Semitic-speaking people from the Levant who also occupied lar ...

enemy's eating habits (

Third Dynasty of Ur The Third Dynasty of Ur, also called the Neo-Sumerian Empire, refers to a 22nd to 21st century BC ( middle chronology) Sumerian ruling dynasty based in the city of Ur and a short-lived territorial-political state which some historians consider t ...

, 20th century BCE) and later in writings of

Theophrastus Theophrastus (; grc-gre, Θεόφραστος ; c. 371c. 287 BC), a Greek philosopher and the successor to Aristotle in the Peripatetic school. He was a native of Eresos in Lesbos.Gavin Hardy and Laurence Totelin, ''Ancient Botany'', Routle ...

in the 4th century BCE. In classical times, their origins were a mystery that challenged many;

Plutarch Plutarch (; grc-gre, Πλούταρχος, ''Ploútarchos''; ; – after AD 119) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo in Delphi. He is known primarily for hi ...

and others thought them to be the result of lightning, warmth, and water in the soil, while

Juvenal Decimus Junius Juvenalis (), known in English as Juvenal ( ), was a Roman poet active in the late first and early second century CE. He is the author of the collection of satirical poems known as the '' Satires''. The details of Juvenal's life ...

thought thunder and rain to be instrumental in their origin.

Cicero Marcus Tullius Cicero ( ; ; 3 January 106 BC – 7 December 43 BC) was a Roman statesman, lawyer, scholar, philosopher, and academic skeptic, who tried to uphold optimate principles during the political crises that led to the esta ...

deemed them children of the earth, while

Dioscorides Pedanius Dioscorides ( grc-gre, Πεδάνιος Διοσκουρίδης, ; 40–90 AD), “the father of pharmacognosy”, was a Greek physician, pharmacologist, botanist, and author of '' De materia medica'' (, On Medical Material) —a 5-vo ...

thought they were tuberous roots.

Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus ( legendary) , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg , map_caption ...

and Thracia in the Classical period identified three kinds of truffles: '' Tuber melanosporum'', '' T. magnificus'', and '' T. magnatum''. The Romans instead used a variety of fungus called terfez, also sometimes called a "desert truffle". Terfez used in Rome came from Lesbos,

Carthage Carthage was the capital city of Ancient Carthage, on the eastern side of the Lake of Tunis in what is now Tunisia. Carthage was one of the most important trading hubs of the Ancient Mediterranean and one of the most affluent cities of the classi ...

, and especially

Libya Libya (; ar, ليبيا, Lībiyā), officially the State of Libya ( ar, دولة ليبيا, Dawlat Lībiyā), is a country in the Maghreb region in North Africa. It is bordered by the Mediterranean Sea to the north, Egypt to the east, Suda ...

, where the coastal climate was less dry in ancient times. Their substance is pale, tinged with rose. Unlike truffles, terfez have little inherent flavour. The Romans used the terfez as a flavour carrier because the terfez tends to absorb surrounding flavours. Because Ancient Roman cuisine used many spices and flavourings, the terfez may have been appropriate in that context.

Middle Ages

Truffles were rarely used during the

Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...

. Truffle hunting is mentioned by

Bartolomeo Platina Bartolomeo Sacchi (; 1421 – 21 September 1481), known as Platina (in Italian ''il Platina'' ) after his birthplace (Piadena), and commonly referred to in English as Bartolomeo Platina, was an Italian Renaissance humanist writer and gastro ...

, the papal historian, in 1481, when he recorded that the sows of Notza were without equal in hunting truffles, but they should be muzzled to prevent them from eating the prize.

Renaissance and modernity

During the

Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ide ...

, truffles regained popularity in Europe and were honoured at the court of King

Francis I of France Francis I (french: François Ier; frm, Francoys; 12 September 1494 – 31 March 1547) was King of France from 1515 until his death in 1547. He was the son of Charles, Count of Angoulême, and Louise of Savoy. He succeeded his first cousin on ...

. They were popular in Parisian markets in the 1780s, imported seasonally from truffle grounds, where peasants had long enjoyed them.

Brillat-Savarin Jean Anthelme Brillat-Savarin (; 1 April 1755, Belley, Ain – 2 February 1826, Paris) was a French lawyer and politician, who, as the author of ''The Physiology of Taste'' (''Physiologie du Goût''), gained fame as an epicure and gastronome: " ...

(1825) noted that they were so expensive they appeared only at the dinner tables of great nobles and kept women. They were sometimes served with turkey.

Cultivation

Truffles long eluded techniques of domestication, as Jean-Anthelme Brillat-Savarin (1825) noted:

The most learned men have sought to ascertain the secret and fancied they discovered the seed. Their promises, however, were vain, and no planting was ever followed by a harvest. This perhaps is all right, for as one of the great values of truffles is their dearness, perhaps they would be less highly esteemed if they were cheaper.English translation

Truffles can be cultivated. As early as 1808, attempts to cultivate truffles, known in French as , were successful. People had long observed that truffles were growing among the roots of certain trees, and in 1808,

Joseph Talon Joseph is a common male given name, derived from the Hebrew Yosef (יוֹסֵף). "Joseph" is used, along with "Josef", mostly in English, French and partially German languages. This spelling is also found as a variant in the languages of the mo ...

, from Apt ( of

Vaucluse Vaucluse (; oc, Vauclusa, label= Provençal or ) is a department in the southeastern French region of Provence-Alpes-Côte d'Azur. It had a population of 561,469 as of 2019.France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

, had the idea of transplanting some seedlings that he had collected at the foot of oak trees known to host truffles in their root system. For discovering how to cultivate truffles, some sources now give priority to Pierre II Mauléon (1744–1831) of

Loudun Loudun (; ; Poitevin: ''Loudin'') is a commune in the Vienne department and the region of Nouvelle-Aquitaine, western France. It is located south of the town of Chinon and 25 km to the east of the town Thouars. The area south of Loudun i ...

(in western France), who began to cultivate truffles around 1790. Mauléon saw an "obvious symbiosis" between the oak tree, the rocky soil, and the truffle and attempted to reproduce such an environment by taking acorns from trees known to have produced truffles and sowing them in chalky soil. His experiment was successful, with truffles found in the soil around the newly grown oak trees years later. In 1847, Auguste Rousseau of Carpentras (in

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. Si ...

Others imitated these successful attempts in France and Italy. In the late 19th century, an epidemic of phylloxera destroyed many of the vineyards in southern France. Another epidemic killed most of the

silkworm The domestic silk moth (''Bombyx mori''), is an insect from the moth family Bombycidae. It is the closest relative of '' Bombyx mandarina'', the wild silk moth. The silkworm is the larva or caterpillar of a silk moth. It is an economically ...

s there, too, making the fields of

mulberry ''Morus'', a genus of flowering plants in the family Moraceae, consists of diverse species of deciduous trees commonly known as mulberries, growing wild and under cultivation in many temperate world regions. Generally, the genus has 64 ident ...

trees useless. Trufficulture became an important source of income for those affected. The calcareous and exposed vineyard soils were well-suited to the cultivation of truffles. By 1890, truffières (truffle plantations) covered 750 km² of land in France, and 2,000 tonnes of truffles were produced in that year. From the 19th century to the present, truffle production fell by 97–99% to 20–50 tonnes annually. Reasons given for this decline include the

Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...

, the subsequent

rural flight Rural flight (or rural exodus) is the migratory pattern of peoples from rural areas into urban areas. It is urbanization seen from the rural perspective. In industrializing economies like Britain in the eighteenth century or East Asia in th ...

and the multiple European wars of the 20th century, which reduced the rural population. For example,

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

resulted in the mobilisation of 65% of the agricultural workers from the region of Lot alone. Knowledge of truffle cultivation, the soil and the seasons was lost along with the people. Another consequence was no more grazing sheep or shepherds who pruned trees for feed and fuelwood, so former truffle plantations turned into closed forests that no longer produced truffles. Truffles were once sold at weekly markets (bi-weekly in the case of a market in Martel, Lot) and in quantities of two to six tonnes in good weeks, but only

Lalbenque Lalbenque (; oc, L'Albenca) is a commune in the Lot department in south-western France. See also *Communes of the Lot department The following is a list of the 313 communes An intentional community is a voluntary residential community w ...

and Limogne today have weekly truffle markets. Prices have increased so that truffles, once seen as a food of the middle class, have become a luxury. The situation changed in the late 1960s and early 1970s, with researchers in France and Italy establishing mycorrhizas with truffle spores. Beginning from the 1980s, truffle plantations are compensating for some of the decline in wild truffles, and exist in various countries including France, Italy, Spain and Australia. About 80% of the truffles now produced in France come from specially planted truffle groves. Investments in cultivated plantations are underway in many parts of the world using controlled irrigation for regular and resilient production. A critical phase of the cultivation is the quality control of the mycorrhizal plants. Between 7 and 10 years are needed for the truffles to develop their mycorrhizal network, and only after that do the host plants come into production. Complete soil analysis to avoid contamination by other dominant fungi and very strict control of the formation of mycorrhizae are necessary to ensure the success of a plantation. Total investment per hectare for an irrigated and barrier-sealed plantation (against wild boars) can cost up to €10,000. Considering the level of initial investment and the maturity delay, farmers who have not taken care of both soil conditions and seedling conditions are at high risk of failure.

New Zealand and Australia

The first black truffles ('' Tuber melanosporum'') to be produced in the Southern Hemisphere were harvested in Gisborne, New Zealand in 1993. New Zealand's first burgundy truffle was found in July 2012 at a Waipara truffle farm. It weighed 330 g and was found by the farm owner's beagle. In 1999, the first Australian truffles were harvested in

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

, the result of eight years of work. Trees were inoculated with the truffle fungus to create a local truffle industry. Their success and the value of the resulting truffles has encouraged a small industry to develop. Truffle production has expanded into the colder regions of Victoria,

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

and

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to t ...

. In 2014, over of truffles were harvested by Truffle Hill, Manjimup, Western Australia. In June 2014, A grower harvested Australia's largest truffle from their property at

Robertson Robertson may refer to: People * Robertson (surname) (includes a list of people with this name) * Robertson (given name) * Clan Robertson, a Scottish clan * Robertson, stage name of Belgian magician Étienne-Gaspard Robert (1763–1837) Place ...

, in the Southern Highlands of

. It was a French black perigord fungus weighing in at and was valued at over $2,000 per kilogram.

United States

Périgord truffles were first farmed in Tennessee in 2007. At its peak in the 2008–2009 season, one farm produced about 200 pounds of truffles, but Eastern filbert blight almost entirely wiped out the hazel trees by 2013 and production dropped, essentially ending the business. Eastern filbert blight similarly destroyed the orchards of other once-promising commercial farms in East Tennessee, while newer farms in California, North Carolina, Oregon, and Arkansas were started. , the Appalachian truffle (''Tuber canaliculatum'') was being developed as a potential market.

Etymology

The origin of the word "truffle" is from the Tamazight language in North Africa, where the truffle is native to the Atlas Mountains. In Moroccan Tamazight, the "truffle" is called ''tireffas'', which comes from the verb ''youfess'', meaning "to bury," referring to how deeply rooted truffles are under the soil. Other sources also attribute "truffle" to originate from the Latin term , meaning "swelling" or "lump", which became ''tufer.'' However, the Tamazight term predates the Latin term, and is phonologically closer to the various European terms used today: Danish , Dutch , English truffle, French , German , Greek τρούφα ''trúfa'', Italian , Polish , Romanian , Spanish , and Swedish . Additionally, in Moroccan Arabic, the term used is ''tirfa'' (ترفة). The German word ("potato") is derived from the Italian term for truffle because of superficial similarities. In Portuguese, the words and are synonyms, the latter closer to the Latin term.

Phylogeny

Phylogenetic analysis has demonstrated the

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

of the ectomycorrhizal trophic mode in diverse fungi. The subphylum,

Pezizomycotina Pezizomycotina make up most of the Ascomycota fungi and include most lichenized fungi too. Pezizomycotina contains the filamentous ascomycetes and is a subdivision of the Ascomycota (fungi that form their spores in a sac-like ''ascus''). It is mo ...

, containing the order Pezizales, is approximately 400 million years old. Within the order Pezizales, subterranean fungi evolved independently at least fifteen times. Contained within Pezizales are the families

Tuberaceae The Tuberaceae () are a family of mycorrhizal fungi in the order Pezizales, that evolved during or after the first major radiation of Angiosperms in the Jurassic period (140–180 million years ago, Mya). It includes the genus ''Tuber'', which i ...

, Pezizaceae, Pyronematacae, and

Morchellaceae The Morchellaceae are a family of ascomycete fungi in the order Pezizales. According to a standard reference work, the family has contained at least 49 species distributed among four genera. However, in 2012, five genera that produce ascoma that ...

. All of these families contain lineages of subterranean or truffle fungi. The oldest ectomycorrhizal fossil is from the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...

about 50 million years ago. This indicates that the soft bodies of ectomycorrhizal fungi do not easily fossilise. Molecular clockwork has suggested the evolution of ectomycorrhizal fungi occurred approximately 130 million years ago. The evolution of subterranean fruiting bodies has arisen numerous times within the Ascomycota, Basidiomycota, and Glomeromycota. For example, the genera ''

'' and ''

Hysterangium ''Hysterangium'' is a genus of truffle-like fungi in the family Hysterangiaceae. The genus is widespread, especially in temperate regions, and contains more than 60 species. ''Hysterangium'' was circumscribed by Italian mycologist Carlo Vit ...

'' of Basidiomycota both form subterranean fruiting bodies and play similar ecological roles as truffle forming ascomycetes. The ancestors of the Ascomycota genera ''Geopora'', ''Tuber'', and ''Leucangium'' originated in Laurasia during the Paleozoic era. Phylogenetic evidence suggests that most subterranean fruiting bodies evolved from above-ground mushrooms. Over time mushroom stipes and caps were reduced, and caps began to enclose reproductive tissue. The dispersal of sexual spores then shifted from wind and rain to utilising animals. The

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological s ...

and

biogeography Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

of the genus ''Tuber'' was investigated in 2008 using internal transcribed spacers (ITS) of nuclear DNA and revealed five major

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

s (Aestivum, Excavatum, Rufum, Melanosporum and Puberulum); this was later improved and expanded in 2010 to nine major clades using large subunits (LSU) of

mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

. The Magnatum and Macrosporum clades were distinguished as distinct from the Aestivum clade. The Gibbosum clade was resolved as distinct from all other clades, and the Spinoreticulatum clade was separated from the Rufum clade. The truffle habit has evolved independently among several basidiomycete genera. Phylogenetic analysis has revealed that basidiomycete subterranean fruiting bodies, like their ascomycete counterparts, evolved from above ground mushrooms. For example, ''Rhizopogon'' species likely arose from an ancestor shared with '' Suillus'', a mushroom-forming genus. Studies have suggested that selection for subterranean fruiting bodies among ascomycetes and basidiomycetes occurred in water-limited environments.

Species

Black

Tuber brumale - Vue sur la tranche coupée

The black truffle or black Périgord truffle (''Tuber melanosporum''), the second-most commercially valuable species, is named after the Périgord region in France. Black truffles associate with oaks, hazelnut, cherry, and other deciduous trees and are harvested in late autumn and winter. The genome sequence of the black truffle was published in March 2010.

Summer or burgundy

The black summer truffle (''Tuber aestivum'') is found across Europe and is prized for its culinary value. Burgundy truffles (designated '' Tuber uncinatum'', but the same species) are harvested in autumn until December and have aromatic flesh of a darker colour. These are associated with various trees and shrubs.

White

Tuber magnatum, the high-value ''white truffle'' (''tartufo bianco d'Alba'' in Italian) is found mainly in the

Langhe The Langhe (; ''Langa'' is from old dialect Mons Langa et Bassa Langa) is a hilly area to the south and east of the river Tanaro in the province of Cuneo and in the province of Asti in Piedmont, northern Italy. It is famous for its wines, c ...

and Montferrat areas of the

Piedmont it, Piemontese , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = , demographics1_title2 ...

region in northern

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

, and most famously, in the countryside around the cities of

Alba ''Alba'' ( , ) is the Scottish Gaelic name for Scotland. It is also, in English language historiography, used to refer to the polity of Picts and Scots united in the ninth century as the Kingdom of Alba, until it developed into the Kin ...

and

Asti Asti ( , , ; pms, Ast ) is a '' comune'' of 74,348 inhabitants (1-1-2021) located in the Piedmont region of northwestern Italy, about east of Turin in the plain of the Tanaro River. It is the capital of the province of Asti and it is deeme ...

. A large percentage of Italy's white truffles also come from

Molise it, Molisano (man) it, Molisana (woman) , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 ...

Whitish

The " whitish truffle" (''Tuber borchii'') is a similar species native to

Tuscany it, Toscano (man) it, Toscana (woman) , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = Citizenship , demographics1_footnotes = , demographics1_title1 = Italian , demogra ...

Abruzzo , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1 ...

Romagna Romagna ( rgn, Rumâgna) is an Italian historical region that approximately corresponds to the south-eastern portion of present-day Emilia-Romagna, North Italy. Traditionally, it is limited by the Apennines to the south-west, the Adriatic to th ...

Umbria it, Umbro (man) it, Umbra (woman) , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = , ...

, the

Marche Marche ( , ) is one of the twenty regions of Italy. In English, the region is sometimes referred to as The Marches ( ). The region is located in the central area of the country, bordered by Emilia-Romagna and the republic of San Marino to the ...

, and

. It is reportedly not as aromatic as those from Piedmont, although those from

Città di Castello Città di Castello (); "Castle Town") is a city and '' comune'' in the province of Perugia, in the northern part of Umbria. It is situated on a slope of the Apennines, on the flood plain along the upper part of the river Tiber. The city is north o ...

are said to come quite close.

Other ''Tuber''

A less common truffle is "garlic truffle" (''

Tuber macrosporum ''Tuber macrosporum'', commonly known as the smooth black truffle, is a species of edible truffle in the family Tuberaceae. Found in Europe, and common in central Italy, the truffle was described as new to science by Italian mycologist Carlo Vi ...

''). In the U.S.

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Thou ...

, several species of truffle are harvested both recreationally and commercially, most notably, the '' Leucangium carthusianum'', Oregon black truffle; ''

Tuber gibbosum ''Tuber gibbosum'' is a species of truffle in the genus ''Tuber''. It is found in the Pacific Northwest region of the United States, where it grows in an ectomycorrhizal association with Douglas-fir. It is commercially collected between as ear ...

'', Oregon spring white truffle; and '' Tuber oregonense'', the Oregon winter white truffle. '' Kalapuya brunnea'', the Oregon brown truffle, has also been commercially harvested and is of culinary note. The pecan truffle (''Tuber lyonii'') syn. ''texense'' is found in the

Southern United States The Southern United States (sometimes Dixie, also referred to as the Southern States, the American South, the Southland, or simply the South) is a geographic and cultural region of the United States of America. It is between the Atlantic Ocean ...

, usually associated with pecan trees. Chefs who have experimented with them agree "they are very good and have potential as a food commodity". Although pecan farmers used to find them along with pecans and discard them, considering them a nuisance, they sell for about $160 a pound and have been used in some gourmet restaurants.

Beyond ''Tuber''

The term "truffle" has been applied to several other genera of similar underground fungi. The genera '' Terfezia'' and '' Tirmania'' of the family Terfeziaceae are known as the "desert truffles" of Africa and the Middle East. ''

Pisolithus tinctorius ''Pisolithus arhizus'' is a widespread earth-ball like fungus, which may in fact be several closely related species. Common names include dead man's foot and dyeball. It is known in Australia as the horse dung fungus, in South Africa as perde ...

'', which was historically eaten in parts of

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...

, is sometimes called "Bohemian truffle". '' Geopora'' spp. are important ectomycorrhizal partners of trees in woodlands and forests throughout the world. ''Pinus edulis'', a widespread pine species of the Southwest US, is dependent on ''Geopora'' for nutrient and water acquisition in arid environments. Like other truffle fungi, ''Geopora'' produces subterranean sporocarps as a means of sexual reproduction. '' Geopora cooperi'', also known as pine truffle or fuzzy truffle, is an edible species of this genus. Rhizopogon rubescens

'' spp. are ectomycorrhizal members of the Basidiomycota and the order

Boletales The Boletales are an order of Agaricomycetes containing over 1300 species with a diverse array of fruiting body types. The boletes are the best known members of this group, and until recently, the Boletales were thought to only contain boletes. T ...

, a group of fungi that typically form mushrooms. Like their ascomycete counterparts, these fungi can create truffle-like fruiting bodies. ''Rhizopogon'' spp. are ecologically important in coniferous forests where they associate with various pines, firs, and Douglas fir. In addition to their ecological importance, these fungi hold economic value, as well. ''Rhizopogon'' spp. are commonly used to inoculate coniferous seedlings in nurseries and during reforestation. ''

'' spp. are ectomycorrhizal members of the Basidiomycota and the order

Hysterangiales The Hysterangiales are an order of fungi in the class Agaricomycetes, subclass Phallomycetidae. According to one 2008 estimate, the order contains five families, 18 genera Genus ( plural genera ) is a taxonomic rank used in the biological ...

that form sporocarps similar to true truffles. These fungi form mycelial mats of vegetative hyphae that may cover 25-40% of the forest floor in Douglas fir forests, thereby contributing to a significant portion of the biomass present in soils. Like other ectomycorrhizal fungi, ''Hysterangium'' spp. play a role in nutrient exchange in the nitrogen cycle by accessing nitrogen unavailable to host plants and acting as nitrogen sinks in forests. '' Glomus'' spp. are arbuscular mycorrhizae of the phylum Glomeromycota within the order Glomerales. Members of this genus have low host specificity, associating with a variety of plants including hardwoods, forbs, shrubs, and grasses. These fungi commonly occur throughout the Northern Hemisphere. Members of the genus ''

Elaphomyces ''Elaphomyces'' (‘deer truffles’) is a genus of hypogeous fungi in the family Elaphomycetaceae. The widespread genus contains 25 truffle-like species. ''Elaphomyces'' is one of the most important ectomycorrhizal fungal genera in temperate ...

'' are commonly mistaken for truffles.

Ecology

The

mycelia Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates in ...

of truffles form

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or para ...

, mycorrhizal relationships with the roots of several tree species, including

beech Beech (''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia, and North America. Recent classifications recognize 10 to 13 species in two distinct subgenera, ''Engleriana'' and ''Fagus''. The ''Engl ...

birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' cont ...

, hazel, hornbeam, oak,

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family (biology), family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanic ...

, and poplar. Mutualistic ectomycorrhizal fungi such as truffles provide valuable nutrients to plants in exchange for

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may o ...

s. Ectomycorrhizal fungi cannot survive in the soil without their plant hosts. In fact, many of these fungi have lost the

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

s necessary for obtaining carbon through other means. For example, truffle fungi have lost their ability to degrade the cell walls of plants, limiting their capacity to decompose plant litter. Plant hosts can also depend on their associated truffle fungi. ''Geopora'', ''Peziza'', and ''Tuber'' spp. are vital in the establishment of oak communities. ''Tuber'' species prefer argillaceous or

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an ad ...

soils that are well drained and neutral or alkaline. ''Tuber'' truffles fruit throughout the year, depending on the species, and can be found buried between the

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead organic material and its constituent ...

and the soil. Most fungal biomass is found in the humus and litter layers of soil. Pezizales, Ascomycota Life Cycle

Most truffle fungi produce both asexual spores (mitospores or conidia) and sexual spores (meiospores or

ascospore An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera ...

s/ basidiospores). Conidia can be produced more readily and with less energy than ascospores and can disperse during disturbance events. Production of ascospores is energy intensive because the fungus must allocate resources to the production of large sporocarps. Ascospores are borne within sac-like structures called asci, which are contained within the sporocarp. Because truffle fungi produce their sexual fruiting bodies underground, spores cannot be spread by wind and water. Therefore, nearly all truffles depend on mycophagous animal vectors for spore dispersal. This is analogous to the dispersal of seeds in fruit of angiosperms. When the ascospores are fully developed, the truffle exudes volatile compounds that attract animal vectors. For successful dispersal, these spores must survive passage through the digestive tracts of animals. Ascospores have thick walls composed of

chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...

to help them endure the environment of animal guts. Animal vectors include birds, deer, and rodents such as

vole Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...

squirrel Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. ...

s, and chipmunks. Many species of trees, such as '' Quercus garryana'', are dependent on the dispersal of sporocarps to inoculate isolated individuals. For example, the acorns of ''Q. garryana'' may be carried to new territory that lacks the necessary mycorrhizal fungi for establishment. Some mycophagous animals depend on truffles as their dominant food source. Flying squirrels, '' Glaucomys sabrinus'', of North America play a three-way symbiosis with truffles and their associated plants. ''G. sabrinus'' is particularly adapted to finding truffles using its refined sense of smell, visual clues, and long-term memory of prosperous populations of truffles. This intimacy between animals and truffles indirectly influences the success of mycorrhizal plant species. After ascospores are dispersed, they remain dormant until germination is initiated by exudates excreted from host plant roots. Following germination, hyphae form and seek out the roots of host plants. Arriving at roots, hyphae begin to form a mantle or sheath on the outer surface of root tips. Hyphae then enter the root cortex intercellularly to form the Hartig net for nutrient exchange. Hyphae can spread to other root tips colonising the entire root system of the host. Over time, the truffle fungus accumulates sufficient resources to form fruiting bodies. Rate of growth is correlated with increasing photosynthetic rates in the spring as trees leaf out.

Nutrient exchange

Truffle fungi receive carbohydrates from their host plants, providing them with valuable micro- and macronutrients. Plant macronutrients include

potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

, and

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...

. In contrast, micronutrients include

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

, and

chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride s ...

. In truffle fungi, as in all ectomycorrhizae, the majority of nutrient exchange occurs in the Hartig net, the intercellular hyphal network between plant root cells. A unique feature of ectomycorrhizal fungi is the formation of the mantle on the outer surface of fine roots. Truffles have been suggested to co-locate with the orchid species '' Epipactis helleborine'' and ''

Cephalanthera damasonium ''Cephalanthera damasonium'', the white helleborine, is a species of orchid. It is widespread across much of Europe, the Middle East and Asia. ''Cephalanthera damasonium'' is the type species of the genus ''Cephalanthera''. Description ''Cep ...

'', though this is not always the case.

Nutrient cycling

Truffle fungi are ecologically important in nutrient cycling. Plants obtain nutrients via their fine roots. Mycorrhizal fungi are much smaller than fine roots, so they have a higher surface area and a greater ability to explore soils for nutrients. Acquisition of nutrients includes the uptake of phosphorus, nitrate or ammonium, iron,

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...

, and other ions. Many ectomycorrhizal fungi form fungal mats in the upper layers of soils surrounding host plants. These mats have significantly higher carbon and fixed nitrogen concentrations than surrounding soils. Because these mats are nitrogen sinks, leaching of nutrients is reduced. Mycelial mats can also help maintain the structure of soils by holding organic matter in place and preventing

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

. Often, these networks of mycelium provide support for smaller organisms in the soil, such as bacteria and microscopic

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

s. Bacteria feed on the exudates released by mycelium and colonise the soil surrounding them. Microscopic arthropods such as mites feed directly on mycelium and release valuable nutrients for the uptake of other organisms. Thus, truffle fungi and other ectomycorrhizal fungi facilitate a complex system of nutrient exchange between plants, animals, and microbes.

Importance in arid-land ecosystems

Plant community structure is often affected by the availability of compatible mycorrhizal fungi. In arid-land ecosystems, these fungi become essential for the survival of their host plants by enhancing the ability to withstand drought. A foundation species in arid-land ecosystems of the Southwest United States is '' Pinus edulis'', commonly known as pinyon pine. ''P. edulis'' associates with the subterranean fungi ''Geopora'' and ''Rhizopogon''. As global temperatures rise, so does the occurrence of severe droughts, detrimentally affecting the survival of aridland plants. This variability in climate has increased the mortality of ''P. edulis''. Therefore, the availability of compatible mycorrhizal inoculum can greatly affect the successful establishment of ''P. edulis'' seedlings. Associated ectomycorrhizal fungi will likely play a significant role in the survival of ''P. edulis'' with continuing global

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

Extraction

Because truffles are subterranean, they are often located with the help of an animal (sometimes called a truffler) possessing a refined sense of smell. Traditionally, pigs have been used to extract truffles. Both the female pig's natural truffle-seeking and her intent to eat the truffle were thought to be due to a compound within the truffle similar to androstenol, the sex pheromone of boar saliva, to which the sow is keenly attracted. Studies in 1990 demonstrated that the compound actively recognised by both truffle pigs and dogs is

dimethyl sulfide Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula (CH3)2S. Dimethyl sulfide is a flammable liquid that boils at and has a characteristic disagreeable odor. It is a component of the smell produced from co ...

. In Italy, the use of pigs to hunt truffles has been prohibited since 1985 because of damage caused by animals to truffle

during the digging that dropped the production rate of the area for some years. An alternative to truffle pigs are dogs. Dogs offer an advantage because they do not have a strong desire to eat truffles, so they can be trained to locate sporocarps without digging them up. Pigs attempt to dig up truffles. Fly species of the genus '' Suilla'' can also detect the volatile compounds associated with subterranean fruiting bodies. These flies lay their eggs above truffles to provide food for their young. At ground level, ''Suilla'' flies can be seen flying above truffles.

Volatile constituents

The mycelia or fruiting bodies release the volatile constituents responsible for the natural aroma of truffles or derive from truffle-associated

microbe A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

s. The chemical ecology of truffle volatiles is complex, interacting with plants, insects, and mammals, which contribute to

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

dispersal. Depending on the truffle species, lifecycle, or location, they include: *

Sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...

volatiles, which occur in all truffle species, such as dimethyl mono- (DMS), di- (DMDS) and tri- (DMTS) sulfides, as well as 2-methyl-4,5-dihydrothiophene, characteristic of the white truffle ''T. borchii'' and 2,4-Dithiapentane occurring in all species but mostly characteristic of the white truffle ''T. magnatum''. Some very aromatic white truffles are notably pungent, even irritating the eye when cut or sliced. * Metabolites of nonsulfur

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...

constituents (simple and branched-chain

hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...

) such as

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene ...

(produced by mycelia of white truffles affecting root architecture of host tree), as well as 2-methylbutanal, 2-methylpropanal, and 2-phenylethanol (also common in baker's yeast). *

Fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, f ...

-derived volatiles (C8-alcohols and

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl gro ...

s with a characteristic fungal odor, such as 1-octen-3-ol and 2-octenal). The former is derived from

linoleic acid Linoleic acid (LA) is an organic compound with the formula COOH(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are ''cis''. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid. ...

and produced by mature white truffle ''T. borchii''. *

Thiophene Thiophene is a heterocyclic compound with the formula C4H4S. Consisting of a planar five-membered ring, it is aromatic as indicated by its extensive substitution reactions. It is a colorless liquid with a benzene-like odor. In most of its reacti ...

derivatives appear to be produced by bacterial symbionts living in the truffle body. The most abundant of these, 3-methyl, 4-5 dihydrothiophene, contributes to the white truffle's aroma. Several truffle species and varieties are differentiated based on their relative contents or absence of

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds la ...

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again ...

s or alcohols, respectively. The sweaty-musky aroma of truffles is similar to that of the pheromone androstenol that also occurs in humans. , the volatile profiles of seven black and six white truffle species have been studied.

Culinary use

Shaved black truffles with pasta - Spago Las Vegas - March 2022 - Sarah Stierch

Because of their high price and their strong aroma, truffles are used sparingly. Supplies can be found commercially as unadulterated fresh produce or preserved, typically in a light brine. Their chemical compounds infuse well with fats such as butter, cream, cheeses, avocados, and coconut cream. As the volatile aromas dissipate quicker when heated, truffles are generally served raw and shaved over warm, simple foods where their flavour will be highlighted, such as buttered

pasta Pasta (, ; ) is a type of food typically made from an unleavened dough of wheat flour mixed with water or eggs, and formed into sheets or other shapes, then cooked by boiling or baking. Rice flour, or legumes such as beans or lentils, ...

or eggs. Thin truffle slices may be inserted into meats, under the skins of roasted fowl, in '' foie gras'' preparations, in '' pâtés'', or in stuffings. Some speciality

cheese Cheese is a dairy product produced in wide ranges of flavors, textures, and forms by coagulation of the milk protein casein. It comprises proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. During productio ...

s contain truffles, as well. Truffles are also used for producing truffle salt and truffle honey. While chefs once peeled truffles, in modern times, most restaurants brush the truffle carefully and shave it or dice it with the skin on to make the most of the valuable ingredient. Some restaurants stamp out circular discs of truffle flesh and use the skins for sauces. Truffle olive oil with Tuber melanosporum

Truffle olive oil with Tuber melanosporum

Oil

Truffle oil is used as a lower-cost and convenient substitute for truffles, to provide flavouring, or to enhance the flavour and aroma of truffles in cooking. Some products called "truffle oils" contain no truffles or include pieces of inexpensive, unprised truffle varietals, which have no culinary value, simply for show. The vast majority is oil that has been artificially flavoured using a synthetic agent such as 2,4-dithiapentane. The scientific name is included on the ingredient list of truffle oils infused with natural truffles.

Vodka

Because more aromatic molecules in truffles are soluble in alcohol, they can carry a more complex and accurate truffle flavour than oil without synthetic flavourings. Many commercial producers use 2,4-dithiapentane regardless, as it has become the dominant flavour most consumers, unexposed to fresh truffles but familiar with oils, associate with them. Because most Western nations do not have ingredient labelling requirements for spirits, consumers often do not know if artificial flavourings have been used. It is used as a spirit in its own right, a cocktail mix or a food flavouring.

References

Additional resources

* * * *

External links

Website of the North American Truffling Society

Website of the Australian Truffle Growers
{{DEFAULTSORT:Truffle (Fungus) Edible fungi French cuisine Fungi in cultivation Italian cuisine Mushroom types Fungus common names