Tuber Species Research Articles

Tuber magnatum Picco: a new record for the Turkish mycobiota

Tuber magnatum Picco, the Italian white truffle mushroom recorded for the first time in Türkiye, is a rare and economically valuable mushroom. Samples were collected from Sakarya province during field studies in 2024. The samples were identified as T. magnatum according to their macro- and microscopic features. To make molecular confirmation of the species, the samples' ITS1 and ITS4 gene regions were analysed and registered in Genbank with the number PP239641. The sample showed 100% compatibility with other T. magnatum accessions in Genbank. The distributions of Tuber species in Türkiye were given, and their taxonomic features were compared.

Inter-generational consistency of the ectomycorrhizal fungal community in a mixed pine-cedar post-fire stand.

The mutualistic interaction between trees and ectomycorrhizal fungi (EMF) can have a major effect on forest dynamics and specifically on seedling establishment. Here, we compared the EMF community composition associated with the roots of young saplings and mature trees of two co-habiting Pinaceae: Pinus halepensis and Cedrus deodara growing together in a post-fire forest plot, using fungal ITS metabarcoding. We found that the differences in the EMF community between the two sapling groups were mostly attributed to changes in the relative abundance of specific fungal species with little species turnover. Specifically, Tomentella showed high abundance on pine roots while Tuber, Russula and Sebacina were more common on the roots of cedars. The physical proximity to a specific host species was correlated with the EMF community composition of young saplings. Specifically, regardless of the sapling's own identity, the roots of saplings growing next to mature cedars had higher abundance of Tuber species while Tomentella coerulea, Russula densifolia and Tuber nitidum dominated saplings next to mature pines. Cedar saplings' shoot structure was correlated with a specific EMF species. Overall, these results suggest that when germinating next to mature trees, the EMF community of saplings could be determined by extrinsic factors such as the small-scale distribution of mature trees in the forest.

Review on the ethnomedicinal and nutritional value of some wild edible plants used by the tribal of Koraput District of Odisha, India

Due to its abundance of plant genetic resources, Odisha is often called a genetic refuge. However, the south Odisha tribal regions, despite their abundance of natural resources, have received scant ethnobotanical research. Human cultural diversity in Koraput is well-known, and the area is also a biodiversity hotspot for several food crops and forest species. The purpose of this study is to consolidate all available information on the ethnomedical uses of wild plants by indigenous peoples in the Koraput district. The reviewed nutritional analysis studies show that numerous species have high nutrient content, some of which are superior to some domesticated varieties. Wild edible plants are used as indigenous food and remarkably improve the nutritional security of several tribal people of Koraput. However, systematic study on the nutritional potential of these wild edible plants is meager. The present study evaluated the Carbohydrate, Fat, Protein, and Fiber content in selected wild edible plants of Koraput. Research shows that several species of tubers are in danger of extinction and hence included on the IUCN Red List of Threatened and Endangered Species. For this reason, the optimal use of this biodiversity is to meet the inhabitant's present and future food. The medicinal needs depend on extensive phytochemical inquiry, safe conservation, and sustainable use of wild tuber, all require strong community participation, which also fulfills the Sustainable Development Goals (SDG) 2 and 3, i.e., zero hunger and good health and well-being.

Three New Species of Tuber Discovered in Alpine Fir Forests in Yunnan, China.

Three new species of Tuber, T. albicavum, T. laojunshanense, and T. umbilicicavatum belonging to the Puberulum phylogroup, are described based on specimens collected in alpine Abies forests at 3600-4000 m, Northwest Yunnan, China. T. albicavum is distinguished by its ascomata with a single chamber of 0.5-1.8 cm diameter, with an apical opening of 0.2-0.6 cm in diameter, and light golden-brown alveolate reticulate ascospores up to 30 μm in length; T. laojunshanense is characterized by having ascomata with a slightly tomentose surface, sometimes with a white navel, a relatively thick peridium, up to 280 µm, and yellow-brown spores with alveolate reticulate ornamentation, up to 34 µm in length; T. umbilicicavatum is characterized by smooth ascomata with a distinct white navel, a relatively thin peridium, up to 110 µm, and golden or golden-brown alveolate reticulate ascospores, up to 40 μm in length. The molecular analysis of the internal transcribed spacer region also supports that these three new species differ from previously described Tuber species.

Effects of Black and White Mulch on Mycelial Growth of Tuber Species in Korean Field Environment

Truffles, belonging to the genus Tuber, are ectomycorrhizal (ECM) fungi that form underground ascocarps and primarily establish symbiosis with oaks and hazels. The cultivation of Tuber spp. involves transplanting inoculated seedlings that have formed ectomycorrhiza with Tuber species, with mulching being effective for truffle cultivation. In this study, we investigated the effects of mulching on the mycelial growth of four Tuber species (T. himalayense, T. koreanum, T. melanosporum, and T. borchii) in the Korean natural environment, highlighting the potential for Korea as a truffle cultivation site. We developed and tested species-specific primers for quantifying the soil mycelial biomass of Tuber spp. by qRT-PCR, determined the superior mulch color for mycelial growth, and identified the Tuber species exhibiting the highest growth rate in the Korean field environment. Our results demonstrated that white mulch significantly enhanced mycelial growth in Tuber species than black mulch, likely owing to its ability to maintain low soil temperatures, control weeds, and improve host plant growth. Among the Tuber species, T. himalayense showed the greatest growth potential in the Korean natural environment. Additionally, a significant and positive correlation was observed between the mycelial biomass of Tuber species and the growth of inoculated seedlings, as measured by the total stem length and the number of leaves, thereby indicating the importance of symbiosis between ECM fungi and host plants. This study provides valuable insights into truffle cultivation in Korea and highlights the potential of using white mulch to promote mycelial growth, thereby contributing essential data for understanding the appropriate environmental conditions for Tuber spp. cultivation in Korea. Further study is needed to assess the long-term impact of mulching and to explore the effectiveness of other mulching materials.

In vitro interactions between Bradyrhizobium spp. and Tuber magnatum mycelium.

Tuber magnatum is the most expensive truffle, but its large-scale cultivation is still a challenge compared to other valuable Tuber species. T. magnatum mycelium has never been grown profitably until now, which has led to difficulties to studying it in vitro. This study describes beneficial interactions between T. magnatum mycelium and never before described bradyrhizobia, which allows the in vitro growth of T. magnatum mycelium. Three T. magnatum strains were co-isolated on modified Woody Plant Medium (mWPM) with aerobic bacteria and characterised through microscopic observations. The difficulties of growing alone both partners, bacteria and T. magnatum mycelium, on mWPM demonstrated the reciprocal dependency. Three bacterial isolates for each T. magnatum strain were obtained and molecularly characterised by sequencing the 16S rRNA, glnII, recA and nifH genes. Phylogenetic analyses showed that all nine bacterial strains were distributed among five subclades included in a new monophyletic lineage belonging to the Bradyrhizobium genus within the Bradyrhizobium jicamae supergroup. The nifH genes were detected in all bacterial isolates, suggesting nitrogen-fixing capacities. This is the first report of consistent T. magnatum mycelium growth in vitro conditions. It has important implications for the development of new technologies in white truffle cultivation and for further studies on T. magnatum biology and genetics.

Mineral composition in the diversity of tuber species from Bolivia

Mineral composition in the diversity of tuber species from Bolivia

From Farm to Classroom: Tubers as Key Resources in Developing Biology Learning Media Rooted in Banten's Local Culture

This study aims to investigate the diversity of tuber plants used as food by the people in Banten, which are then used as learning content based on local potential. To achieve this goal, we conducted a research and development (RD) method to create various media using the information of tubers diversity in Banten. In the first stage, we collected data on the diversity of tuber plants cultivated by residents in Banten province and their uses. In the second stage, we developed various forms of learning media from the diversity data and the status of plant utilization. Data on diversity was obtained by conducting field observation and interviews with 373 respondents: tuber farmers, traders, intermediaries, processed makers, souvenir shop owners, and homemakers in Banten. Data were analyzed using the descriptive-qualitative method. Information about the diversity of types of tubers, their use for food, and their processing techniques then use as the content on learning media of Biology subject for senior high school on biodiversity, ecosystems, and biotechnology concept. We customize content development to support Biology classes using the Kurikulum Merdeka. The results showed that there were 16 species of tubers used as food, belong to 11 families, such as Dioscoreaceae, Euphorbiaceae, and Convolvulaceae which used as a staple food, snacks, and vegetables. The results of the media development analysis show that diversity data can be applied to various types of multimedia learning media in the biological sciences. While these materials may complement the learning of Biology, careful consideration must be given to the advantages and disadvantages of each medium to ensure that they are appropriate to the learning goals and circumstances of the learners.

Investigation of Aroma Components of Tuber aestivum and Tuber borchii Collected From Different Location in Türkiye

Truffle is an important food source for wild animals and a significant part of the ecosystem, indicating a healthy forest. With their unique aromas, truffles are also a crucial food source for humans. The volatile substances released by Tuber not only appeal to our sense of smell but also contribute to various biological activities. Different aromas result in different tastes; therefore, aroma is essential in defining the organoleptic properties and quality of underground fungi. This research aims to investigate according to the percentage the chemical components considering the habitat and mycorrhizal host tree species of naturally occurring summer truffle Tuber aestivum Vittad. and white truffle Tuber borchii Vittad. in Southwest Anatolia and Marmara regions. For this purpose, the aroma components of T. aestivum and T. borchii collected from two different regions were analyzed using the HS-SPME-GC/MS system. Accordingly, a total of 59 different compounds (volatile organic compounds) were identified, including 20 compounds in T. aestivum from Muğla, 13 compounds in T. aestivum from Kırklareli, 44 compounds in T. borchii from Muğla, and 33 compounds in T. borchii from Kırklareli, belonging to different classes of compounds. While terpenes such as limonene (37.62%), p-cymene (4.79%), and β-pinene (4.12%) were major compounds in T. aestivum collected from Muğla, 2-octen-1-ol (46.78%), 1-octen-3-ol (40.44%), and 3-octanol (2.62%) predominantly constituted the aroma in T. aestivum from Kırklareli. The characteristic sulfur compounds commonly found in Tuber species were present in 42.19% of T. borchii collected from Kırklareli and 12.15% from Muğla. When comparing T. borchii grown in Kırklareli and Muğla, 3-methyl-4,5-dihydrothiophene (29.53% and 6.73%) p-methyl thiobenzaldehyde (2.75% and 5.42%), and methionine (9.91% in Kırklareli, not detected in Muğla) were found in different percentage rates. Based on the data obtained in this study, the classification of both Tuber species, with respect to their geographical origin, was determined using hierarchical cluster analysis (HCA). Accordingly, it is show that of the aroma of Tuber species of the chemical components and the aroma components to the formation should be cultivated after optimizing the ecological conditions that contribute to the symbiotic life of the plant species they provide.

Andean Tubers, Morphological Diversity, and Agronomic Management: A Review

Andean tubers refer to a variety of roots and underground stems cultivated in the Andean region, which spans a significant portion of South America. Among these tubers are Arracacia xanthorrhiza, Tropaeolum tuberosum, Oxalis tuberosa, and Ullucus tuberosus. These tubers exhibit resistance to pests, extreme environmental conditions such as drought or frost, and various soil types. It also displays morphological diversity in terms of shape, color, and size, as well as nutritional variation depending on the specific variety grown and the type of propagation employed. While some agronomic requirements are similar for these tubers, others differ due to factors such as crop management, fertilization techniques, plant characteristics, and other influences that contribute to species-level variations. Therefore, it is important to understand the optimal cultivation conditions for achieving high production yields, comprehending the range of tuber variability, and exploring potential applications for these Andean tubers. It is worth noting that there is a lack of up-to-date information on this subject, highlighting the need for further research and exploration. Efforts have been made to classify and differentiate each tuber based on specific physical characteristics, utilizing reported taxonomic data. This classification system assists producers in distinguishing between the various tuber species and their respective varieties.

Volatile Compound Profiling of Seven Tuber Species Using HS-SPME-GC-MS and Classification by a Chemometric Approach.

Edible mushrooms are important providers of nutrients and are well recognized for their particular organoleptic properties. The volatiles that Tuber releases serve purposes beyond simply appealing to our sense of smell. Truffles have different smells and tastes due to the fact that they contain different volatile components; therefore, aroma is essential in defining the organoleptic properties and quality of truffles. In this research, seven Tuber species, namely, Tuber ferrugineum, Tuber nitidum, Tuber excavatum, Tuber rufum, Tuber puberulum, Tuber aestivum, and Tuber borchii were selected. The primary objective of this study was to carry out the first in-depth investigation of the volatile compounds and chemometric analysis of seven truffle species from the Tuber genus that are grown in Turkey. The SPME headspace combined with GC-MS analysis identified 60 volatiles from different classes, with the abundance of terpenes being followed in a decreasing order by alcohols, aldehydes, sulfides, ketones, and other aromatic compounds. According to the chemometric analysis, methional, 3-methyl-4,5-dihydrothiophene, p-(methylthio) benzaldehyde, 3-octene, linalyl acetate, methyl caproate, and β-trans-ocimene could be highlighted as markers for T. borchii grown in Turkey. This investigation was conducted for the first time using T. ferrugineum, T. puberulum, and T. nitidum. The comparison of the volatile profile of these tubers' species displayed branded differences. Thus, the knowledge gained from this research may pave the way to identify the key aroma contributors in the chosen Tuber species.

Ectomycorrhizal Fungal Community and Ascoma Production in a Declining Tuber borchii Plantation.

Tuber borchii is an edible ectomycorrhizal mushroom of considerable economic value. Its cultivation has become popular in recent years, but there are few studies on the factors affecting its productivity. In this work, the ascoma production and the ectomycorrhizal (ECM) community of a T. borchii plantation, established in an intensive farming area where this truffle is not naturally present, were studied. Tuber borchii production drastically declined from 2016 to 2021, and ascomata of other Tuber species (T. maculatum and T. rufum) were found from 2017. Molecular characterization of ectomycorrhizae carried out in 2016 identified 21 ECM fungal species, of which T. maculatum (22%) and Tomentella coerulea (19%) were the most abundant. Tuber borchii ectomycorrizae (16%) were almost entirely confined to the fruiting points. The diversity and structure of the ECM community on Pinus pinea were significantly different from those observed on hardwood trees. The obtained results suggest that T. maculatum (a native of the study site) tends to replace T. borchii through a mechanism of competitive exclusion. Although T. borchii cultivation is possible in suboptimal environments, particular care should be taken to limit competition with ECM fungi more suitable for local conditions.

Tuber indicum and T. lijiangense colonization differentially regulates plant physiological responses and mycorrhizosphere bacterial community of Castanopsis rockii seedlings.

Black truffles and white truffles are widely studied around the world, but their effects on plant growth and physiological responses, and on the mycorrhizosphere bacterial community of the host plant remain unclear. Here, mycorrhizal colonization of Castanopsis rockii by Tuber indicum (Chinese black truffle) and T. lijiangense (Chinese white truffle), respectively, was induced in a greenhouse study, and their effects on host growth, physiological responses and mycorrhizosphere bacterial communities were compared. The results show that colonization of both Tuber species significantly increased leaf photosynthetic rate, leaf P concentration and mycorrhizosphere acid phosphatase activity, as well as richness of mycorrhizosphere bacterial communities of C. rockii seedlings. However, T. indicum colonization on the one hand significantly decreased tartrate content, bacterial acid phosphatase, phoC gene abundance in the mycorrhizosphere, and peroxidase (POD) activity of ectomycorrhizal root tips, but on the other hand increased mycorrhizosphere pH and superoxide dismutase (SOD) of ectomycorrhizal root tips, compared to T. lijiangense colonization. Moreover, principal coordinate and β-diversity analyses show significant differences in mycorrhizosphere bacterial community composition between T. indicum and T. lijiangese colonized C. rockii seedlings. Finally, the relative abundance of the bacterium Agromyces cerinus significantly correlated to mycorrhizosphere acid phosphatase activity and leaf P concentration, suggesting that this bacterium might play an important role in P mobilization and acquisition. Overall, these results suggest that T. indicum and T. lijiangense differently regulate their host plant's physiological responses and mycorrhizosphere bacterial community.

Development of embodied capital: Diet composition, foraging skills, and botanical knowledge of forager children in the Congo Basin

The embodied capital theory states that the extended juvenile period has enabled human foragers to acquire the complex foraging skills and knowledge needed to obtain food. Yet we lack detailed data on how forager children develop these skills and knowledge. Here, we examine the seasonal diet composition, foraging behavior, and botanical knowledge of Mbendjele BaYaka forager children in the Republic of the Congo. Our data, acquired through long-term observations involving full-day focal follows, show a high level of seasonal fluctuation in diet and foraging activities of BaYaka children, in response to the seasonal availability of their food sources. BaYaka children foraged more than half of the time independent from adults, predominantly collecting and eating fruits, tubers, and seeds. For these most-consumed food types, we found an early onset of specialization of foraging skills in children, similar to the gendered division in foraging in adults. Specifically, children were more likely to eat fruit and seed species when there were more boys and men in the group, and girls were more likely than boys to collect tuber species. In a botanical knowledge test, children were more accurate at identifying plant food species with increasing age, and they used fruits and trunks for species identification, more so than using leaves and barks. These results show how the foraging activities of BaYaka children may facilitate the acquisition of foraging skills and botanical knowledge and provide insights into the development of embodied capital. Additionally, BaYaka children consumed agricultural foods more than forest foods, probably reflecting BaYaka’s transition into a horticultural lifestyle. This change in diet composition may have significant consequences for the cognitive development of BaYaka children.

Tuber wenchuanense, a holarctic truffle with a wide range of host plants and description of its ectomycorrhiza with spruce

Tuber wenchuanense ascomata (Ascomycota, Pezizales), a species originally described from Sichuan (China), were found in the Tatra Mountains in southern Poland. The purpose of this work was to (i) report and assess the first case of the holarctic natural distribution of a Tuber species, (ii) amend the original description of the species, (iii) summarize data on its host plants and (iv) describe its ectomycorrhiza. Specimens of Tuber wenchuanense from the Tatra Mountains were studied morphologically and molecularly. The ectomycorrhiza of this truffle with Picea abies was described for the first time. The distribution of T. wenchuanense, which is reconstructed based on sequences deposited in the publicly available nucleotide sequence databases, makes it the first holarctic Tuber species and the one with the northernmost habitat. In fact, its habitat is confined mainly to mountain coniferous forests and alpine and arctic tundra; although, according to known observations, the fruiting bodies of T. wenchuanense can be produced only under conifers. Based on the sequences of the internal transcribed spacer, this species appears to have low genetic variability over the entire distribution range. The phylogenetic tree showed that some of the unidentified phylotypes from the Rufum clade found by other researchers belong to T. wenchuanense. The ecological implications of these findings are discussed.

The effects of teak shades at different ages on early growth of 3 tuber species in Semin Village, Gunung Kidul

The government’s efforts in maintaining the food security includes developing alternative food sources, developing local food crops and improving the use of dry land for food crops cultivation. Planting tubers are common in private forest lands, such as in Semin Village, where arrowroot (Maranta arundinacea L.) can live under teak (Tectona grandis L.) stands. Based on this, a trial was conducted on planting three species of tubers, namely arrowroot/garut, canna/ganyong (Canna discolor Lindl.), and yam/gembili (Dioscorea esculenta (Lour.) Burk.) under teak stands. In mixed cropping patterns, there are limitations in obtaining light and nutrient sources for the plants underneath. Therefore, this study aimed to determine the morphological adaptation of three species of tubers, especially under the shade of teak, at different ages. The research design was completely randomized (CRD), while data analysis used two-way Anova. The results showed that the difference in relative light intensity (RLI) at eight weeks after planting had a significant effect on the height, the number of shoots or stems, and the number of leaves of the tested tubers. The size of the plant and the diameter of the stem showed the highest average under the shade of seven years teak stand, the contrary, the highest number of shoots or stems found in the open areas.

Species diversity, phylogeny, endemism and geography of the truffle genus Tuber in China based on morphological and molecular data.

The genus Tuber (Tuberaceae, Pezizales) is an important fungal group of Ascomycota both economically and ecologically. However, the species diversity, phylogenetic relationships, and geographic distribution of Tuber species in China remains poorly understood, primarily because descriptions of many new species relied heavily on morphological features with molecular data either not sought or ignored. The misapplication of European and North American names further added to confusion regarding the taxonomy of Chinese Tuber species. In this study, we examined more than 1 000 specimens from China, and performed a comprehensive phylogenetic analysis for Chinese Tuber species using ITS sequences and multilocus sequence data. To infer the phylogeny of Chinese Tuber spp., 11 molecular datasets were assembled, including a concatenated internal transcribed spacers of the nuc rDNA (ITS), nuc rDNA 28S subunit (LSU), translation elongation factor 1-alpha (tef1-α), and RNA polymeraseII subunit (rpb2) dataset as well as 10 ITS datasets (totally including 1 435 sequences from 828 collections with 597 newly generated sequences, and 168 sequences from the types of 63 species). Our phylogenetic tree based on a concatenated multilocus dataset revealed that all Chinese Tuber species nested in nine phylogenetic clades (phylogroups), including Aestivum, Excavatum, Latisporum, Macrosporum, Maculatum, Melanosporum, Puberulum, Rufum and Turmericum. Of these, five phylogroups (Macrosporum, Maculatum, Melanosporum, Puberulum and Rufum) are shared across the continents of Asia, Europe and North America; two phylogroups (Aestivum and Excavatum) are shared by Europe and Asia; and the phylogroups Turmericum and Latisporum are endemic only to Asia. Phylogenetic trees based on 10 ITS datasets confirmed the presence of at least 82 phylogenetic species in China. Of these, 53 are identified as known species, including three new records for China, and 25 species are identified as new to science. Of the new species, nine are described and illustrated in this paper, and the others remain unnamed due to the paucity or absence of ascomatal materials. Accordingly, the confirmed, excluded and doubtful Tuber species in China are discussed. Tuber species showed high endemism. Of the 82 phylogenetic species found in China, 68 species occur only in China, six species are also found in other regions in Asia, and only eight species (T. anniae, T. excelsum-reticulatum, T. formosanum, T. maculatum, T. wenchuanense, Tuber sp. CHN-3, Tuber sp. CHN-10 and Tuber sp. CHN-11) are shared with other continents. Most Tuber species have a small and limited distribution in China, but a few, such as T. formosanum and T. parvomurphium, are widely distributed across China. Some phylogenetically closely related species, such as T. liaotongense and T. subglobosum, as well as T. xuanhuaense and T. lijiangense, show a pattern of allopatric distribution.

Species diversity, phylogeny, endemism and geography of the truffle genus Tuber in China based on morphological and molecular data

The genus Tuber (Tuberaceae, Pezizales) is an important fungal group of Ascomycota both economically and ecologically. However, the species diversity, phylogenetic relationships, and geographic distribution of Tuber species in China remains poorly understood, primarily because descriptions of many new species relied heavily on morphological features with molecular data either not sought or ignored. The misapplication of European and North American names further added to confusion regarding the taxonomy of Chinese Tuber species. In this study, we examined more than 1 000 specimens from China, and performed a comprehensive phylogenetic analysis for Chinese Tuber species using ITS sequences and multilocus sequence data. To infer the phylogeny of Chinese Tuber spp., 11 molecular datasets were assembled, including a concatenated internal transcribed spacers of the nuc rDNA (ITS), nuc rDNA 28S subunit (LSU), translation elongation factor 1-alpha ( tef1-α), and RNA polymerase II subunit ( rpb2) dataset as well as 10 ITS datasets (totally including 1 435 sequences from 828 collections with 597 newly generated sequences, and 168 sequences from the types of 63 species). Our phylogenetic tree based on a concatenated multilocus dataset revealed that all Chinese Tuber species nested in nine phylogenetic clades (phylogroups), including Aestivum, Excavatum, Latisporum, Macrosporum, Maculatum, Melanosporum, Puberulum, Rufum and Turmericum. Of these, five phylogroups ( Macrosporum, Maculatum, Melanosporum, Puberulum and Rufum) are shared across the continents of Asia, Europe and North America; two phylogroups ( Aestivum and Excavatum) are shared by Europe and Asia; and the phylogroups Turmericum and Latisporum are endemic only to Asia. Phylogenetic trees based on 10 ITS datasets confirmed the presence of at least 82 phylogenetic species in China. Of these, 53 are identified as known species, including three new records for China, and 25 species are identified as new to science. Of the new species, nine are described and illustrated in this paper, and the others remain unnamed due to the paucity or absence of ascomatal materials. Accordingly, the confirmed, excluded and doubtful Tuber species in China are discussed. Tuber species showed high endemism. Of the 82 phylogenetic species found in China, 68 species occur only in China, six species are also found in other regions in Asia, and only eight species ( T. anniae, T. excelsum-reticulatum, T. formosanum, T. maculatum, T. wenchuanense, Tuber sp. CHN-3, Tuber sp. CHN-10 and Tuber sp. CHN-11) are shared with other continents. Most Tuber species have a small and limited distribution in China, but a few, such as T. formosanum and T. parvomurphium, are widely distributed across China. Some phylogenetically closely related species, such as T. liaotongense and T. subglobosum, as well as T. xuanhuaense and T. lijiangense, show a pattern of allopatric distribution.

Presence and production of Tuber aestivum in relation with the soil environment of a semi-natural experimental truffle orchard in Spoleto, Central Italy

Truffles produced by Tuber species (Ascomycota) represent an additional income in economically marginal areas, especially if cultivating mycorrhized seedlings in dedicated truffle orchards. However, despite the great progress made in cultivation, truffle production has not increased substantially. One of the reasons may be the lack of knowledge on soil as a key component of truffle species habitats. This is the case for Tuber aestivum, whose soil environment has been studied less than those of T. magnatum and T. melanosporum due to the lower economic value of its ascocarps. We did the present study in an experimental truffle orchard submitted to a light tillage before our investigation and characterized by the presence of different host tree species and soil variation in space. We assessed whether truffle production and T. aestivum mycelial DNA in soil varied depending on symbiont tree species, soil type or both by comparing sub-areas characterized by the presence/absence of: i) two landforms; ii) four host tree species; and iii) the truffle brûlé, i.e., the area lacking herbaceous cover when root colonization by T. aestivum occurs.Results show that combined variations in chemical and physical properties determined by soil forming processes can make an area suitable or not for T. aestivum. The establishment of brûlé and higher ascocarp production occurred in the more alkaline and less compact soil type, where the resistance to ascocarp volume enlargement is lower and aeration of the soil surface layer is higher. The tillage carried out in the truffle orchard presumably mimicked the effect of the brûlé on the soil structure, allowing the enlargement of the productive area outside the brûlé itself and showing how the management of a truffle plantation, even if sub-optimal for T. aestivum colonization, can influence its productive capacity. Our results further suggest that even in the best environmental conditions not all host trees will enter in production, while in less suitable soil conditions little or no production should be expected.

Mitospore formation on pure cultures of Tuber japonicum (Tuberaceae, Pezizales) in vitro.

The members of the genus Tuber are Ascomycota that form ectomycorrhizal associations with various coniferous and broadleaf tree species. In the teleomorphic stage, the species of the genus produce fruit bodies known as true truffles. Recent studies have discovered mitosporic structures, including spore mats, of several Tuber species on forest soils, indicating the presence of a cryptic anamorphic stage or an unknown reproductive strategy. Here, we report in vitro mitospore formation on the mycelium of T. japonicum, which belongs to the Japonicum clade, collected in several regions in Japan. Twenty of the 25 strains formed mitospores on modified Melin-Norkrans agar medium, indicating that mitospore formation is likely a common trait among strains of T. japonicum. The fungus forms repeatedly branched conidiophores on aerial hyphae on colonies and generates holoblastic mitospores sympodially on the terminal and near apical parts and/or occasionally on the middle and basal parts of the conidiogenous cells. Mitospores are hyaline and elliptical, obovate, oblong, or occasionally bacilliform, with a vacuole and often distinct hilar appendices. Formation of mitospores by T. japonicum in vitro is useful in understanding the functions of mitospores in the genus Tuber under controlled environmental conditions.