Melanosporum Research Articles

Influence of annual climatic variations, climate changes, and sociological factors on the production of the Périgord black truffle (Tuber melanosporum Vittad.) from 1903-1904 to 1988-1989 in the Vaucluse (France).

From 1903-1904 to 1988-1989, the two World Wars and sociological factors as rural desertification and changes in land uses mainly explained the decline of black truffle production in the Vaucluse department, which well reflects that of the whole of France. These can be correlated with the annual climatic variations as well as, from 1924-1925 to 1948-1949, the raw production rates of the managed truffle orchard of Pernes-les-Fontaines located in Vaucluse. The two methods used (correlation coefficients and Bayesian functional linear regression with Sparse Step functions) gave consistent results: the main factor explaining the annual variations of truffle production was the summer climatic water deficit of the year n. A general model including the rural exodus and the cumulated climatic water deficit of summer months both allowed to well explain the evolution of truffle production from 1903-1904 to 1988-1989 in the Vaucluse and its huge decrease. During that period, global warming had little effect. However, in the twenty-first century, all the scenarios predict increased summer water stress for the Mediterranean region, which could greatly affect black truffle production.

Identification of Soils Factors Influence in the Distributions of Tuber aestivum in Transylvanian Subcarpathian Hill, Romania

Truffles are one of the most hunted varieties of mushrooms in Europe due to their high price and their increasingly frequent use in the kitchen. As demonstrated by several studies, soil conditions are among the main factors that influence the spread and development of the black truffle species. The purpose of this study was to identify the soil factors which directly and indirectly influence the distribution of black truffles (Tuber aestivum Vittad.) in Romania and to identify the areas from the Subcarpathian Hills of Transylvania which are highly favourable to their existence and growth, using G.I.S. spatial analysis and databases which include soil characteristics (soil type, texture, gleization, stagno-gleization) and territorial localisation through GPS points indicating the samples of Tuber aestivum. By implementing the statistical model of spatial analysis (BSA – Bivariate Statistical Analysis) for each characteristic, a series of areas were classified into three classes of favourability (low, medium, high) for the growth of Tuber aestivum. The results were validated indirectly by comparing the overlapping of the areas from the high favourability class with the areas covered with tree species from the Quercus genus and directly, through field research (on the surfaces with maximum favourability), done by specialised truffle seekers. The results were validated with a very high confidence rate for both methods (method 1 - overlapping of approximatively 93%, method 2 - Tuber aestivum was identified on 12 out of 15 test surfaces from the high favourability class).

A risk assessment of Europe's black truffle sector under predicted climate change

The black truffle (Tuber melanosporum) is a highly revered culinary icon species that grows symbiotically with its host trees across several parts of southern Europe. Where harvested under natural or cultivated conditions, truffles can have a significant socioeconomic impact and may even form a key component of cultural identity. Although some aspects of truffle biology and ecology have been elucidated recently, the role of abiotic, environmental and climatic factors in the production and maturation of their fruitbodies is still largely unknown. Based on 36-year-long, continuous records of Mediterranean truffle yield, we demonstrate that decreased summer precipitation together with increased summer temperatures significantly reduce the fungus' subsequent winter harvest. Using state-of-the-art climate model projections, we predict that a significant decline of 78–100% in southern European truffle production is likely to occur between 2071 and 2100. The additional threats of forecasted heatwaves, forest fires, pest and disease outbreaks are discussed along with socioeconomic and ecological consequences of a warmer and dryer future climate. Our results emphasize the need for unravelling the direct and indirect effects of climate change on Europe's truffle sector and underline the importance of conservation initiatives at local to international scales.

Pezizomycetes genomes reveal the molecular basis of ectomycorrhizal truffle lifestyle

Tuberaceae is one of the most diverse lineages of symbiotic truffle-forming fungi. To understand the molecular underpinning of the ectomycorrhizal truffle lifestyle, we compared the genomes of Piedmont white truffle (Tuber magnatum), Périgord black truffle (Tuber melanosporum), Burgundy truffle (Tuber aestivum), pig truffle (Choiromyces venosus) and desert truffle (Terfezia boudieri) to saprotrophic Pezizomycetes. Reconstructed gene duplication/loss histories along a time-calibrated phylogeny of Ascomycetes revealed that Tuberaceae-specific traits may be related to a higher gene diversification rate. Genomic features in Tuber species appear to be very similar, with high transposon content, few genes coding lignocellulose-degrading enzymes, a substantial set of lineage-specific fruiting-body-upregulated genes and high expression of genes involved in volatile organic compound metabolism. Developmental and metabolic pathways expressed in ectomycorrhizae and fruiting bodies of T. magnatum and T. melanosporum are unexpectedly very similar, owing to the fact that they diverged ~100 Ma. Volatile organic compounds from pungent truffle odours are not the products of Tuber-specific gene innovations, but rely on the differential expression of an existing gene repertoire. These genomic resources will help to address fundamental questions in the evolution of the truffle lifestyle and the ecology of fungi that have been praised as food delicacies for centuries.

Black Truffle Aqueous Extract Attenuates Oxidative Stress and Inflammation in STZ-Induced Hyperglycemic Rats via Nrf2 and NF-κB Pathways.

Background and Purpose: Tuber melanosporum (black truffle) has been considered as a medicinal mushroom for a long time. T. melanosporum has the ability to attenuate oxidative stress and in turn diabetes mellitus (DM). DM has become an awfully common chronic unwellness, threatening people’s well-being. There are nearly 1 in 10 people in the world affected by diabetes. Oxidative stress plays a crucial role in vascular complications related to DM. Our study aimed to attain an effective treatment method to alleviate oxidative stress by scavenging free radicals and reducing inflammation, to display how truffle aqueous extract (TE) attenuates hyperglycemia.Methods: Streptozotocin (STZ)-induced hyperglycemic rat model was accustomed to check the hypoglycemic effect of black truffle by relating it with Nrf2 and NF-κB pathways. Varied biomarkers and inflammatory markers were analyzed.Results: Rats treated with TE showed reduced glucose levels, attenuated oxidative stress through regulation of SOD, CAT, VIT-E, and VIT-C. The gene expression of Nrf2 and NF-κB in rats treated with TE was increased to normal group level. The mRNA expression of inflammatory pathway genes and oxidative stress pathway genes in rats treated with TE was brought back normal. Similar results were achieved in the rats treated with standard drug, glibenclamide (GB). TE conjointly inhibits the state of inflammation within the tissues generally littered with the symptoms of hyperglycemia.Conclusion: The results of our study show the hypoglycemic impact of black truffle on STZ-induced hyperglycemia in rats via Nrf2 and NF-κB pathways, and both pathways have significant improvement that may support the hypoglycemic impact of truffle.

The mysterious parentage of the coveted black truffle

In the winter of 2016, ecologist Laure Schneider-Maunoury went truffle hunting in France. But she wasn’t looking to add the fungus to a culinary delicacy. Schneider-Maunoury, a graduate student at the National Museum of Natural History in Paris, was on the hunt for the truffle’s missing father, the form that contributes genes to generate the aromatic, edible fruiting body. Researchers still don’t know where these paternal truffles live or how the maternal and paternal partners find each other. Scientists are on the hunt for the paternal partner that sires the spores within the edible fruiting body of the black truffle. Image courtesy of Shutterstock/Vitalina Rybakova. It’s a mystery with major implications for farmers, chefs, and foodies enamored with the pungent, expensive black truffle ( Tuber melanosporum ). Slivers of the fungus, which can run hundreds of dollars per pound, grace dishes from risottos to pizzas. Although farmers can raise truffles in orchards of oak or hazelnut, where the fungus joins with the tree roots, the crop remains what some call “protodomesticated” because growers can’t control its reproduction. Complicating matters, yields from truffle grounds have plummeted in the past century, likely a result of dwindling habitat. “For most truffle growers, it’s a game—you never know if you’re going to get something out,” says Aurelie Deveau, a researcher in the field of ecogenomics who studies truffles at the French National Institute for Agricultural Research (INRA) in Champenoux, France. If researchers could work out the reproductive cycle, it might suggest more effective farming practices. The mystery and the potential ramifications have led researchers such as Schneider-Maunoury and her advisor, mycological ecologist Marc-Andre Selosse of the Paris museum, to go looking for the truffle father. Their recent work follows a decade of investigations into T. melanosporum reproduction. The part of the truffle people eat is the …

Ectomycorrhizae formed by three Japanese truffle species (Tuber japonicum, T. longispinosum, and T. himalayense) on indigenous oak and pine species.

Modern truffle cultivation systems started in Europe in the early 1970s and are now successfully used for several European truffles throughout the world. However, systems for indigenous novel truffle species need to be developed in several regions, especially where truffle cultivation has not been attempted so far, such as in Japan. Recently, two new and one known truffle species that are expected to be edible were reported from Japan: Tuber japonicum, T. longispinosum, and T. himalayense. Here, we conducted mycorrhization trials between these three truffle species and four native tree species in Japan (Quercus acutissima, Q. phillyraeoides, Q. serrata, and Pinus densiflora) using spore suspension and trap-plant seedling techniques under axenic pot culture conditions to understand their potential host ranges and mycorrhizal morphologies and to determine whether these inoculation methods are applicable for mycorrhization of Japanese truffles with native host plants. Of the 12 combinations, nine were successful for mycorrhization, including both oak and pine trees. The T. japonicum mycorrhiza was characterized by short, needle-shaped cystidia without septa, whereas the two black truffles, T. longispinosum and T. himalayense, were indistinguishable from each other because they shared the same morphological and anatomical characters such as brownish, long cystidia with right angle ramification. These features were similar to related black truffle species. The results of the present study indicate that the inoculation method used for European truffles can also be applied for mycorrhization between Japanese truffle species and compatible native pine and/or oak hosts in Japan.

Chinese black truffles: Tuber yigongense sp. nov., taxonomic reassessment of T. indicum s.l., and re-examination of the T. sinense isotype

A new species, Tuber yigongense, is described. ITS sequences derived from Chinese black truffles grouped into three clusters, each recognised as a different species: T. sinense, T. formosanum, and T. yigongense. Tuber sinense and T. formosanum cannot be separated morphologically, but T. yigongense differs from them by its yellow brown ascospores. Based on ITS sequence analysis, numerous Chinese specimens previously identified as T. indicum and T. himalayense are redetermined as either T. sinense or T. formosanum; although the phylogenetic results suggest that the two Indian species do not occur in China, the true taxonomic affinities cannot be fully resolved because of the lack of Indian sequences of T. indicum and T. himalayense.

Using mating-type loci to improve taxonomy of the Tuber indicum complex, and discovery of a new species, T. longispinosum.

Black truffles that morphologically resemble Tuber indicum have been known to occur in Japan since 1979. Our previous studies showed that there are two phylotypes of these truffles, both of which fell into the T. indicum complex (hereinafter “Tuber sp. 6” and “Tuber sp. 7”). However, their taxonomic treatment is still unclear. In this study, we conducted morphological and phylogenetic analyses for a total of 52 specimens from Japan (16 Tuber sp. 6 and 13 Tuber sp. 7), China (10 T. himalayense and 8 T. indicum), and Taiwan (5 T. formosanum). We compared ascospore ornamentation, size, distribution of asci with average number of spores per ascus, spine size and shape of the Japanese specimens with their allied taxa. For phylogenetic analysis, we sequenced two mating loci (MAT1-1-1 and MAT1-2-1) and three commonly used loci (ITS, β-tubulin, and TEF1-α). Three distinct lineages were recognized by phylogenetic analyses based on the sequences of the two mating-related loci and three independent loci. The Tuber sp. 6 sequences clustered with those of T. himalayense and T. formosanum, and there was no clear difference in morphology among them. Tuber sp. 7 formed a distinct lineage in each phylogram. The specimens tended to have five-spored asci more frequently than other allied species and could be characterized as having ascospore ornamentation with longer spines and narrower spine bases. We therefore described Tuber sp. 7 as a new species (T. longispinosum), and treat Tuber sp. 6 and T. formosanum as synonyms of T. himalayense.

Effect of lyophilisation in the black truffle (Tuber melanosporum) aroma: a comparison with other long-term preservation treatments (freezing and sterilization)

Effect of lyophilisation in the black truffle (<i>Tuber melanosporum</i>) aroma: a comparison with other long-term preservation treatments (freezing and sterilization)

The genomic tool-kit of the truffle Tuber melanosporum programmed cell death

A survey of the truffle Tuber melanosporum genome has shown the presence of 67 programmed cell death (PCD)-related genes. The 67 genes are all expressed during fruit body (FB) development of T. melanosporum development; their expression has been detected by DNA microarrays and qPCR. A set of 14 PCD-related genes have been chosen, those with the highest identities to the homologs of other species, for a deeper investigation. That PCD occurs during T. melanosporum development has been demonstrated by the TUNEL reaction and transmission electron microscopy. The findings of this work, in addition to the discovery of PCD-related genes in the T. melanosporum genome and their expression during the differentiation and development of the FB, would suggest that one of the PCD subroutines, maybe autophagy, is involved in the FB ripening, i.e., sporogenesis.

The anti-fatigue activities of Tuber melanosporum in a mouse model.

Tuber melanosporum (TM) is an edible fungus that exhibits antioxidant and anti-tumor activity via its unique bioactive metabolites. The present study analyzed the anti-fatigue effects of TM using a BALB/c mouse model. The anti-fatigue properties of TM were evaluated by assessing the endurance of mice by performing forced swimming, rotary rod and running tests. Following 2 weeks TM treatment, hepatic and muscular ATP, and glycogen levels were increased in mice subjected to 30 min swimming, compared with controls. Similarly, levels of serum lactic acid and lactic dehydrogenase were decreased in the same group, compared with the control. Additionally, TM treatment reduced reactive oxygen species and malondialdehyde levels, and increased superoxide dismutase and glutathione peroxidase levels in the muscle, liver and/or serum. The effect of TM on hormone levels was also investigated in the present study, as different efficacies of TM were observed in male and female mice. TM treatment increased serum levels of progesterone, estradiol and testosterone in female and male mice, whereas a decrease in serum luteinizing hormone levels was only observed in females. A decrease in serum follicle-stimulating hormone levels was identified in females, whereas an increase was observed in males. The current study demonstrated that the anti-fatigue effects of TM occur via the regulation of oxidative stress, energy metabolism and hormone levels.

Characterization of an innovative device controlling gaseous exchange in packages for food products

The work describes both the characterization carried out and the experimental results from an innovative device allowing the gas exchange across a sealed package. The device is especially suitable for fresh fruit and vegetable preservation during cold storage, as it allows for the management of the headspace atmosphere inside sealed packages containing food products presenting metabolic activity.Characterization results confirm the device's suitability for managing the bidirectional gas flow. For each tested device, the hydro-dynamical parameter and the diffusion parameter have been measured to define its steady-state behaviour. The steady-state gas concentrations reached in the package show the aptness of the devices for use with specific products; these equilibrium gas concentrations depend on the device type and on the mass of product contained in the package.The results of simulated storage demonstrate that some products (pomegranate arils and table grapes) require preconditioning of the package free volume to reach the optimal gas concentrations in a short time. Other products (black truffle) with very high metabolic activity could reach the optimal condition without package preconditioning depending on the free volume.

The Antidiabetic and Antinephritic Activities of Tuber melanosporum via Modulation of Nrf2‐Mediated Oxidative Stress in the db/db Mouse

Tuber melanosporum (TM), a valuable edible fungus, contains 19 types of fatty acid, 17 types of amino acid, 6 vitamins, and 7 minerals. The antidiabetic and antinephritic effects of TM and the underlying mechanisms related to oxidative stress were investigated in db/db mice. Eight-week oral administration of metformin (Met) at 0.1 g/kg and TM at doses of 0.2 and 0.4 g/kg decreased body weight, plasma glucose, serum levels of glycated hemoglobin, triglyceride, and total cholesterol and increased serum levels of high-density lipoprotein cholesterol in the mice, suggesting hypoglycemic and hypolipidemic effects. TM promoted glucose metabolism by increasing the levels of pyruvate kinase and hepatic glycogen. It also regulated the levels of inflammatory factors and oxidative enzymes in serum and/or the kidneys of the mice. Additionally, TM increased the expression of nuclear respiratory factor 2 (Nrf2), catalase, heme oxygenase 1, heme oxygenase 2, and manganese superoxide dismutase 2 and decreased the expression of protein kinase C alpha, phosphor-janus kinase 2, phosphor-signal transducer and activator of transcription 3, and phosphor-nuclear factor-κB in the kidneys. The results of this study reveal the antidiabetic and antidiabetic nephritic properties of TM via modulating oxidative stress and inflammation-related cytokines through improving the Nrf2 signaling pathway.

Retracted: Antioxidant Activity and Characterization of One New Polysaccharide Obtained from Perigord Truffle (Tuber huidongense).

[This retracts the article DOI: 10.1155/2016/3537193.].

Identification of volatile flavour components of Tuber melanosporum using simultaneous distillation-extraction

Black truffles are famous for their unique flavours. Headspace solid-phase microextraction and the electronic nose have been used to analyse their flavours in some investigations. In a previous work, the volatile flavour compounds in black truffles harvested in China were extracted using simultaneous distillation-extraction (SDE) and analysed using gas chromatography-mass spectrometry (GC-MS). Extraction conditions were optimised in that previous study and are now applied in the present work. The temperature of the solvent flask was maintained at 70°C using a water bath and the samples were placed in boiling water; extraction time was 3 hours. Fifty-seven volatile flavour compounds were tentatively identified, including seven alcohols, two acids, six esters, 12 aldehydes, 14 ketones, two phenols, six pyrazines, six sulphur compounds and three other components. Aldehydes and ketones were present at the highest levels.

ECOLOGICAL AND GENETIC ADVANCES IN THE CULTIVATION OF TUBER SPP.

Recent advances on the ecology and genetics of true truffles (Tuber spp.) are reported and their impact on truffle cultivation is discussed. New insights have been gained on truffle soil ecology and interrelationships of truffles with associated microorganisms in the soil. For instance, some bacteria seem to play a key role in truffle fruiting body formation and maturation. However, the most important advance in truffle genetics over the past 20 years has been the sequencing of the Tuber melanosporum genome and the discovery that truffles, like other Pezizalean fungi, are heterothallic. This finding has had a significant impact on research on truffles and many studies have been devoted to better understanding the distribution of the mating types in soil in natural and cultivated truffières. The characterization of the mating type idiomorphs of several Tuber species has led to the possibility of selecting mycelial strains for truffle cultivation in particular sites.

Black Truffle Harvesting in Spanish Forests: Trends, Current Policies and Practices, and Implications on its Sustainability.

The European black truffle is a mycorrhizal fungus native to Spanish Mediterranean forests. In most Spanish regions it was originally commercially harvested in the second half of the 20th century. Experts agree that wild truffle yields suffered a sharp decline during the 1970s and 1980s. However, official statistics for Spanish harvest are scarce and seemingly conflicting, and little attention has been paid to the regime for the exploitation of truffle-producing forests and its implications on the sustainability of this resource. Trends in harvest from 1969 to 2013 and current harvesting practices were analyzed as a case study, taking into account that Spain is a major truffle producer worldwide, but at the same time truffles have only recently been exploited. The available statistical sources, which include an increasing proportion of cultivated truffles since the mid-1990s, were explored, with estimates from Truffle Harvesters Federation showing higher consistency. Statistical sources were then compared with proxies for wild harvest (rents from truffle leases in public forests) to corroborate time trends in wild harvesting. Results suggest that black truffle production is recovering in recent years thanks to plantations, whereas wild harvest is still declining. The implications of Spanish legal and institutional framework on sustainability of wild truffle use are reviewed. In the current scenario, the decline of wild harvest is likely to continue and eventually make commercial harvesting economically unattractive, thus aggravating sustainability issues. Strengthening of property rights, rationalization of harvesting pressure, forest planning and involvement of public stakeholders are proposed as corrective measures.

Antimicrobial activity of gallic acid against food-related Pseudomonas strains and its use as biocontrol tool to improve the shelf life of fresh black truffles

Refrigeration alone or in combination with other technologies represents the main tool used in the last decades to preserve the freshness of black truffles. This is principally due to the delicateness and vulnerability of this edible hypogeous fungus, so that other invasive preservation practices cannot be adopted. However, the proliferation of some microbial species during the cold storage still represents an unsolved problem. Pseudomonads are among the main spoiler bacteria responsible for the deterioration of refrigerated black truffles. Their growth ability at low temperatures requires the use of additional hurdles to prolong the shelf-life of truffles without altering their major features. The use of natural compounds may represent an alternative system for the biocontrol of this kind of product. Specifically, gallic acid (GA) is a phenolic acid naturally present in different foods, whose effectiveness was in vitro demonstrated against Pseudomonas spp. In our study, we reported the antimicrobial activity expressed by GA not only in vitro, using as target bacteria Pseudomonas putida DSMZ 291T, P. fluorescens DSMZ 50090T, P. fragi DSMZ 3456T and Pseudomonas spp. P30-4, previously isolated from black truffles, but also in situ on fresh black truffles stored at 4°C for 28days. Our results showed Minimum Inhibitory Concentrations (MIC) of 2.5mg/mL GA for all tested strains, except for P. fluorescens DSMZ 50090T, having a MIC corresponding to 5mg/mL GA. The Minimum Bactericidal Concentration (MBC) was 10mg/mL for all strains. The analysis of kinetic parameters showed that the survival declined passing from 2.5 to 10mg/mL GA concentrations, with P. fluorescens confirmed to be the most resistant strain. Moreover, images obtained from Scanning Electron Microscopy revealed that Pseudomonas cells were strongly injured by the treatment with GA at 2.5mg/mL concentration, displaying visible pores on the cellular surfaces, absence of flagella and lysis with loss of cytoplasmic material.The storage test performed on fresh black truffles confirmed in situ the GA antimicrobial activity observed in vitro, with a drastic reduction not only of Pseudomonas spp., but also of the other assessed microbial groups, including Enterobacteriaceae and Eumycetes. Finally, sensory analysis established the absence of off-flavours and the preservation of positive features in black truffles treated with 2.5mg/mL GA and stored for 28 d at 4°C. The results obtained in this study suggest that GA is a potential biocontrol tool to decontaminate and preserve fresh black truffles during refrigerated storage.

Is Tuber melanosporum colonizing the roots of herbaceous, non-ectomycorrhizal plants?

Abstract The ectomycorrhizal Tuber melanosporum forms edible fruit-bodies after mating between two haploid parents: a maternal individual, which feeds the fruit-body and colonizes surrounding ectomycorrhizas, and a paternal one hitherto undetected around fruit-bodies. Several other aspects of T. melanosporum ecology remain unclear, such as the formation of a brule around the mycelium, i.e. patches where plant growth is impaired. Here, we test the hypothesis that T. melanosporum, and specifically paternal individuals, is present on the roots of herbaceous, non-ectomycorrhizal plants of the brule. Specific primers detected T. melanosporum on 78.9% of the plant individuals investigated (89.7% of the 80 species considered), and metabarcoding confirmed its presence on 46 of the 70 plant individuals investigated. Genotyping with 13 microsatellites detected maternal individuals of nearby fruit-bodies, but not paternal individuals, whose niche thus remains elusive. We discuss the possibility that T. melanosporum is also a root endophyte in non-ectomycorrhizal plants.