Community dynamics of soil-borne fungal communities along elevation gradients in neotropical and palaeotropical forests.

Because of their steep gradients in abiotic and biotic factors, mountains offer an ideal setting to illuminate the mechanisms that underlie patterns of species distributions and community assembly. We compared the composition of taxonomically and functionally diverse fungal communities in soils along five elevational gradients in mountains of the Neo- and Palaeotropics (northern Argentina, southern Brazil, Panama, Malaysian Borneo and Papua New Guinea). Both the richness and composition of soil fungal communities reflect environmental factors, particularly temperature and soil pH, with some shared patterns among neotropical and palaeotropical regions. Community dynamics are characterized by replacement of species along elevation gradients, implying a relatively narrow elevation range for most fungi, which appears to be driven by contrasting environmental preferences among both functional and taxonomic groups. For functional groups dependent on symbioses with plants (especially ectomycorrhizal fungi), the distribution of host plants drives richness and community composition, resulting in important differences in elevational patterns between neotropical and palaeotropical montane communities. The pronounced compositional and functional turnover along elevation gradients implies that tropical montane forest fungi will be sensitive to climate change, resulting in shifts in composition and functionality over time.

Global patterns in endemicity and vulnerability of soil fungi.

Fungi are highly diverse organisms, which provide multiple ecosystem services. However, compared with charismatic animals and plants, the distribution patterns and conservation needs of fungi have been little explored. Here, we examined endemicity patterns, global change vulnerability and conservation priority areas for functional groups of soil fungi based on six global surveys using a high-resolution, long-read metabarcoding approach. We found that the endemicity of all fungi and most functional groups peaks in tropical habitats, including Amazonia, Yucatan, West-Central Africa, Sri Lanka, and New Caledonia, with a negligible island effect compared with plants and animals. We also found that fungi are predominantly vulnerable to drought, heat and land-cover change, particularly in dry tropical regions with high human population density. Fungal conservation areas of highest priority include herbaceous wetlands, tropical forests, and woodlands. We stress that more attention should be focused on the conservation of fungi, especially root symbiotic arbuscular mycorrhizal and ectomycorrhizal fungi in tropical regions as well as unicellular early-diverging groups and macrofungi in general. Given the low overlap between the endemicity of fungi and macroorganisms, but high conservation needs in both groups, detailed analyses on distribution and conservation requirements are warranted for other microorganisms and soil organisms.

Greenhouse seedlings of Alnus showed low host intrageneric specificity and a strong preference for some Tomentella ectomycorrhizal associates.

Ectomycorrhizal (ECM) fungal associates of Alnus are relatively few in comparison with those associated with other tree hosts. The composition of ECM assemblages associated with Alnus seems to change very little across the Northern Hemisphere. However, Alnus-associated ECM assemblages from the Western United States, Mexico, and Argentina tend to differ from those in eastern North America and Europe, presumably due to their different biogeographic histories. Alnus glutinosa is a northern European species subjected to diverse environmental conditions. To address intrageneric host preference within two distantly related Alnus species (Alnus acuminata and A. glutinosa), we tested the ECM colonization on seedlings of both species inoculated with natural soil from A. acuminata forests. Two tomentelloid ECM fungi from A. acuminata natural soils were determined from the anatomotyping and molecular analysis. Both species colonized A. glutinosa seedlings and presented similar relative abundances. Additional soil sequence data from A. acuminata sites suggest that a variety of tomentelloid taxa occur, including several unidentified Tomentella lineages. Maximum-likelihood and Bayesian inference analyses based on internal transcribed spacer (ITS) sequences from various locations do not reflect associations of taxa based on their biogeographic origin, and clades are in general constituted by sequences from diverse regions, including South America, Mexico, USA, and Europe. Results illustrate the probable role of specific tomentelloid fungi in the early colonization of seedlings in A. acuminata forests as well as their importance in the structure of the ECM propagule community at the sites.

Sequestrate fungi from Patagonian Nothofagus forests: Cystangium (Russulaceae, Basidiomycota).

Six species of Cystangium, a genus of sequestrate taxa related to Russula, were collected in Patagonia (Argentina and Chile) during autumn 2001. Two species, C. depauperatum Singer & A.H. Sm. and C. nothofagi (E. Horak) Trappe, Castellano & T. Lebel, were already known from this region, while four new species, C. domingueziae, C. gamundiae, C. grandihyphatum and C. longisterigmatum, are described, illustrated and a key to the species is provided. In addition, sequences of the ITS (rDNA) region were obtained to explore the phylogenetic relationships of our South American Cystangium species.

Large-scale fungal diversity assessment in the Andean Yungas forests reveals strong community turnover among forest types along an altitudinal gradient.

The Yungas, a system of tropical and subtropical montane forests on the eastern slopes of the Andes, are extremely diverse and severely threatened by anthropogenic pressure and climate change. Previous mycological works focused on macrofungi (e.g. agarics, polypores) and mycorrhizae in Alnus acuminata forests, while fungal diversity in other parts of the Yungas has remained mostly unexplored. We carried out Ion Torrent sequencing of ITS2 rDNA from soil samples taken at 24 sites along the entire latitudinal extent of the Yungas in Argentina. The sampled sites represent the three altitudinal forest types: the piedmont (400-700 m a.s.l.), montane (700-1500 m a.s.l.) and montane cloud (1500-3000 m a.s.l.) forests. The deep sequence data presented here (i.e. 4 108 126 quality-filtered sequences) indicate that fungal community composition correlates most strongly with elevation, with many fungi showing preference for a certain altitudinal forest type. For example, ectomycorrhizal and root endophytic fungi were most diverse in the montane cloud forests, particularly at sites dominated by Alnus acuminata, while the diversity values of various saprobic groups were highest at lower elevations. Despite the strong altitudinal community turnover, fungal diversity was comparable across the different zonal forest types. Besides elevation, soil pH, N, P, and organic matter contents correlated with fungal community structure as well, although most of these variables were co-correlated with elevation. Our data provide an unprecedented insight into the high diversity and spatial distribution of fungi in the Yungas forests.

Comprehensive Characterization of Tuber maculatum, New in Uruguay: Morphological, Molecular, and Aromatic Analyses.

Although only a few species of Tuber account for the major truffle sales volume, many species that are not considered delicacies are finding their way to the market, especially in regions where the traditionally appreciated ones do not occur. This is the case for whitish truffles. Specimens of whitish truffles were collected in pecan (Carya illinoinensis) orchards in Uruguay in October 2021. Morphological and molecular methods were used to characterize and assess their identity as Tuber maculatum Vittad. An SPME extraction of volatile compounds and GC-MS analyses were performed to characterize the aromatic profile of these specimens and evaluate their potential applications. Among the 60 VOCs detected, 3-octenone (mushroom odor), 3-octanol (moss, nut, mushroom odor), and 2H-pyran-2-one (no odor), followed by octen-1-ol-acetate (no odor) and 2-undecanone (orange, fresh, green odor) were the major compounds in T. maculatum fruiting bodies. The attributes of exotic edible mushrooms of commercial value in the region are highlighted. In particular, this work emphasizes the characteristics of truffles as a byproduct of pecan cultivation.

Phylogenetic analysis of the genus Modicella reveals an independent evolutionary origin of sporocarp-forming fungi in the Mortierellales.

Most studies of tissue differentiation and development have focused on animals and plants but many fungi form multi-cellular aggregations of spore-bearing tissue known as fruiting bodies or sporocarps. The ability to form sporocarps has arisen independently in several different evolutionary lineages of fungi. Evolutionary relationships of most sporocarp-forming fungi are well known, but the enigmatic zygomycete genus Modicella contains two species of sporocarp-forming fungi for which the phylogenetic affinities have not been explored based on molecular data. Species of Modicella have an uncertain trophic mode and have alternatively been considered members of the order Endogonales (which contains documented species of sporocarp-forming fungi) or the order Mortierellales (which contains no previously documented species of sporocarp-forming fungi). In this study we perform phylogenetic analyses based on ribosomal DNA of Modicella malleola from the Northern Hemisphere and Modicella reniformis from the Southern Hemisphere to determine the evolutionary affinities of the genus Modicella. Our analyses indicate that Modicella is a monophyletic genus of sporocarp-forming fungi nested within the Mortierellales, a group of microfungi with no previously documented sporocarp-forming species. Because Modicella is distantly related to all other known sporocarp-forming fungi, we infer that this lineage has independently evolved the ability form sporocarps. We conclude that the genus Modicella should be a high priority for comparative genomics studies to further elucidate the process of sporocarp formation in fungi.

Ectomycorrhizal fungal communities associated to Nothofagus species in Northern Patagonia.

Ectomycorrhizal fungi constitute an important component of soil biota in Nothofagus forests in Patagonia. However, ectomycorrhizal fungal community is poorly known in this region. Here, we assess biodiversity and community compositions of ectomycorrhizal fungal species associated with Nothofagus dombeyi, N. obliqua and N. alpina. We selected three monospecific Nothofagus forest sites for each species within the boundaries of the Lanin National Park in Northern Patagonia. Ectomycorrhizal fungal species were identified based on morphotyping and rDNA (ITS and 28S rDNA) sequence analysis using both universal and taxon-specific primers. Contrary to previous studies on congeneric host trees, our results showed no significant differences among Nothofagus forest types in terms of fungal biodiversity and community composition. However, altitude had a strong effect on the structure of the ectomycorrhizal fungal community associated with Nothofagus spp.

Aromatic profile of black truffle grown in Argentina: Characterization of commercial categories and alterations associated to maturation, harvesting date and orchard management practices.

Black truffle (Tuber melanosporum) is one of the most appreciated fungi in the world mainly due to its aromatic properties. In the emerging markets such as Argentina, the aroma of locally produced truffles has not been described yet. The volatile organic compounds (VOCs) from 102 black truffles from Argentina were analyzed using solid phase microextraction gas chromatography coupled with mass spectrometer detector (SPME-GC-MS). Several factors such as commercial category, maturity stage, host tree, geographical origin, and aromatic defects detected during classification were also registered and considered. As a result, 79 VOCs were detected, among which 2-methyl-propanal, 2-butanone, 2-methyl-1-propanol, butanal-3-methyl, 3-methyl-1-butanol, 2-methyl-1-butanol were present in high percentage in fresh mature truffles, whereas immature truffles were associated with 3,5-dimethoxytoluene, 2-phenyl-2-butenal, 2,3-dimethoxytoluene. The Argentine black truffles showed significant similarities in their aromatic profile when compared with their Australian and European counterparts, but with some distinctive notes.

Connecting the multiple dimensions of global soil fungal diversity.

How the multiple facets of soil fungal diversity vary worldwide remains virtually unknown, hindering the management of this essential species-rich group. By sequencing high-resolution DNA markers in over 4000 topsoil samples from natural and human-altered ecosystems across all continents, we illustrate the distributions and drivers of different levels of taxonomic and phylogenetic diversity of fungi and their ecological groups. We show the impact of precipitation and temperature interactions on local fungal species richness (alpha diversity) across different climates. Our findings reveal how temperature drives fungal compositional turnover (beta diversity) and phylogenetic diversity, linking them with regional species richness (gamma diversity). We integrate fungi into the principles of global biodiversity distribution and present detailed maps for biodiversity conservation and modeling of global ecological processes.

Towards global patterns in the diversity and community structure of ectomycorrhizal fungi.

Global species richness patterns of soil micro-organisms remain poorly understood compared to macro-organisms. We use a global analysis to disentangle the global determinants of diversity and community composition for ectomycorrhizal (EcM) fungi-microbial symbionts that play key roles in plant nutrition in most temperate and many tropical forest ecosystems. Host plant family has the strongest effect on the phylogenetic community composition of fungi, whereas temperature and precipitation mostly affect EcM fungal richness that peaks in the temperate and boreal forest biomes, contrasting with latitudinal patterns of macro-organisms. Tropical ecosystems experience rapid turnover of organic material and have weak soil stratification, suggesting that poor habitat conditions may contribute to the relatively low richness of EcM fungi, and perhaps other soil biota, in most tropical ecosystems. For EcM fungi, greater evolutionary age and larger total area of EcM host vegetation may also contribute to the higher diversity in temperate ecosystems. Our results provide useful biogeographic and ecological hypotheses for explaining the distribution of fungi that remain to be tested by involving next-generation sequencing techniques and relevant soil metadata.

Differential hypogeous sporocarp production from Nothofagus dombeyi and N. pumilio forests in southern Argentina.

Mycorrhizal fungi that form hypogeous sporocarps are an important component of the temperate forest soil community. In many regions, such as the Nothofagus forest in the Patagonian Andes, this group of fungi has been poorly studied. Here we examined the spring and autumn community composition of "sequestrate fungi", based on sporocarp production in pure forests of Nothofagus dombeyi (evergreen) and N. pumilio (deciduous). We investigated the possible relationships between these communities and environmental factors over 2 y. The rarefaction curves and the minimal richness estimates converged at nearly the same level for each forest type, and the asymptotes suggested that the sampling effort was sufficient to capture most of the hypogeous sporocarp richness in these forest stands. In total 27 species were recovered. Basidiomycota, Ascomycota and Glomeromycota respectively accounted for nine, two and one genera. Species richness of hypogeous sporocarps varied in relation to forest type but not to season (fall and spring), whereas sporocarp biomass varied according to an interaction between season and forest type. Species richness and sporocarp biomass were positively correlated with rainfall and negatively correlated with altitude. In addition sporocarp species richness was positively related to number of trees per transect. We found that two different forest stands, each dominated by different species of Nothofagus, exhibited different hypogeous sporocarp communities.

The species of Scleroderma from Argentina, including a new species from the Nothofagus forest.

Five ectomycorrhizal species of Scleroderma were identified from herbarium and field-collected specimens from Argentina. A new hypogeous species, Scleroderma patagonicum, was recorded in association with native Nothofagus spp. in Patagonia. The epigeous species S. albidum, S. areolatum, S. bovista and S. citrinum were associated with various exotic tree species. A phylogenetic analysis based on the ITS region of Scleroderma species, including S. patagonicum, illustrates its distinct status within Scleroderma, including its placement among species with reticulate spores. Descriptions with SEM images of the spores and a key to the species are provided.

Pattern formation features might explain homoplasy: fertile surfaces in higher fungi as an example.

Fungi show a high degree of morphological convergence. Regarded for a long time as an obstacle for phylogenetic studies, homoplasy has also been proposed as a source of information about underlying morphogenetic patterning mechanisms. The "local-activation and long-range inhibition principle" (LALIP), underlying the famous reaction-diffusion model proposed by Alan Turing in 1952, appears to be one of the universal phenomena that can explain the ontogenetic origin of seriate patterns in living organisms. Reproductive structures of fungi in the class Agaricomycetes show a highly periodic structure resulting in, for example, poroid, odontoid, lamellate or labyrinthic hymenophores. In this paper, we claim that self-organized patterns might underlie the basic ontogenetic processes of these structures. Simulations based on LALIP-driven models and covering a wide range of parameters show an absolute mutual correspondence with the morphospace explored by extant agaricomycetes. This could not only explain geometric particularities but could also account for the limited possibilities displayed by hymenial configurations, thus making homoplasy a direct consequence of the limited morphospace resulting from the proposed patterning dynamics.

Thaxterogaster revisited: A phylogenetic and taxonomic overview of sequestrate Cortinarius from Patagonia.

In the Patagonian region, Cortinarius is the most diverse and abundant genus of ectomycorrhizal fungi with at least 250 species. Sequestrate forms were until recently documented within the genus Thaxterogaster, a genus now known to be polyphyletic, and many were consequently transferred to Cortinarius. Original descriptions were mostly available in German and Spanish and interpretations of morphological structures outdated. Despite recent advances in Cortinarius systematics, the current classification, diversity, and ecology of sequestrate "cortinarioid" fungi in Patagonia remain unclear. The objective of this study was to provide an update on sequestrate Cortinarius of southern South America. We documented each species with morphological descriptions, photographs, basidiospore scanning electron microscopy (SEM) images, and molecular characterization using nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and nuc 28S rDNA (28S) sequence data. Original descriptions of taxa were also translated to English and revised based on fresh collections. We documented 24 species from Patagonia based on molecular data and conducted morphological and phylogenetic analysis for 18 previously described species based on type and reference specimens. In addition, we formally described two new species. Four additional taxa were provisionally determined as new but require further study. New ITS sequence data were produced from eight type specimens. We also provide a new name, Cortinarius gloiodes, nom. nov., for the taxon previously described as Thaxterogaster gliocyclus. In addition to the species treated in detail, we provided additional reference information and discussion on six described species that remained incompletely known or for which no recent collections were found. Of the 24 taxa documented from Patagonia, 15 species were assigned to 12 current sections in the genus Cortinarius. Analysis of spore ultrastructure showed that sequestrate forms of Patagonian Cortinarius lack a true perisporium.

Cortinarius section Thaumasti in South American Nothofagaceae forests.

We studied the South American species of Cortinarius section Thaumasti based on morphological and molecular data. Members of this group can easily be identified in the field because the basidiomata are small and Phlegmacium-like with a bulbous stipe and the universal veil in most species forms a distinct volva at the base of the stipe. The phylogenetic delimitation of the clade was mostly in concordance with the earlier, morphology-based grouping of the South American taxa except that C. chrysophaeus was resolved outside of the clade. Altogether nine species were recognized in the section. Four species, C. chlorophanus, C. coleopus, C. cosmoxanthus, and C. vaginatus, were previously described by other authors, whereas three species, C. chlorosplendidus, C. olivaceovaginatus, and C. subcosmoxanthus, are described here as new. We were able to identify two remaining taxa, but we do not have sufficient morphological data to allow for a formal description. All of the species in C. section Thaumasti form ectomycorrhizal associations with Nothofagaceae. They have been documented from South America and New Zealand. The Patagonian species are considered endemic to the region. A key to the described species is provided.

Systematic study of truffles in the genus Ruhlandiella, with the description of two new species from Patagonia.

Ruhlandiella is a genus of exothecial, ectomycorrhizal fungi in the order Pezizales. Ascomata of exothecial fungi typically lack a peridium and are covered with a hymenial layer instead. Ruhlandiella species have nonoperculate asci and highly ornamented ascospores. The genus was first described by Hennings in 1903 to include the single species, R. berolinensis. Since then, mycologists have uncovered Ruhlandiella species in many locations around the globe, including Australia, Spain, Italy, and the USA. Currently, there are four recognized species: R. berolinensis, R. peregrina, R. reticulata, and R. truncata. All were found near Eucalyptus or Melaleuca trees of Australasian origin. Recently, we discovered two new species of Ruhlandiella in Nothofagaceae forests in South America. They regularly form mitotic spore mats directly on soil in the forests of Patagonia. Here, we formally describe these new species and construct the phylogeny of Ruhlandiella and related genera using a multilocus phylogenetic analysis. We also revise the taxonomy of Ruhlandiella and provide an identification key to accepted species of Ruhlandiella.

Unveiling new sequestrate Cortinarius species from northern Patagonian Nothofagaceae forests based on molecular and morphological data.

Because of systematic sampling campaigns in the northern Patagonian Nothofagaceae forests of Argentina, several specimens of sequestrate fungi were collected. Some of those collections showed phylogenetic affinities and morphological similarities to members of the formerly recognized sequestrate genus Thaxterogaster, currently a synonym of Cortinarius on the basis of molecular data. Comparisons of macro- and micromorphological features and sequences of nuc rDNA internal transcribed spacer (ITS) regions have revealed that these collections belong to formerly undescribed species. The sequences of the four new taxa presented here, Cortinarius flavopurpureus, C. translucidus, C. nahuelhuapensis, and C. infrequens, were combined into a data set including additional sequences generated from herbarium collections and retrieved from public gene databases and analyzed by maximum likelihood and Bayesian inference methods. The four new species were resolved as distinct clades with strong support; at the same time, they showed unique morphological characteristics (hypogeous to subhypogeous habit, complete gasteromycetation, and spore shape and ornamentation) that separate them from previously described Cortinarius species. In addition, several undescribed and/or not previously sequenced species from these forests were detected through phylogenetic analysis of ectomycorrhizal root tip sequences. A key of characters to identify the sequestrate Cortinarius from Patagonia is provided.

Ocurrence of ectomycorrhizal, hypogeous fungi in plantations of exotic tree species in central Argentina.

Eleven hypogeous, ectomycorrhizal species of Basidiomycota, including two new species, and one of the Zygomycota were collected in exotic tree plantations in C6rdoba Province, Argentina. Descomyces fusisporus sp. nov., D. varians sp. nov., Hydnangium archeri (Berk.) Rodway, H. carneum Wallr., Hysterangium gardneri E. Fisch. and Setchelliogaster tenuipes (Setch.) Pouzar were associated with Eucalyptus spp. Endogone lactiflua Berk., Hymenogaster lycoperdineus Vittad., H. griseus Vittad., H. rehsteineri Bucholtz, Rhizopogon couchii A.H. Sm. and R. roseolus (Corda) Th. Fr., were associated with various northern hemisphere tree species. Descriptions are provided to aid identification of the hypogeous fungi in exotic plantations of Argentina.