Black truffle cultivation : a global reality

Aim of study: In recent decades the cultivation of the black truffle Tuber melanosporum has expanded across all the Mediterranean-climate regions, but also to other regions outside the European standard for the species. We aim to describe the current extent of T. melanosporum cultivation. Area of study: Tuber melanosporum plantations in Europe, the Mediterranean basin, Australia, New Zealand, China, America and South Africa. Material and methods: The socioeconomic impact of T. melanosporum cultivation, the way in which the current situation has been achieved and the knowledge needed for its progress are reviewed. Research highlights: T. melanosporum has been successfully cultivated in several countries outside its natural area, but many practices are still empirical and thus yields cannot be guaranteed. The recent advances in molecular techniques and genome science are helping to overcome some of the difficulties traditionally constraining truffle research. The role of truffles as a transitional element between agricultural and forestry activities makes its cultivation a paradigm of sustainable rural development.


Introduction
Wild edible fungi have traditionally been used as food or medicine worldwide (Boa, 2004).Some of them -mostly saprotrophic-are cultivated (e.g.Agaricus bisporus), while many others are exclusively harvested in forests.Truffles are one of the few cultivated mycorrhizal fungi: they make part of the rural European culture, and nowadays they are widely used in international haute cuisine.
The term "truffle" is sometimes used to name all hypogeous mushrooms in general, but it specifically refers to the genus Tuber.Bonito et al. (2010) report at least 180 species of Tuber around the world, although only about 13 have commercial interest (Bonito et al., 2009).The quintessential truffles are the European black truffle (Tuber melanosporum Vittad.) and the Italian white truffle (Tuber magnatum Pico).
T. melanosporum was f irst cultivated in France during the 19 th century (Olivier et al., 1996) and it is currently cultivated worldwide (mainly in regions with Mediterranean-like climate).Despite research efforts cultivation is not completely domesticated.More recently, other Tuber species have also been successfully cultivated, such as Tuber aestivum Vittad.and its form uncinatum, Tuber borchii Vittad.and the Tuber indicum complex (Wang et al., 2006) (Chevalier and Frochot, 1997;Zambonelli et al., 2000;Hu et al., 2005), whereas the attempts to grow the native North American Tuber species are in their first stages (Lefevre, 2012).Much effort has been devoted to T. magnatum, although without success (Gregori, 2007;Bencivenga et al., 2009).
This review focuses on the current extent of T. melanosporum cultivation, which is by far the most widespread.We describe its potential socioeconomic impact, the way in which the current situation has been achieved and finally the knowledge needed for its progress.three countries, truffles are harvested not only in planted truffle orchards (cultivated truffles) but also in natural forests (wild truffles).The value of the T. melanosporum production is estimated to be around 20 million euro per year in France (Escafre and Roussel, 2006), 7.5 million euro in Spain (estimated for the past decade on the basis of the mean prices at Vic market, in north-eastern Spain), and 4 million euro in Australia in 2012 (Duell, 2012).In Italy the production value of all species of Tuber together was estimated to be 18 million euro in 1999 (Pettenella et al., 2004).
The price that farmers receive for T. melanosporum in Europe ranged in the past decade from less than 150 to more than 800 euros kg -1 .The price for retail customers can be much higher: e.g. in Paris and London prices higher than 2000-4000 euros kg -1 can be achieved.This fact has encouraged truffle growers to sell directly to restaurants and to use retail e-commerce.In Australia the mean price in 2012 for the higher quality class was about 950 euros kg -1 (Duell, 2012).
The high price of T. melanosporum makes its cultivation an interesting enterprise for farmers wherever suitable environmental conditions exist.A review of economic evaluations of truffle plantation in Europe by Bonet and Colinas (2001) showed that the internal rate of return (i.e. the interest yield expected from the investment) was always above 9%, although the return time of the investment was longer than 10 years.The GET (2002) estimated that markets would be able to absorb around 1,000 t of T. melanosporum, which represents more than ten times the current production.In Spain its current discounted value has increased at an annual rate of 3% over the past 50 years (Reyna, 2007b).
The total economic impact includes not only fresh truffles sold by farmers, but also agritourism, local mycological gastronomy, production of value-added truffle products, truffle fairs and retail markets, increase in agricultural land price in truffle-growing regions, production of mycorrhizal seedlings in nurseries, dog training, consumption of agricultural supplies by truffle growers, technical assessment services, etc.The total economic impact of T. melanosporum was estimated to be around 70 million euros per year in France (Escafre and Roussel, 2006).In Italy, the total economic impact of all Tuber species together was estimated to be more than 100 million euros (Gregori, 2013).

Social value: rural development
In many T. melanosporum-producing regions of the Mediterranean basin the environmental conditions and the small size of plots limit the yield of traditional agricultural crops (Pinto-Correia, 1993).Truffle cultivation represents an alternative for their agriculture: an economic diversification and an extra income.When nonagricultural activities are brought into play (e.g.agritourism) truffle fulf ils a more robust role in rural development.Besides, maintaining marginal agricultural lands cultivated helps to preserve the traditional Mediterranean agroforestry landscapes and rural population.
The harvesting of wild T. melanosporum also plays a role in the rural economy of Italy and Spain.The value that truffles add to forests is particularly interesting in Mediterranean forests: given their low productivity (Domínguez-Torres and Plana, 2002) it could promote involvement of the rural communities in forest protection and management.
In Italy and France truffles are a part of the rural cultural heritage and a reason for pride.Truffle has encouraged the development of partnerships and associations of growers, municipalities (such as the Italian Città del Tartufo) and gourmets.Ecomuseums such as those in Sorges (France), San Giovanni d'Asso (Italy) and Metauten (Spain) introduce the public to the various aspects of truffles.

Environmental value
In its natural area, T. melanosporum can be grown with low environmental impact: the use of machinery and chemicals is limited, so it can be easily considered organic farming.Soil tilling of these plots increases water infiltration rates.The maintenance of soil conservation structures limits soil erosion risk in steep slopes.The use of native Quercus as host plants contributes to the conservation of natural forests.In the fireprone Mediterranean landscapes, T. melanosporum plantations constitute excellent firebreaks due to low plantation densities, soil tilling and the herbicidal effect of the fungus.

The history of truffle cultivation
Hypogeous fungi (most probably desert truffles of the genera Terfezia and Tirmania) were consumed in the Antiquity by Mesopotamics, Egyptians, Greeks and Romans.During the Middle Ages they are scarcely cited in Europe, but in the Renaissance truffles gained a reputation in Italy and France, and truffle consumption spread among wealthy people (Reyna, 2007a).Manna (2005) reports harvest regulations in Italy during this period.Ceccarelli wrote a monograph on the management of wild truffières in 1564 (Granetti, 2005).
During the 18th and 19th centuries the consumption of truffles increased thanks to gourmets such as Brillat-Savarin.This encouraged the spreading of truffle harvesting and the management of wild truffières.A major advance occurred in the early 19th century when the French farmer Joseph Talon had the idea of sowing acorns from truffle-producing trees near or inside the truffières.Auguste Rousseau disseminated the technique and thousands of hectares of oaks were planted thanks to this idea, boosted by the French reforestation laws of 1860 and 1882 (Diette and Lauriac, 2005) and the expansion of available agricultural land due to the widespread vineyard destruction by the Phylloxera plague (Olivier et al., 1996).This resulted in the golden age for truffle production, with estimated productions of 1,588 t in 1868, and 2,000 t in 1892.In Italy, Mattirolo and Francolini also promoted reforestations to increase truffle production (Granetti, 2005).In those decades De Bosredon, Chatin and Pradel wrote monographs on truffle ecology and cultivation.During the same period Carlo Vittadini provided the first detailed morphological descriptions of many Tuber sporocarps and a classification system (Trappe et al., 2009).
In the 20th century French production sharply declined to the current 10-60 t per year, due to the rural depopulation caused by the two World Wars and by the rural to urban drift.The forest stand density increased and much of farmers' empirical knowledge was lost (Olivier et al., 1996).In Italy the decline was not so severe and it is limited to the first half of the century (Manna, 1990).In the late 1960s the progress in truffle cultivation seemed arrested despite the works of Rebière and Mannozzi-Torini.
A breakthrough occurred in the early 1970s, when researchers from the IPLA and the INRA developed the inoculation of seedlings with Tuber in the nursery (Chevalier, 2001).Almost 90 years before, Frank had coined the term mycorrhiza and postulated that this structure involved a symbiotic relationship (Trappe et al., 2009).T. melanosporum-inoculated seedlings were released to the market in France in 1973 (Chevalier, 2001), greatly increasing plantation activity.On the other hand, in Italy it gained momentum from 1982 (Bencivenga, 2001).
At that time French truffle growers had already began to associate, and the government had established public aids for plantation establishment (Olivier et al., 1996).Italy organised the first International Truffle Congress in 1968.Up to the 1980s the intensive cultivation techniques (Pallier method) were dominant in plantations, whereas from the 1990s more extensive models (Tanguy method) were proposed (Olivier et al., 1996).
Spain only became involved in the international truffle market in the 1960s, when wild truffières across the country began to be systematically searched and exploited.An alarming decrease in production was observed from the 1980s, after 20-30 years of intensive harvesting in a context of rural depopulation and increasing forest stand density.Except for the Arotz estate (around 600 ha planted in the 1970s), the plantation of mycorrhizal seedlings was minimal until the 1990s.In that decade truffle growers began to associate, and regional governments established public assistance for the establishment of plantations.

Current state in France, Italy and Spain
The annual European production of T. melanosporum was an average of around 58 t for the period 2003-2012, although highly variable from year to year (Table 1, Fig. 1).
In France, the production seems steady since the 1990s (Fig. 1), despite the rate of plantation (Table 1).Our estimation of mean yield in mature plantations is very low (Table 1), but it is consistent with the 0.5-3 kg ha -1 year -1 cited by Escafre and Roussel (2006).
French growers benefit from a high domestic demand (it consumes most of the French and Spanish production), the support from public agencies to plantation establishment (Sourzat, 2007), and an extensive network of scientists and specialists (although much of their work is not published in scientific journals) (Table 1).The experience of experimental stations in which researchers and growers closely collaborate, such as that of Le Montat (Lot), seems especially interesting.
In Italy, we estimate that the mean yield of mature plantations is similar to that of France (Table 1).The strengths of T. melanosporum cultivation are also similar, with a greater emphasis on exportation (Galluzzo, 2013).The introduction of exotic species such as T. indicum s.l. and Tuber sinoaestivum Zhang et Liu (Zhang et al., 2012) in Italian orchards may become a serious problem (Murat et al., 2008;Zambonelli et al., 2012).
In Spain, plantations have made up for the collapse of wild production over the past few decades (Fig. 1).The mean yield of mature plantations is somewhat higher than in France and Italy (Table 1), despite the fact that the mean age of plantations is lower (plantation establishment started later).In the Arotz planta-tion the yield in the late 1990s was lower than 2 kg ha -1 year -1 in non-irrigated areas, and up to 45 kg ha -1 year -1 in the irrigated areas (Carbajo, 1999).Domestic consumption of truffles in Spain is less than 10%, and promotion activities such as fairs are still limited (Table 1).In some regions the high plantation rates during the 2000s were mainly due to grants covering 100% of the cost of plantation establishment (excluding land purchase), thus making planting a business in itself.Some experts argue that a part of these plantations will not be carefully managed and will be less likely to succeed.

Cultivation outside the native range North America
The first T. melanosporum-inoculated plantations were established in 1979 in North Carolina and 1980 in California, and the first sporocarps were harvested in 1987 in northern California (Renowden, 2005;Lefevre, 2012).Nowadays there are plantations from California to southern British Columbia (Canada) and from central Texas to North Carolina (Renowden, 2005;Lefevre, 2012).Most of them were planted after 2003 (Pilz et al., 2009).Sporocarp production has been reported in California, North Carolina, Tennessee, Texas, Oregon and British Columbia (Lefevre, 2012;Berch, 2013).Soils are usually limed to raise the pH.C. avellana, Q. robur and Q. ilex are commonly used as host plants.
These plantations have usually spread without any coordinated initiative or technical assessment.Furthermore, in some cases the sites are far from the climatic requirements of T. melanosporum (Lefevre, 2012).The overall yields are far from optimum (Table 2).

Australia and New Zealand
New Zealand was the first country in the Southern Hemisphere to establish T. melanosporum plantations (in 1987) and to harvest sporocarps (in 1993).The initiative was led by a scientist (Ian Hall), supported by the government (Hall and Haslam, 2012).Its development was based on climatic and edaphic studies, production of mycorrhizal seedlings in the country and quality control of mycorrhizal seedlings.A variety of field essays were established to determine the best management practices (Guerin-Laguette et al., 2009).However, most information remains unpublished due to confidentiality (Hall and Haslam, 2012).C. avellana and Q. robur were initially used as host plants, and Q. ilex was introduced later (Zambonelli et al., 2009).
Australia began to plant some years later and benefited from New Zealand experience, important subsidies for plantation establishment and a more continued government support for research (Hall and Haslam, 2012), thus being reflected in the planted surface (Table 2).Plantations are currently common in Western Australia (notably around Manjimup and Pemberton), Tasmania, New South Wales and Victoria (Lee, 2008).The agricultural practices have been adapted to the environmental conditions: they are more intensive than in Europe and plantation densities are higher (Zambonelli et al., 2009).
The productive results in both countries are contrasting (Fig. 2): we estimate that the mean yield of mature plantations is 0.5 kg ha -1 year -1 for New Zealand and 9.2 kg ha -1 year -1 for Australia.The latter can Black truffle cultivation: a global reality 321 be considered an important success, although the differences in productivity among plots are high and most production comes from a limited number of plantations (Hall and Haslam, 2012).One important advantage for these countries is that forests are dominated by endomycorrhizal plants or ectomycorrhizal fungi very different from the European ones (Zambonelli et al., 2009).As calcareous soils are scarce, liming the soil is a common practice, like in North America, and rising of the pH can also reduce the competitiveness of the scarce ectomycorrhizal fungi (Lefevre and Hall, 2000).Australia and New Zealand produce in counter-season to the main producers and consumers, and this helps their exports given that the truffles are mostly consumed fresh.In addition, their domestic demand is rapidly increasing: truffle fairs are organised to spread its culinary use, and about 800 kg were consumed in Australia in 2012 (Duell, 2012), with the bulk exported.
The success of some plantations is threatened by the accidental introduction of T. brumale (through the imported sporocarps used as inoculum) in both countries (Linde and Selmes, 2012;Guerin-Laguette et al., 2013).

China
The first T. indicum s.l.plantation was established in Taiwan in 1989, and the first sporocarps were harvested in 1997 (Hu et al., 2005).In continental China, the first T. indicum s.l.sporocarps and the first T. melanosporum sporocarps were harvested in neighbouring plantations in Guizhou (Wang, 2012).Another T. melanosporum plantation was established in Hunan (Wang, 2012), despite the excessive summer temperatures and low winter temperatures (Hall, 2013).More T. indicum s.l.plantations have been established in recent years in Guizhou, Hunan, Sichuan and Yunnan using native Quercus, Pinus and Castanea as hosts (Wang, 2012).
In most cases these activities were supported by universities and implied the development of nursery techniques.However, quality control of seedlings is not common and many plantations are established on forest soils (Wang, 2012).Most truffles are exported and the domestic demand is low.Zambonelli et al. (2009), Hall and Haslam (2012), Henríquez (pers.comm.) and Miros (pers.comm.) 3 According to Treloar (2013); to the comparison of current surfaces to those 5-7 years ago (Ramírez et al. 2007;Lee 2008); and in the case of the USA to seedling production of the most important nurseries (Cocina et al. 2013) and common plantation densities. 4According to Cocina et al. (2013).plantations are still young and sparse, and in many cases the sites do not fulfil T. melanosporum climatic requirements.Some plantations have already produced sporocarps in Israel, Morocco and Sweden (Khabar 2007;Turgeman et al., 2012;Wedén et al., 2013).

Europe and the Mediterranean basin
The interest on T. aestivum/T.uncinatum cultivation is also recent and widespread.These plantations are more likely to succeed given the wider ecological requirements of this species (Stobbe et al., 2013).Israel is an illustrating example (Turgeman et al., 2012).In 1994 T. melanosporum-inoculated seedlings were planted, and in 1999 a sporocarp was harvested.But in 2002 it was impossible to find T. melanosporum mycorrhizas in the plantation.In 1999 more seedlings were planted, but T. aestivum-inoculated seedlings were non-intentionally introduced.In 2010 about 15 kg ha -1 of T. aestivum were harvested and it has continued to fruit.

South America and South Africa
Following New Zealand's example, the Universidad Católica del Maule started a project to cultivate T. melanosporum in Chile with government support (Fundación para la Innovación Agraria).The first plantation was established in 2003 and the f irst truffles were harvested in 2009 (Table 2).Most plantations are located between the regions of Valparaíso and Los Ríos.Soils are usually limed to raise pH.Q. robur, Q. ilex and C. avellana are the most used host plants (Henríquez, pers. comm., www.trufaschile.cl).
The initiative was based on a climatic and edaphic study of Chile, and the development of nursery techniques to produce mycorrhizal seedlings.More recently, the public initiative is addressed to establish field essays aimed at determining the best management practices and the environmental factors that enhance fruiting.Public efforts have been also launched to promote the association of growers, to train farmers and to develop commercial strategies.Being in the Southern Hemisphere, Chile has the opportunity to produce counter-season to Europe.In contrast, their domestic demand is still very low, and their farmers need technical assessment on quality of mycorrhizal seedlings and management practices.
In 2008 a nursery was established in Argentina and the first seedlings were planted in 2010 (Table 2).The f irst plantations are located in south Buenos Aires region and Río Negro (Henríquez, pers.comm.).People in neighbouring countries like Uruguay, Peru and Brazil have recently shown interest in starting truffle cultivation projects (Henríquez, pers. comm.).
In South Africa, T. melanosporum plantations were initiated in 2008 through a joint venture and the establishment of several nurseries (Table 2).Q. robur, C. avellana and Q. ilex are the most used host plants (Miros, pers.comm., http://woodfordtruffles.co.za/).

Basic research
The cultivation of T. melanosporum is not completely domesticated, as the uncertainties around the mating process remain (Selosse et al., 2013).Basic research on truffles has been constricted by the difficulties to observe their development: the symbiotic phase is microscopic and the growth of the mycelium in pure culture is slow, whereas the sporocarp grows underground and over a period of several months.
In recent years molecular techniques are allowing a great progress: they are used to identify sporocarps, mycorrhizas and mycelia; to recognise genetically identical individuals (genets); and to determine the molecular bases of truffle biology.The genome of T. melanosporum has been recently sequenced by the Tuber Genome Consortium, opening the possibilities of genomics to truffle research (Martin et al., 2010).These tools support novel approaches to important research gaps in the mechanisms regulating symbiosis, the trophic state of the fungus, population genetics and the mechanisms involved in fruiting.Linking gene functions and interactions with the biology and ecology of the fungus will improve the design and management of plantations.
An important breakthrough has been the confirmation that T. melanosporum is heterothallic (Riccioni et al., 2008), the identification of two mating types, and the characterisation of the genes involved (Rubini et al., 2011a).However, the sex organs are still largely unknown: only ascogonia have been rarely reported (Callot, 1999).Le Tacon et al. (2013) hypothesised that the ascogonium connects the mycorrhiza to the sporocarp during all its development.
The understanding of the ectomycorrhizal relation is being improved by recent studies on the signalling pathways to its establishment, the mechanisms of the fungus to inhibit the defensive response of the plant, the mechanisms of the partners to control each other, the role of nutrients transfer in the maintenance of the relation, the ability of the fungus to cleave sucrose Black truffle cultivation: a global reality (Plett and Martin, 2011) or the role of truffle volatiles in the first contact (Splivallo et al., 2011).
Although T. melanosporum retains some genes encoding enzymes responsible for degrading plant living cells, it has less degradative enzymes than saprotrophic fungi, thus indicating a lower ability to degrade organic tissues (Plett and Martin, 2011).This makes the fungus highly dependent on its host: Le Tacon et al. (2013) found that even in the late stages of the sporocarp development most carbon was supplied by the plant.The analysis of the transcription factors can help to understand the variations in the trophic behaviour of the fungus in each developmental stage (Montanini et al., 2011).
The methods for quantifying mycelium of T. melanosporum in the soil have allowed Liu et al. (2014) to monitor its spread and increase of density in young plantations.Suz et al. (2008) showed the relation between the abundance of mycelium and the formation of the brûlé.Liu et al. (2014) also hypothesised the existence of a mycelium-carrying capacity of the soil, and it would be interesting to understand the relation of this with the abundance of volatiles.Murat et al. (2013) found that T. melanosporum genets in young plantations were mostly small (diameter lower than 1 m), and few of them were found from year to year.Rubini et al. (2011b) showed that in the nursery genets compete each other for root tips, leading to the exclusion of most genets in 18 monthold seedlings.In the field intraspecific competition causes a spatial separation between mating types that can affect fruiting potential (Rubini et al., 2011b).Selosse et al. (2013) hypothesised that the mating-type genes could also be controlling vegetative incompatibility, but Iotti et al. (2012) did not find genes related to mating-type heterokaryon incompatibility in T. melanosporum.
The understanding of the mechanisms triggering fruiting is being improved by the studies on the regulome involved in developmental shifts from the symbiotic to the reproductive phase, on carbon transfer from the plant to the sporocarp, and on mating types.But it is also essential to know which factors of the soil environment are involved: Pacioni et al. (2014) suggested that variations in soil temperature and water content in spring are key, and proposed to use ground penetrating radars to monitor the sporocarps without disturbing their environment.
The translation of basic research to agricultural practices can be obscured by the interaction between T. melanosporum and other soil organisms (e.g.fungal competitors, bacteria modulating the mycorrhizal relation, or interacting with the fruiting).Metagenomics makes the study of soil microbial communities easier.

Cultivation challenges
Nowadays many of the practices in T. melanosporum cultivation are still empirical.The success of plantations cannot be guaranteed: plantations largely differ in the sporocarp yield, the percentage of productive trees and the age at which they start producing (productive onsets at age 4 and later than year 15 have been reported).
The quality of some nursery seedlings is a problem in countries without mandatory certification systems.It can be the cause of failure for some plantations and the way that exotic species are introduced.The production of seedlings with known mating types is a challenge for the future, since they are currently inoculated with spores (Rubini et al., 2011b).
The experience in North America and the Southern Hemisphere proved that it is possible to grow truffles in naturally acidic soils after liming.But if not enough lime is added to stabilise the pH, it decreases in a few years, making periodic liming necessary.Sourzat (2008Sourzat ( , 2010) ) drew attention to other soilrelated issues jeopardising the success of plantations in France: the chemicals applied in the previous land use and the high pressure of ectomycorrhizal competitors (particularly T. brumale and T. aestivum) in landscapes dominated by forest patches.The competition of soil-borne fungi points to the need to understand better the factors determining the structure of ectomycorrhizal communities and their dynamics, including the possible role of truffle volatiles (Splivallo et al., 2011).
In contrast, in Spain the plantations are usually located in extensive agricultural landscapes, so these problems are less frequent.However, temperatures are higher and rainfall is more scarce and irregular.This reduces the survival of the sporocarps during the summer, making research on irrigation and soil water conservation a priority.
Other challenges in French plantations (Sourzat, 2008(Sourzat, , 2010) ) are the short productive life of some young plantations and the high stand densities in mature plantations.The latter draws attention to the importance of pruning and thinning.Old plantations (planted before the 1970s) which are not producing currently are seen as an opportunity for spreading truffle production by forest management.
Large concentrations of plantations pose new threats: e.g. the truffle growers in Sarrión (Teruel) complain that in recent years the damages of insects on sporocarps are increasing, especially in dry and hot autumns.
Outside France and Italy most plantations are still young and management techniques are not adapted to the local conditions (soil water and temperature regimes, aeration, organic matter, host plants, soil-borne ectomycorrhizal community, etc.) yet.There is not a unique management system that works in all the environmental conditions suitable for T. melanosporum growth.Monitoring mycorrhizas and mycelium, tree growth and physiology, and soil microclimate in these plantations is highly recommendable.In this way, it could be assured that they remain potentially successful, and that management practices could be quickly improved.
A major problem in Australia is the abundance of sporocarps growing near the soil surface in irrigated plantations.These are more frequently damaged by pests, diseases, desiccation and frosts.The first studies on the matter point that reducing the irrigation and increasing the irrigation interval could help to decrease the damages (Eslick and Dell, 2013).
In countries with a meaningful wild production (Spain and Italy) the conservation of this production is an important concern: this involves sustainable harvesting and habitat improvement (Garcia- Barreda and Reyna, 2013).
Finally, if climate change predictions for the Mediterranean basin (decrease in summer rainfall, increase of temperatures and increase in interannual variability of both rainfall and temperature) are confirmed, the suitability of many native T. melanosporum areas for cultivation (specially the warmest ones) will be reduced (Colinas et al., 2007).A planning effort will be needed to assess the future suitability of the current native range and to adapt the cultural practices to the new situation.

Figure 1 .
Figure1.Estimates for T. melanosporum production from season 1990-1991 in France, Italy, Spain (according to the European Group for Truffles for the data up to2009-2010, and to Oliach, pers.comm.and Gregori pers.comm.for the recent ones) and Australia(Duell, 2012).

Figure 2 .
Figure 2. Estimation of current production of T. melanosporum.

Table 1 .
Main features of T. melanosporum production and associate activities in France, Italy and Spain

Table 2 .
Main features of T. melanosporum plantations outside its natural distribution area T. melanosporum cultivation is being essayed across Europe and the Mediterranean basin.However, these