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

Seasonal Succession of Fungal Communities in Native Truffle (Tuber indicum) Ecosystems

Truffles are a rare underground fungus and one of the most expensive, and sought-after kitchen ingredients in the world. Microbial ecology plays an important role in the annual growth cycle of truffles, but fungal communities in native truffle ecosystems are still largely unknown, especially for Tuber indicum from China. In this study, the spatial and temporal dynamics of soil physicochemical properties and fungal communities were described associated with four T. indicum-producing plots (TPPs) and one non-truffle-producing plot in four successive growing seasons. A total of 160 biological samples were collected, 80 of which were used for the determination of 10 soil physicochemical indices and 80 for Illumina-based analysis of the fungal microbiome. Soil physicochemical properties and fungal communities exhibited considerable seasonal variation. Ascomycetes, Basidiomycetes, and Mucormycoides dominated. The core microbiome work on the microecological changes in TPPs, and the identified core members contribute to the seasonal succession of communities. The genus Tuber occupies a central position in healthy TPPs. There was a strong correlation between soil physicochemical properties and fungal communities. The genus Tuber showed a positive correlation with Ca, Mg, and total nitrogen, but a negative correlation with total phosphorus and available potassium. This study describes the complex ecological dynamics of soil physicochemical indices and fungal communities occurring during the annual cycle of Tuber indicum, and highlights the succession of core communities in truffle plots, which contribute to better protection of native truffle ecosystems and control of mycorrhizal fungal contamination in artificial truffle plantations in China. IMPORTANCE The spatial and temporal dynamics of soil physicochemical properties and fungal communities associated with four Tuber indicum-producing plots and one non truffle producing plot in four different growing seasons are described. Soil physicochemical properties and fungal communities exhibited considerable seasonal variation. This study examines the complex ecological dynamics of soil physicochemical indices and fungal communities occurring during the annual cycle of Tuber indicum and highlights the succession of core communities in truffle plots, which contributes to better protection of native truffle ecosystems and control of mycorrhizal fungal contamination in artificial truffle plantations in China.

Whitish truffles found in Finland: soil characteristics, and identification based on morphological and molecular properties

The growing demand for truffles has led to a global pursuit for their occurrence in the wild, and studies concerning their cultivation. Although European countries such as Italy, France and Spain have been known for truffle production, truffle hunting is new to Finland. The present study reports for the first time, the findings of Tuber maculatum in Finland on the basis of morphological and molecular analysis. The chemical characteristics of soil samples collected from the truffle sites have also been discussed. The species of the Tuber samples were identified primarily using morphological analysis. Molecular analysis was carried out for the confirmation of the identity of the species. Two phylogenetic trees were constructed based on internal transcribed spacer (ITS) sequences produced in this study and including representative sequences of whitish truffles available in GenBank. The truffles were identified as T. maculatum and T. anniae. This study could be considered as a basis for encouraging research on findings and identification of truffles in Finland.

Fungal and Bacterial Diversity in the Tuber magnatum Ecosystem and Microbiome

Fungi belonging to the genus Tuber produce edible ascocarps known as truffles. Tuber magnatum Picco may be the most appreciated truffle species given its peculiar aroma. While its life cycle is not yet fully elucidated, some studies demonstrated an active role of microorganisms. The main goal of this study was to determine how the T. magnatum microbiome varies across space and time. To address this, we characterized microbial communities associated with T. magnatum through high-throughput amplicon sequencing of internal transcribed spacer (ITS) and 16S rDNAs in three productive natural sites in Italy across 2 years. At each site, four truffles were sampled as well as the soil underneath and at 40, 100, and 200 cm from the harvesting points, to assess for microbial variation between substrates, years, and sites. A statistically significant site-related effect on microbial communities was identified, whereas only the prokaryotic community was significantly affected by the distance of soil from the truffle. Significant differences between sampling years were also found, demonstrating a possible relation among rainfall precipitation and Firmicutes and Actinobacteria. Thirty-six bacterial OTUs in truffles and 11 bacterial OTUs in soils beneath truffles were identified as indicator taxa. As shown for other truffle species, the dominance of Bradyrhizobium, Rhizobium, and Ensifer spp. within the truffle fruiting body suggests an evolutionary adaptation of this microorganism to the genus Tuber. The present work offers novel and relevant insights into the microbial ecology of T. magnatum ecosystems and fruiting bodies. The function and role of these bacteria in the truffle microbiome and life cycle are in need of further investigation.

Marker Substances in the Aroma of Truffles

The aim of this study was to identify specific truffle marker substances within the truffle aroma. The aroma profile of different truffle species was analyzed using static headspace sampling with gas chromatography mass spectrometry analysis (SHS/GC-MS). Possible marker substances were identified, taking the additional literature into account. The selected marker substances were tested in an experiment with 19 truffle dogs. The hypothesis “If trained truffle dogs recognize the substances as supposed truffles in the context of an experiment, they can be regarded as specific” was made. As it would be nearly impossible to investigate every other possible emitter of the same compounds to determine their specificity, this hypothesis was a reasonable approximation. We were interested in the question of what it is the dogs actually search for on a chemical level and whether we can link their ability to find truffles to one or more specific marker substances. The results of the dog experiment are not as unambiguous as could have been expected based on the SHS/GC-MS measurements. Presumably, the truffle aroma is mainly characterized and perceived by dogs by dimethyl sulfide and dimethyl disulfide. However, as dogs are living beings and not analytical instruments, it seems unavoidable that one must live with some degree of uncertainty regarding these results.

MİKOTURİZM VE TOPLUM TEMELLİ TURİZM İLİŞKİSİ ÜZERİNE BİR DEĞERLENDİRME

Mantar turizmi ya da mikoturizm son yıllarda gelişim gösteren alternatif bir turizm ürünü olarak kabul görmektedir. Mikoturizm bir destinasyonu ziyaret eden turistlerin doğa yürüyüşlerini yaparken mantar toplamalarına ve yerel halk ile etkileşimlerine olanak veren, bölgenin sosyal, kültürel ve ekonomik anlamda kalkınmasına katkı sağlayan bir etkinliktir. Dünyada coğrafi özellikler bakımından mantar çeşitliliği açısından oldukça zengin birçok destinasyonda binlerce ziyaretçinin katıldığı çeşitli organizasyonlar, festivaller ve mantar turları düzenlendiği görülmektedir. Böylesine yüksek bir potansiyel arz eden mikoturizmin turizm faaliyetlerinin gelişmesine ve turizm pazarından alınan payın artmasına imkân sağlayacağı öngörülmektedir. Mikoturizm faaliyetleri doğası gereği doğrudan yerel halkı ilgilendirmektedir. Bu noktada az gelişmiş ya da gelişmekte olan ülkelerde kitlesel turizmin olumsuz etkilerine karşı bir çözüm arayışı olarak ifade edilen toplum temelli turizm ön plana çıkmaktadır. Toplum temelli turizm toplumun turizme aktif bir şekilde katılmasını ifade eden ve toplumu sosyal, ekonomik ve çevresel boyutlarda etkileyip ilgili destinasyonun turizmde avantaj sağlamasına katkıda bulunulması anlamına gelen bir kavramdır. Dolayısıyla bu kavramsal araştırmada mikoturizmin toplum temelli turizm ile ilişkisinin değerlendirilmesi amaçlanmıştır. Bu doğrultuda kırsal alanlarda yetişen yenilebilir yabani mantarların bölgenin sosyal, ekonomik ve çevresel olarak kalkınmasında, bölgede çekiciliğin arttırılarak gerçekleştirilecek mantar turları, gastronomik etkinlikler, konaklamalar gibi faaliyetlerde önemli olduğu düşünülmektedir. Ayrıca topluma olan katkısının yanında yetkili devlet otoriteleri ve yerel yönetimlerin bölge ile ilgili altyapı, ulaşım ve ilgili hizmetlerin gerçekleştirilmesi konusunda etkili olması ve turizm sektöründe faaliyet gösteren seyahat acentaları ve tur operatörleri, konaklama ve yeme içme hizmeti veren işletmelerin mikoturizm gibi turistik ürünlere eğilim göstermesi beklenmektedir. Son olarak bu araştırmanın gelecekte gerçekleştirilecek mikoturizm ve toplum temelli turizm ilişkisine yönelik araştırmalara öncülük ederek katkı sağlayacağı öngörülmektedir.

A novel approach to combine food production with carbon sequestration, biodiversity and conservation goals

Land use conflict is a major contributor to unsustainable deforestation rates, with agriculture being the primary driver. Demand for agricultural output is forecast to increase for years to come and the associated deforestation is a key driver in global declines of biodiversity. Moreover, deforestation is contributing to instability of agricultural production systems and reduces our ability to mitigate anthropogenically driven climate change. There is urgency in reducing this land use conflict and the cultivation of ectomycorrhizal fungi (EMF) may provide a partial solution. As an example, here we focus on Lactarius indigo, an edible and historically appreciated species with distribution in the Neotropics and Nearctic. Exploring the geographic spread and associated climate preferences, we describe how cultivation of this species can be combined with forest-based biodiversity and conservation goals. Detailing a full methodology, including mycelium production and how to create trees that may produce the fungus, we explore potential benefits. Combing data from the emerging field of EMF cultivation with nutritional studies, we show that a protein production of 7.31 kg per hectare should be possible, exceeding that of extensive pastoral beef production. In contrast to commercial agriculture, L. indigo cultivation may enhance biodiversity, contribute to conservational goals and create a net sink of greenhouse gases whilst at the same time producing a similar or higher level of protein per unit area than the most common agriculture use of deforested land. With such startling and clear benefits, we call for urgent action to further the development of such novel food production systems.

Eco-archaeological excavation techniques reveal snapshots of subterranean truffle growth

Despite its status as a highly-prized and coveted fungi in gastronomy, many aspects of the subterranean life cycle of the Burgundy truffle (Tuber aestivum) are still unknown, because in situ observations of the formation and maturation of truffle fruitbodies remain difficult. Here, we adopted a suite of archaeological fine-scale excavating techniques to provide unique spatiotemporal snapshots of Burgundy truffle growth at three sites in southern Germany. We also recorded the relative position, fresh weight, maturity level and genotype composition of all excavated fruitbodies. Varying by a factor of thousand, the fresh weight of 73 truffle ranged from 0.1 to 103.2 g, with individual maturity levels likely representing different life cycle stages from completely unripe to fully ripe and even decaying. While only a slightly positive relationship between fruitbody weight and maturity level was found, our results suggest that genetically distinct specimens can exhibit different life cycle stages at the same period of time and under the same environmental conditions. We therefore argue that truffles are likely able to grow, mature and ripe simultaneously between early summer and late winter of the following year. Our case study should encourage further eco-archaeological truffle excavations under different biogeographic settings and at different seasons of the year to gain deeper insights into the fungi's subterranean ecology. The expected cross-disciplinary findings will help truffle hunters and farmers to improve their harvest practices and management strategies.

Ecosystem services provision by Mediterranean forests will be compromised above 2℃ warming

Forests provide a wide range of provisioning, regulating and cultural services of great value to societies across the Mediterranean basin. In this study, we reviewed the scientific literature of the last 30 years to quantify the magnitude of projected changes in ecosystem services provision by Mediterranean forests under IPCC climate change scenarios. We classified the scenarios according to the temperature threshold of 2℃ set by the Paris Agreement (below or above). The review of 78 studies shows that climate change will lead to a general reduction in the provision of regulating services (e.g. carbon storage, regulation of freshwater quantity and quality) and a general increase in the number of fires, burnt areas and generally, an increase in climate-related forest hazards (median + 62% by 2100). Studies using scenarios above the 2℃ threshold projected significantly more negative changes in regulating services than studies using scenarios below this threshold. Main projected trend changes on material services (e.g. wood products), were less clear and depended on (i) whether or not the studies considered the interaction between the rise in temperatures and other drivers (e.g. forest management, CO₂ fertilization) and (ii) differences in productivity responses across the tree species evaluated. Overall, the reviewed studies projected significant reductions in range extent and habitat suitability for the most drought-sensitive forest species (e.g. -88% Fagus sylvatica), while the amount of habitat available for more drought-tolerant species will remain stable or increase; however, the magnitude of projected change for these more xeric species was limited when high-end extreme climatic scenarios were considered (above Paris Agreement). Our review highlights the benefits that climate change mitigation (to keep global mean temperature increase <2℃) can bring in terms of service provision and conservation of Mediterranean forests.

Truffle Market Evolution: An Application of the Delphi Method

Background: The objective of this study was to analyze the current situation of the truffle sector in the main producing countries of the Mediterranean area. Additionally, we identified the challenges for the future and the priority actions to develop the truffle sector in the region. Methods: We used a Delphi process approach, and we selected a total of 17 expert panelists in different positions within the supply chain of the target countries (Spain, France, Italy, Croatia, and Greece). Results: The results obtained allowed us to have a complete description of the current truffle supply chain. We confirmed an evolution of the sector due to the cultivation success of several Tuber species. The maturity of the sector has produced shifts in the roles that form the traditional truffle supply chain operators. We confirmed the trend of a decrease of collectors that hunt truffles in the wild and sell to small travelling buyers, whilst truffle hunters that collect for farmers and specialty wholesalers are emerging. However, a trend of truffle price decrease in the last few years has alerted the sector. Conclusions: As production increases due to truffle cultivation, it will be necessary to promote truffle consumption. We identified actions to develop the truffle sector: (a) strengthen the link between truffles, tourism, and gastronomy; (b) increase the effort at European level for the recognition of truffle production, helping to develop truffle culture and marketing; (c) increase the awareness and consumption of truffles among consumers; and (d) develop tourism workshops for truffle farmers.

Ectomycorrhiza resilience and recovery to extreme flood events in Tuber aestivum and Quercus robur

Very little is known about the impact of flooding and ground saturation on ectomycorrhizal fungi (EcM) and increasing flood events are expected with predicted climate change. To explore this, seedlings inoculated with the EcM species Tuber aestivum were exposed to a range of flood durations. Oak seedlings inoculated with T. aestivum were submerged for between 7 and 65 days. After a minimum of 114-day recovery, seedling growth measurements were recorded, and root systems were destructively sampled to measure the number of existing mycorrhizae in different zones. Number of mycorrhizae did not display correlation with seedling growth measurements. Seven days of submersion resulted in a significant reduction in mycorrhizae numbers and numbers reduced most drastically in the upper zones. Increases in duration of submersion further impacted mycorrhizae numbers in the lowest soil zone only. T. aestivum mycorrhizae can survive flood durations of at least 65 days. After flooding, mycorrhizae occur in higher numbers in the lowest soil zone, suggesting a mix of resilience and recovery. The results will aid in furthering our understanding of EcM but also may aid in conservation initiatives as well as providing insight for those whose livelihoods revolve around the collection of EcM fruiting bodies or cropping of the plant partners.

Predicted climate change will increase the truffle cultivation potential in central Europe

Climate change affects the distribution of many species, including Burgundy and Périgord truffles in central and southern Europe, respectively. The cultivation potential of these high-prized cash crops under future warming, however, remains highly uncertain. Here we perform a literature review to define the ecological requirements for the growth of both truffle species. This information is used to develop niche models, and to estimate their cultivation potential in the Czech Republic under current (2020) and future (2050) climate conditions. The Burgundy truffle is already highly suitable for cultivation on ~ 14% of agricultural land in the Czech Republic (8486 km²), whereas only ~ 8% of the warmest part of southern Moravia are currently characterised by a low suitability for Périgord truffles (6418 km²). Though rising temperatures under RCP8.5 will reduce the highly suitable cultivation areas by 7%, the 250 km² (3%) expansion under low-emission scenarios will stimulate Burgundy truffles to benefit from future warming. Doubling the moderate and expanding the highly suitable land by 352 km² in 2050, the overall cultivation potential for Périgord truffles will rise substantially. Our findings suggest that Burgundy and Périgord truffles could become important high-value crops for many regions in central Europe with alkaline soils. Although associated with uncertainty, long-term investments in truffle cultivation could generate a wide range of ecological and economic benefits.

Potentials of truffles in nutritional and medicinal applications: a review

Truffles, the symbiotic hypogeous edible fungi, have been worldwide regarded as a great delicacy because of their unique flavor and high nutritional value. By identifying their bioactive components such as phenolics, terpenoids, polysaccharides, anandamide, fatty acids, and ergosterols, researchers have paid attention to their biological activities including antitumor, antioxidant, antibacterial, anti-inflammatory, and hepatoprotective activities. In addition, numerous factors have been investigating that can affect the quality and productivity of truffles to overcome their difficulty in culturing and preserving. To provide the information for their potential applications in medicine as well as in functional food, this review summarizes the relevant literature about the biochemical composition, aromatic and nutritional benefits, and biological properties of truffles. Besides, various factors affecting their productivity and quality as well as the preservation methods are also highlighted.

The first comprehensive phylogenetic and biochemical analysis of NADH diphosphatases reveals that the enzyme from Tuber melanosporum is highly active towards NAD

Nudix (for nucleoside diphosphatases linked to other moieties, X) hydrolases are a diverse family of proteins capable of cleaving an enormous variety of substrates, ranging from nucleotide sugars to NAD⁺-capped RNAs. Although all the members of this superfamily share a common conserved catalytic motif, the Nudix box, their substrate specificity lies in specific sequence traits, which give rise to different subfamilies. Among them, NADH pyrophosphatases or diphosphatases (NADDs) are poorly studied and nothing is known about their distribution. To address this, we designed a Prosite-compatible pattern to identify new NADDs sequences. In silico scanning of the UniProtKB database showed that 3% of Nudix proteins were NADDs and displayed 21 different domain architectures, the canonical architecture (NUDIX-like_zf-NADH-PPase_NUDIX) being the most abundant (53%). Interestingly, NADD fungal sequences were prominent among eukaryotes, and were distributed over several Classes, including Pezizomycetes. Unexpectedly, in this last fungal Class, NADDs were found to be present from the most common recent ancestor to Tuberaceae, following a molecular phylogeny distribution similar to that previously described using two thousand single concatenated genes. Finally, when truffle-forming ectomycorrhizal Tuber melanosporum NADD was biochemically characterized, it showed the highest NAD⁺/NADH catalytic efficiency ratio ever described.