Word-wide meta-analysis of Quercus forests ectomycorrhizal fungal diversity reveals southwestern Mexico as a hotspot

Ectomycorrhizal fungal communities in natural and urban ecosystems: Quercus humboldtii as a study case in the tropical Andes

Worldwide urban landscapes are expanding because of the growing human population. Urban ecosystems serve as habitats to highly diverse communities. However, studies focusing on the diversity and structure of ectomycorrhizal communities are uncommon in this habitat. In Colombia, Quercus humboldtii Bonpl. is an ectomycorrhizal tree thriving in tropical montane forests hosting a high diversity of ectomycorrhizal fungi. Q. humboldtii is planted as an urban tree in Bogotá (Colombia). We studied how root-associated fungal communities of this tree change between natural and urban areas. Using Illumina sequencing, we amplified the ITS1 region and analyzed the resulting data using both OTUs and Amplicon Sequence Variants (ASVs) bioinformatics pipelines. The results obtained using both pipelines showed no substantial differences between OTUs and ASVs for the community patterns of root-associated fungi, and only differences in species richness were observed. We found no significant differences in the species richness between urban and rural sites based on Fisher's alpha or species-accumulation curves. However, we found significant differences in the community composition of fungi present in the roots of rural and urban trees with rural communities being dominated by Russula and Lactarius and urban communities by Scleroderma, Hydnangium, and Trechispora, suggesting a high impact of urban disturbances on ectomycorrhizal fungal communities. Our results highlight the importance of urban trees as reservoirs of fungal diversity and the potential impact of urban conditions on favoring fungal species adapted to more disturbed ecosystems.

New Ascomycetes from the Mexican Tropical Montane Cloud Forest

The tropical montane cloud forest is the most diverse and threatened vegetation type in Mexico. In the last decade, the number of described Ascomycetes species has notably increased, reaching more than 1300 species. This study describes six new species based on their molecular and morphological characteristics. Our results suggest that Mexico has the highest number of described species in the Neotropics. However, many other Mexican lineages still need to be described.

Novelties in Macrofungi of the Tropical Montane Cloud Forest in Mexico

The tropical montane cloud forest in Mexico is the most diverse and threatened ecosystem. Mexican macrofungi numbers more than 1408 species. This study described four new species of Agaricomycetes (Bondarzewia, Gymnopilus, Serpula, Sparassis) based on molecular and morphological characteristics. Our results support that Mexico is among the most biodiverse countries in terms of macrofungi in the Neotropics.

Exploring the Relationships between Macrofungi Diversity and Major Environmental Factors in Wunvfeng National Forest Park in Northeast China

In this paper, we analyze the macrofungi communities of five forest types in Wunvfeng National Forest Park (Jilin, China) by collecting fruiting bodies from 2019–2021. Each forest type had three repeats and covered the main habitats of macrofungi. In addition, we evaluate selected environmental variables and macrofungi communities to relate species composition to potential environmental factors. We collected 1235 specimens belonging to 283 species, 116 genera, and 62 families. We found that Amanitaceae, Boletaceae, Russulaceae, and Tricholomataceae were the most diverse family; further, Amanita, Cortinarius, Lactarius, Russula, and Tricholoma were the dominant genera in the area. The macrofungi diversity showed increasing trends from Pinus koraiensis Siebold et Zuccarini forests to Quercus mongolica Fischer ex Ledebour forests. The cumulative species richness was as follows: Q. mongolica forest A > broadleaf mixed forest B > Q. mongolica, P. koraiensis mix forest D (Q. mongolica was the dominant species) > Q. mongolica and P. koraiensis mix forest C (P. koraiensis was the dominant species) > P. koraiensis forest (E). Ectomycorrhizal fungi were the dominant functional group; they were mainly in forest type A and were influenced by soil moisture content and Q. mongolica content (p < 0.05). The wood-rotting fungus showed richer species diversity than other forest types in broadleaf forests A and B. Overall, we concluded that most fungal communities preferred forest types with a relatively high Q. mongolica content. Therefore, the deliberate protection of Q. mongolica forests proves to be a better strategy for maintaining fungal diversity in Wunvfeng National Forest Park.

Greetings from belowground: two new species of truffles in the genus Pachyphlodes (Pezizaceae, Pezizales) from México

Pachyphlodes is a lineage of ectomycorrhizal, hypogeous, sequestrate ascomycete fungi native to temperate and subtropical forests in the Northern Hemisphere. Pachyphlodes species form ectomycorrhizae mainly with Fagales hosts. Here we describe two new species of Pachyphlodes, P.brunnea, and P.coalescens, based on morphological and phylogenetic analysis. Pachyphlodesbrunnea is distributed in the states of Tamaulipas and Nuevo León in northern México, occurring with Quercus and Juglans species. It is characterized by its dark brown peridium, white gleba, and spores with capitate columns. Pachyphlodescoalescens is distributed in the states of Michoacán and Tlaxcala in central and southwestern México co-occurring with Quercus and is distinguished by its reddish-brown peridium, light yellow gleba, and spore ornamentation. Both species, along with P.marronina, constitute the Marronina clade. This clade contains North American species characterized by a brown peridium and spores ornamented with capitate spines to coalesced spine tips that form a partial perispore.

Morphological and genetic diversification of Russula floriformis, sp. nov., along the Isthmus of Panama

Species of Russula are ubiquitous members of ectomycorrhizal fungal communities in tropical ecosystems. However, an important part of the total tropical diversity of this genus and its biogeographic patterns is unknown due to the lack of studies on Russula in tropical ecosystems. We combined molecular, morphological, ecological, and biogeographic data to elaborate concepts for two new subspecies of R. floriformis (subsection Substriatinae). Russula floriformis subsp. floriformis and R. floriformis subsp. symphoniae are described as new from montane forest dominated by Quercus and/or Oreomunnea (Fagales) from Colombia and Panama, respectively. Phylogenies were constructed using nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS), D1-D2 domains of nuc 28S rDNA (28S), and partial regions of the second largest subunit of RNA polymerase II (rpb2) and translation elongation factor 1-alpha (tef1). Similar environmental conditions, similar morphology, and an ITS sequence similarity higher than 99% with only three different positions indicate that these two subspecies are closely related. Detailed observations of microscopic structures and analyses of further DNA loci, however, revealed morphological and molecular characteristics that allow distinguishing the two subspecies of R. floriformis. Spatial distribution and phylogenetic proximity of the two Russula subspecies and their ectomycorrhizal hosts, i.e., species of Quercus, suggest that their diversification is a result of comigration, adaptation, and geographic isolation along the Isthmus of Panama during the Pliocene and Pleistocene.

The Limited Establishment of Native Ectomycorrhizal Fungi in Exotic Eucalyptus spp. Stands in Japan

Host specificity may potentially limit the distribution expansion of ectomycorrhizal (ECM) fungi into areas where their original host plants are absent. To test this hypothesis, we investigated whether populations of native ECM fungi may establish in stands of exotic host trees, namely those of the Eucalyptus species, in Japan. ECM fungal communities associated with eucalyptus and surrounding native host species (Pinus thunbergii and Fagaceae spp.) were investigated at two sites; one site in which eucalyptus and native trees were growing in isolation, and a second site in which these species were mixed. To identify fungal taxa, the nuclear ribosomal internal transcribed spacer region 1 was sequenced for the ECM fungi from the root tips and clustered into operational taxonomic units (OTUs). To confirm whether the retrieved OTUs were native to Japan, they were queried against the entire database of the National Center for Biotechnology Information, UNITE, and GlobalFungi, whereby sampling locations and associated hosts were obtained from sequences with ≥97% similarity. Eucalyptus trees were associated with seven and 12 ECM fungal OTUs, including putatively exotic OTUs in isolated and mixed sites, respectively. Among the 36 and 63 native ECM fungal OTUs detected from native hosts at isolated and mixed sites, only one OTU was shared with eucalyptus at the respective sites. This means that most native ECM fungi in Japan may be incapable of forming an association with exotic Eucalyptus spp. Notably, even ECM fungi associated with both Pinus and Quercus were not detected from eucalyptus, suggesting that host-fungus incompatibility is determined not only by host phylogenetic relatedness but also by host biogeographic affinities. Our findings show that the incompatibility with eucalyptus as well as dispersal limitation may prevent the distribution expansion of native ECM fungi in Japan into the distribution ranges of Eucalyptus spp., where the original hosts are absent.

Six new species and reports of Hydnum (Cantharellales) from eastern North America

Five species of Hydnum have been generally recognized from eastern North America based on morphological recognition: H.albidum, H.albomagnum, H.repandum and varieties, H.rufescens, and H.umbilicatum. Other unique North American species, such as H.caespitosum and H.washingtonianum, are either illegitimately named or considered synonymous with European taxa. Here, seventeen phylogenetic species of Hydnum are detected from eastern North America based on a molecular phylogenetic survey of ITS sequences from herbarium collections and GenBank data, including environmental sequences. Based on current distribution results, sixteen of these species appear endemic to North America. Of these, six species are described as new: H.alboaurantiacum, H.cuspidatum, H.ferruginescens, H.subconnatum, H.subtilior, and H.vagabundum. Geographic range extensions and taxonomic notes are provided for five additional species recently described as new from eastern North America. A new name, H.geminum, is proposed for H.caespitosum Banning ex Peck, non Valenti. Overall, species of Hydnum are best recognized by a combination of morphological and molecular phylogenetic analyses. Taxonomic descriptions are provided for seventeen species, including epitype designations for H.albidum, H.albomagnum, and H.umbilicatum, taxa described more than 100 years ago, and molecular annotation of the isotype of H.washingtonianum. Photographs and a key to eastern North American Hydnum species are presented.

Ectomycorrhizal associations in the tropics - biogeography, diversity patterns and ecosystem roles

Contents Summary 1076 I. Introduction 1076 II. Historical overview 1077 III. Identities and distributions of tropical ectomycorrhizal plants 1077 IV. Dominance of tropical forests by ECM trees 1078 V. Biogeography of tropical ECM fungi 1081 VI. Beta diversity patterns in tropical ECM fungal communities 1082 VII. Conclusions and future research 1086 Acknowledgements 1087 References 1087 SUMMARY: Ectomycorrhizal (ECM) associations were historically considered rare or absent from tropical ecosystems. Although most tropical forests are dominated by arbuscular mycorrhizal (AM) trees, ECM associations are widespread and found in all tropical regions. Here, we highlight emerging patterns of ECM biogeography, diversity and ecosystem functions, identify knowledge gaps, and offer direction for future research. At the continental and regional scales, tropical ECM systems are highly diverse and vary widely in ECM plant and fungal abundance, diversity, composition and phylogenetic affinities. We found strong regional differences among the dominant host plant families, suggesting that biogeographical factors strongly influence tropical ECM symbioses. Both ECM plants and fungi also exhibit strong turnover along altitudinal and soil fertility gradients, suggesting niche differentiation among taxa. Ectomycorrhizal fungi are often more abundant and diverse in sites with nutrient-poor soils, suggesting that ECM associations can optimize plant nutrition and may contribute to the maintenance of tropical monodominant forests. More research is needed to elucidate the diversity patterns of ECM fungi and plants in the tropics and to clarify the role of this symbiosis in nutrient and carbon cycling.

Host Phylogeny Is a Major Determinant of Fagaceae-Associated Ectomycorrhizal Fungal Community Assembly at a Regional Scale

Environmental filtering (niche process) and dispersal limitation (neutral process) are two of the primary forces driving community assembly in ecosystems, but how these processes affect the Fagaceae-associated ectomycorrhizal (EM) fungal community at regional scales is so far poorly documented. We examined the EM fungal communities of 61 plant species in six genera belonging to the Fagaceae distributed across Chinese forest ecosystems (geographic distance up to ∼3,757 km) using Illumina Miseq sequencing of ITS2 sequences. The relative effects of environmental filtering (e.g., host plant phylogeny, soil and climate) and dispersal limitation (e.g., spatial distance) on the EM fungal community were distinguished using multiple models. In total, 2,706 operational taxonomic units (OTUs) of EM fungi, corresponding to 54 fungal lineages, were recovered at a 97% sequence similarity level. The EM fungal OTU richness was significantly affected by soil pH and nutrients and by host phylogeny. The EM fungal community composition was significantly influenced by combinations of host phylogeny, spatial distance, soil and climate. Furthermore, host phylogeny had the greatest effect on EM fungal community. The study suggests that the assembly of the EM fungal community is governed by both environmental filtering and dispersal limitation, with host effect being the most important determinant at the regional scale.