Search

Functional traits influence the assembly of microbial communities, but identifying these traits in the environment has remained challenging. We studied ectomycorrhizal fungal (EMF) communities inhabiting Populus trichocarpa roots distributed across a precipitation gradient in the Pacific Northwest, USA. We profiled these communities using taxonomic (meta-barcoding) and functional (metagenomic) approaches. We hypothesized that genes involved in fungal drought-stress tolerance and fungal mediated plant water uptake would be most abundant in drier soils. We were unable to detect support for this hypothesis; instead, the abundance of genes involved in melanin synthesis, hydrophobins, aquaporins, trehalose-synthases, and other gene families exhibited no significant shifts across the gradient. Finally, we studied variation in sequence homology for certain genes, finding that fungal communities in dry soils are composed of distinct aquaporin and hydrophobin gene sequences. Altogether, our results suggest that while EMF communities exhibit significant compositional shifts across this gradient, coupled functional turnover, at least as inferred using community metagenomics is limited. Accordingly, the consequences of these distinct EMF communities on plant water uptake remain critically unknown, and future studies targeting the expression of genes involved in drought stress tolerance are required.

To understand the roles of charcoal and ectomycorrhizal fungi (ECMF) on tree growth, which relates to the rehabilitation of forest ecosystems after forest fires, two experiments were set up in this study, the first was to determine the correct amount of charcoal for Japanese larch (Larix kaempferi Sarg.) seedling growth by applying oak charcoal to basic soil medium at ratios of 1:1, 1:2, 1:4 and 1:8 by volume. The second experiment investigated the combined effects of four types of charcoal: derived from oak wood, husks of buckwheat, rice and activated charcoal of larch wood, and two types of ECMF: Pt (Pisolithus tinctorius Pers.) and Ec (Pt + Rhizopogon spp. + Laccaria spp. + Scleroderma spp.) on the growth of Japanese larch seedlings. Our results show that growth was significantly stressed by large amounts charcoal applications. There were significant variations among the four types of charcoal on growth. We concluded that the addition of charcoal was the critical factor that influenced larch growth and ECMF formation. Rice charcoal and Ec stimulates the growth and nitrogen uptake of Japanese larch seedlings, thus the most suitable fungus and charcoal for practices is Ec-rice charcoal (1: 8 charcoal to basic soil). [ABSTRACT FROM AUTHOR]

ABSTRACT Specific interactions between bacteria and ectomycorrhizal fungi (EcMF) can benefit plant health, and saprotrophic soil fungi represent a potentially antagonistic guild to these mutualisms. Yet there is little field‐derived experimental evidence showing how the relationship among these three organismal groups manifests across time. To bridge this knowledge gap, we experimentally reduced EcMF in forest soils and monitored both bacterial and fungal soil communities over the course of a year. Our analyses demonstrate that soil trenching shifts the community composition of fungal communities towards a greater abundance of taxa with saprotrophic traits, and this shift is linked to a decrease in both EcMF and a common ectomycorrhizal helper bacterial genus, Burkholderia, in a time‐dependent manner. These results not only reveal the temporal nature of a widespread tripartite symbiosis between bacteria, EcMF and a shared host tree, but they also refine our understanding of the commonly referenced ‘Gadgil effect’ by illustrating the cascading effects of EcMF suppression and implicating soil saprotrophic fungi as potential antagonists on bacterial‐EcMF interactions. [ABSTRACT FROM AUTHOR]

Invasive pathogens threaten the sustainability of forest ecosystems globally. Trees possess intrinsic pathogen defence mechanisms, including major gene resistance (MGR) and quantitative disease resistance (QDR). Plant‐symbiotic fungi can enhance tree defences, generating far‐reaching ecosystem impacts. However, the specific contributions of various fungal guilds to this symbiont‐mediated resistance remain unclear. In this study, we inoculated six Pinus monticola seedling families exhibiting resistance (MGR or QDR) or high susceptibility to the introduced invasive pathogen Cronartium ribicola, the causative agent of white pine blister rust (WPBR), with endophytic and ectomycorrhizal fungi, either alone or in combination (symbiont treatments), in an open‐air greenhouse study. Over a period of 25 months, we monitored the growth, foliar terpene defences, and disease progression in trees before and after C. ribicola infection and in trees inoculated with the symbionts but never inoculated with C. ribicola. We observed enhanced inducible host defences and evidence of defensive priming in response to symbiont treatments. In WPBR‐free control treatments, differences in pine defences coincided with an increased seedling growth rate. For WPBR‐infected seedlings, symbiont treatments reduced disease symptoms in seedlings with QDR and to a lesser extent in susceptible families, but not in those with MGR. Furthermore, disease symptoms correlated with variations in terpene composition. Synthesis and applications: Interactions with fungal symbionts should be considered when breeding native trees for resistance against invasive pathogens. Our study underscores the capacity of endophytic and ectomycorrhizal fungi to enhance tree growth and defence while also reducing disease symptoms. We also show that fungi can induce long‐lasting changes in conifer foliar terpenes, suggesting potential applications in tree protection from invasive pathogens. [ABSTRACT FROM AUTHOR]

Fires in coniferous forests throughout the northern United States alter ecosystem processes and ecological communities, including the diversity and composition of microbial communities living in the soil. In addition to its influence on ecosystem processes and functions, the soil microbiome can interact with soilborne pathogens to facilitate or suppress plant disease development. Altering the microbiome composition to promote taxa that inhibit pathogenic activity has been suggested as a management strategy for forest diseases, including Armillaria root disease caused by Armillaria solidipes, which causes growth loss and mortality of conifers. These forest ecosystems are experiencing increased wildfire burn severity that could influence A. solidipes activity and interactions of the soil microbiome with Armillaria root disease. In this research, we examine changes to the soil microbiome following three levels of burn severity in a coniferous forest in northern Idaho, United States, where Armillaria root disease is prevalent. We further determine how these changes correspond to the soil microbiomes associated with the pathogen A. solidipes, and a putatively beneficial species, A. altimontana. At 15-months post-fire, we found significant differences in richness and diversity between bacterial communities associated with unburned and burned areas, yet no significant changes to these metrics were found in fungal communities following fire. However, both bacterial and fungal communities showed compositional changes associated with burn severity, including microbial taxa with altered relative abundance. Further, significant differences in the relative abundance of certain microbial taxa in communities associated with the three burn severity levels overlapped with taxa associated with various Armillaria spp. Following severe burn, we observed a decreased relative abundance of beneficial ectomycorrhizal fungi associated with the microbial communities of A. altimontana, which may contribute to the antagonistic activity of this soil microbial community. Additionally, A. solidipes and associated microbial taxa were found to dominate following high-severity burns, suggesting that severe fires provide suitable environmental conditions for these species. Overall, our results suggest that shifts in the soil microbiome and an associated increase in the activity of A. solidipes following high-severity burns in similar conifer forests may result in priority areas for monitoring and proactive management of Armillaria root disease. IMPORTANCE With its influence on ecosystem processes and functions, the soil microbiome can interact with soilborne pathogens to facilitate or suppress plant disease development. These forest ecosystems are experiencing increased wildfire frequency and burn severity that could influence the fungal root pathogen, Armillaria solidipes, and interactions with the soil microbiome. We examined changes to the soil microbiome following three levels of burn severity, and examined how these changes correspond with A. solidipes, and a putatively beneficial species, A. altimontana. Following severe burn, there was a decreased relative abundance of ectomycorrhizal fungi associated A. altimontana. A. solidipes and associated microbial taxa dominated following highseverity burns, suggesting that severe fires provide suitable environmental conditions for these species. Our results suggest that shifts in the soil microbiome and an associated increase in the activity of A. solidipes following high-severity burns in conifer forests may result in priority areas for monitoring and proactive management of Armillaria root disease. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal fungi in the genus Tuber form hypogeous fruiting bodies called truffles. Many Tuber species are highly prized due to their edible and aromatic ascomata. Historically, there has been attention on cultivating and selling European truffle species, but there is growing interest in cultivating, wild-harvesting, and selling species of truffles endemic to North America. North America has many endemic Tuber species that remain undescribed, including some that have favorable culinary qualities. Here, we describe two such Tuber species from eastern North America. Maximum likelihood and Bayesian phylogenetic analyses of ITS (internal transcribed spacer), tef1 (translation elongation factor 1-alpha), and rpb2 (second largest subunit of RNA polymerase II) sequences were used to place these species within a phylogenetic context. We coupled these data with morphological analyses and volatile analyses based on gas chromatography–mass spectrometry. Tuber cumberlandense, sp. nov. (previously referred to as Tuber sp. 66), is a member of the Rufum clade that has been opportunistically harvested for commercial sale from T. melanosporum orchards across eastern North America. Tuber canirevelatum, sp. nov. belongs in the Macrosporum clade and thus far is only known from eastern Tennessee, USA. Both new species were discovered with the assistance of trained truffle dogs. The volatile profiles of T. canirevelatum and T. cumberlandense were measured in order to characterize aromas based on the chemical compounds produced by these fungi. Ascomata from both species were enriched in acetone, dimethyl sulfide, 1-(methylthio)-1-propene, and 1-(methylthio)propane. In this work, we celebrate and encourage the use of trained truffle-hunting dogs for fungal biodiversity discovery and research. [ABSTRACT FROM AUTHOR]

Stipitate Thelephorales are basidiomycetous, mostly hydnoid, ectomycorrhizal fungi. Some species have declined considerably, and some are threat-listed as vulnerable or endangered. These ecological concerns require a well-resolved taxonomy to understand diversity in this group of fungi and facilitate conservation. However, phylogenetic studies have mostly neglected Southern Hemisphere representatives. This study examines the fleshy species of stipitate Thelephorales from native forests in Australia and New Zealand, using morphological analyses and phylogenetic analyses of nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS barcode) and D1–D2 domains at the 5′ end of nuc 28S rDNA (28S) sequences amplified from DNA isolated from fungarium collections and environmental DNA (eDNA) sequences from the Australian Microbiome initiative. Five new species, Sarcodon austrofibulatus, Hydnellum gatesiae, H. nothofagacearum, H. pseudoioeides, and H. variisporum, are described, Sarcodon carbonarius is transferred to Neosarcodon, and a key is provided for the six named species in the region. Boletopsis and Neosarcodon are reported from Australia for the first time based on detections from eDNA in soil samples taken from native forests. The Australasian species of Hydnellum occupy a highly derived position with the phylogeny of the genus, the members of which are otherwise all from the Northern Hemisphere, suggestive of a long-distance dispersal origin for the Australasian species. [ABSTRACT FROM AUTHOR]

Despite the importance of fungi to forest carbon (C) cycling and increasing calls to include microbial interactions in ecosystem models, how shifting fungal guild abundances impact soil C stocks remains poorly quantified, particularly in mineral soils where most C is stored. Additionally, a greater understanding of how fungal interguild interactions affect belowground litter decomposition is needed to more fully characterize soil C dynamics. To address these knowledge gaps, we conducted a multi-year soil trenching experiment in two temperate Pinus strobus stands in Minnesota, USA. We found that after two years, trenching increased ectomycorrhizal fungal relative abundance while decreasing saprotrophic fungal relative abundance (decreased ectomycorrhizal/saprotrophic ratio) and concurrently decreased soil C stocks by 10%. The decreased C stocks were primarily due to changes in particulate organic matter and were largely constrained to the top 5 cm of the soil. Trenching also stimulated both root and fungal litter decomposition in surface soils. Together, these results support the often proposed but rarely tested hypothesis that shifting fungal guild abundances promote soil C accumulation. However, they also suggest this effect may be most relevant for short-term C storage in upper soil layers. [ABSTRACT FROM AUTHOR]

Background: Interactions between plants and diverse root-associated fungi are essential drivers of forest ecosystem dynamics. The symbiosis is potentially dependent on multiple ecological factors/processes such as host/symbiont specificity, background soil microbiome, inter-root dispersal of symbionts, and fungus–fungus interactions within roots. Nonetheless, it has remained a major challenge to reveal the mechanisms by which those multiple factors/processes determine the assembly of root-associated fungal communities. Based on the framework of joint species distribution modeling, we examined 1,615 root-tips samples collected in a cool-temperate forest to reveal how root-associated fungal community structure was collectively formed through filtering by host plants, associations with background soil fungi, spatial autocorrelation, and symbiont–symbiont interactions. In addition, to detect fungi that drive the assembly of the entire root-associated fungal community, we inferred networks of direct fungus–fungus associations by a statistical modeling that could account for implicit environmental effects. Results: The fine-scale community structure of root-associated fungi were best explained by the statistical model including the four ecological factors/processes. Meanwhile, among partial models, those including background soil fungal community structure and within-root fungus–fungus interactions showed the highest performance. When fine-root distributions were examined, ectomycorrhizal fungi tended to show stronger associations with background soil community structure and spatially autocorrelated patterns than other fungal guilds. In contrast, the distributions of root-endophytic fungi were inferred to depend greatly on fungus–fungus interactions. An additional statistical analysis further suggested that some endophytic fungi, such as Phialocephala and Leptodontidium, were placed at the core positions within the web of direct associations with other root-associated fungi. Conclusion: By applying emerging statistical frameworks to intensive datasets of root-associated fungal communities, we demonstrated background soil fungal community structure and fungus–fungus associations within roots, as well as filtering by host plants and spatial autocorrelation in ecological processes, could collectively drive the assembly of root-associated fungi. We also found that basic assembly rules could differ between mycorrhizal and endophytic fungi, both of which were major components of forest ecosystems. Consequently, knowledge of how multiple ecological factors/processes differentially drive the assembly of multiple fungal guilds is indispensable for comprehensively understanding the mechanisms by which terrestrial ecosystem dynamics are organized by plant–fungal symbiosis. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal (ECM) fungi are important tree symbionts within forests. The biogeography of ECM fungi remains to be investigated because it is challenging to observe and identify species. Because most ECM plant taxa have a Holarctic distribution, it is difficult to evaluate the extent to which host preference restricts the global distribution of ECM fungi. To address this issue, we aimed to assess whether host preference enhances the endemism of ECM fungi that inhabit dipterocarp rainforests. Highly similar sequences of 175 operational taxonomic units (OTUs) for ECM fungi that were obtained from Lambir Hill's National Park, Sarawak, Malaysia, were searched for in a nucleotide sequence database. Using a two‐step binomial model, the probability of presence for the query OTUs and the registration rate of barcode sequences in each country were simultaneously estimated. The results revealed that the probability of presence in the respective countries increased with increasing species richness of Dipterocarpaceae and decreasing geographical distance from the study site (i.e. Lambir). Furthermore, most of the ECM fungi were shown to be endemic to Malaysia and neighbouring countries. These findings suggest that not only dispersal limitation but also host preference are responsible for the high endemism of ECM fungi in dipterocarp rainforests. Moreover, host preference likely determines the areas where ECM fungi potentially expand and dispersal limitation creates distance–decay patterns within suitable habitats. Although host preference has received less attention than dispersal limitation, our findings support that host preference has a profound influence on the global distribution of ECM fungi. [ABSTRACT FROM AUTHOR]

Aim: We used two fungal data sources for occurrence records (fruitbodies and roots) to (1) test the influence of data source on estimating the environmental niche of ectomycorrhizal (ECM) fungi and (2) compare the differences in estimated niche area and density for ECM fungal species with conspicuous (easily observed, i.e. mushrooms) versus inconspicuous (difficult to observe and/or usually overlooked, i.e. crusts and truffles) fruitbodies. Location: Europe. Taxon: Sixty‐six ectomycorrhizal fungi. Methods: We used fungal records obtained from fruitbody and root data of 66 common ECM fungal species in European forests to estimate their environmental niches. The fruitbody data were extracted from public databases (GBIF, UNITE), while the root data (from individual ectomycorrhizas) were obtained from a dataset of 136 ICP Forests long‐term intensive monitoring plots. We estimated the niches for combined data sources (fruitbody and root data) and for each individual data source using six key environmental variables for ECM fungal community composition. We then examined how estimated niche overlap and area (number of cells in niche grid) varied for the two data sources between conspicuous and inconspicuous species. Results: We found that although the niches estimated using combined data from the two data sources had high overlap with the niches estimated from fruitbody data, the niches estimated from fruitbody data had low or medium overlap with the niches estimated using root data for most ECM fungi. The overlap between the two data sources for conspicuous species was significantly larger than that for inconspicuous species. Root data were important for estimating the niche of inconspicuous species, which had a high ratio of root data to fruitbody data. Main Conclusion: Our results indicate that although fruitbody data suffice for estimating the environmental niche for most conspicuous ECM fungi, combined datasets including fruitbody and root data can improve the accuracy of estimated niches and should be used. Root data for inconspicuous species are particularly useful, and thus, adopting root data in niche estimation will better infer the niches of ECM fungi. Inferring niches along environmental variables can guide future sampling and conservation of fungi. [ABSTRACT FROM AUTHOR]

Biotic factors in fungal exudates impact plant-fungal symbioses establishment. Mutualistic ectomycorrhizal fungi play various ecological roles in forest soils by interacting with trees. Despite progress in understanding secreted fungal signals, dynamics of signal production in situ before or during direct host root contact remain unclear. We need to better understand how variability in intra-species fungal signaling at these stages impacts symbiosis with host tissues. Using the ECM model Pisolithus microcarpus , we selected two isolates (Si9 and Si14) with different abilities to colonize Eucalyptus grandis roots. Hypothesizing that distinct early signalling and metabolite profiles between these isolates would influence colonization and symbiosis, we used microdialysis to non-destructively collect secreted metabolites from either the fungus, host, or both, capturing the dynamic interplay of pre-symbiotic signalling over 48 hours. Our findings revealed significant differences in metabolite profiles between Si9 and Si14, grown alone or with a host root. Si9, with lower colonization efficiency than Si14, secreted a more diverse range of compounds, including lipids, oligopeptides, and carboxylic acids. In contrast, Si14's secretions, similar to the host's, included more aminoglycosides. This study emphasizes the importance of intra-specific metabolomic diversity in ectomycorrhizal fungi, suggesting that early metabolite secretion is crucial for establishing successful mutualistic relationships. • Microdialysis was used to sample secreted metabolites non-destructively in situ • Two isolates of Pisolithus microcarpus has contrasting host colonization ability • The two isolates had significantly different metabolite profiles under axenic state • The isolate with lower root colonization produced a more diverse array of compounds • Metabolites from the isolate with higher colonization efficiency mirrored the host [ABSTRACT FROM AUTHOR]

Pecans (Carya illinoinensis), one of the most valuable native North American nut crops, are commonly propagated through grafting to preserve the desired characteristics from parent trees. Since successful cultivation of pecan trees relies on the interplay among scion varieties, rootstocks, and soil conditions, this study investigated the microbial change to communities in the soils and roots of southern (87MX5-1.7) and northern (Peruque) rootstocks in a rootstock test orchard. Both grafted with the 'Pawnee' scion cultivar. Bacterial 16S ribosomal RNA and fungal ITS were amplified from both roots and rhizosphere soils of the two 10-yeargrafted trees, then sequenced and annotated into trophic and nutrient-related groups to characterize the rhizosphere microbiota. The Peruque roots had a higher relative abundance of saprotroph fungi, while 87MX5-1.7 exhibited higher levels of symbiotroph fungi and nitrogen fixation-related bacteria. Among them, the presence of symbiotroph fungi, particularly ectomycorrhizal fungi, notably differed between these two rootstocks, with a significantly higher presence observed in the root of 87MX5-1.7 compared to Peruque. This variation likely leads to divergent pathways of nutrient translocation: Peruque was in favor of multiple fungi (Russula and Inocybe) to gain nutrition, while 87MX5-1.7 preferred a specific domain of fungi (Tuber) and nitrogen fixation-related bacteria (Bradyrhizobia) to form beneficial symbiosis. Moreover, the presence of pathogens suggested a potential risk of Fusarium patch and snow molds in 87MX5-1.7, while canker and black foot disease pose threats in Peruque. The findings of this study suggest that rootstocks from different origins shape rhizosphere microbes differently, potentially affecting nutrient uptake and nut yield. Exploring rootstock-microbe combinations could provide insights into optimizing scion growth and ultimately increasing nut yield. By understanding how different rootstock-microbe interactions influence pecan tree development, growers can strategically select combinations that promote beneficial symbiotic relationships, enhancing nutrient uptake, disease resistance, and overall tree vigor. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal fungi (EMF) are key symbiotic microbial components for the growth and health of trees in urban greenspace habitats (UGSHs). However, the current understanding of EMF diversity in UGSHs remains poor. Therefore, in this study, using morphological classification and molecular identification, we aimed to investigate EMF diversity in three EMF host plants: Cedrus deodara in the roadside green belt, and C. deodara, Pinus massoniana, and Salix babylonica in the park roadside green belt, in Guiyang, China. A total of 62 EMF Operational Taxonomic Units (OTUs) were identified, including 13 EMF OTUs in the C. deodara roadside green belt, and 23, 31, and 9 EMF OTUs in the park green belts. C. deodara, P. massoniana, and S. babylonica were respectively identified in park green belts. Ascomycota and Basidiomycota were the dominant phylum in the EMF communities in roadside and park green habitat, respectively. The Shannon and Simpson indexes of the C. deodara EMF community in the park green belt were higher than those in the roadside green belt. EMF diversity of the tree species in the park green belt was P. massoniana > C. deodara > S. babylonica. Differences in EMF community diversity was observed among the different greening tree species in the UGSHs. UGSHs with different disturbance gradients had a significant impact on the EMF diversity of the same greening tree species. These results can be used as a scientific reference for optimizing the design and scientific management of UGSHs. [ABSTRACT FROM AUTHOR]

Highlights: Urban trees in urban environments are commonly exposed to stresses, contributing to their health decline; Ectomycorrhizal fungi improve the vigour and resilience of Tilia seedlings, but their performance is dependent on soil pH. Inoculation promotes growth in height, biomass production, mycorrhization status, nutrient uptake, and proline accumulation, and these effects dependent on fungi species and soil pH; Inoculation with EcM can be a strategy to produce healthier saplings that when transplanted to the urban environment will have a better performance. Colonization by Ectomycorrhizal (EcM) fungi is key for the health and performance of plants under different stress scenarios, such as those faced by trees in urban environments. Because urban environments can be lacking EcM fungi, we here assessed the benefits of inoculating Tilia tomentosa seedlings in a pre-transplantation nursery context with the EcM fungi Lactarius deliciosus and Paxillus involutus, using substrates of different pH and facing water-stress. P. involutus had a more evident positive effect in T. tomentosa seedlings and had a good performance in both acidic and alkaline substrate. In acidic substrate the fungus increased the plant height by 0.91-fold, increased the mycorrhization rate by 3.23-fold, expansion rate by 5.03-fold and formation of secondary roots by 0.46-fold, compared to the non-inoculated control. This species also improved the phosphorus content of leaves, which revealed a promotion of nutrient uptake. In alkaline substrate P. involutus increased root dry weight by 3.92-fold and the mycorrhization parameters. In contrast, L. deliciosus only had a positive effect in the improvement of mycorrhization and expansion rates and phosphorus content in the root, effects visible only in alkaline substrate. When exposed to water-stress the increase of proline content was visible in acidic substrate for both fungi, L. deliciosus and P. involutus, and in alkaline substrate for the fungus P. involutus, a response indicative of the enhancement of defenses in stressing scenarios such as water scarcity. We conclude that fungal inoculation improves the vigour and resilience of Tilia seedlings and that it is of utmost importance to select a suitable EcM fungus and to consider the soil pH of the transplanting site. The inoculation approach can be a valuable tool to produce robust seedlings which may have a better performance when transplanted to the challenging urban environment. [ABSTRACT FROM AUTHOR]

Introduction: The crown clade is one of two major groups in the Russula subg. Russula. Methods/material: An analysis of Chinese samples was performed based on the morphology, internal transcribed spacer (ITS) sequences, and multi-gene phylogenies of 28S nrLSU, 16S mtSSU, rpb1, rpb2, and tef1-a. Results: The results supported the independence of six new species: Russula alboflava (sect. Amethystinae), R. chrysantha (subsect. Chamaeleontinae), R. liyui (subsect. Laricinae), R. lutescens (subsect. Olivaceinae), R. paraxerampelina, and R. prunicolor (subsect. Xerampelinae) from Fagaceae forest habitats. Subsect. Alboflavinae was newly proposed in sect. Amethystinae. Members of the new subsection include R. alboflava, R. burlinghamiae, and possibly R. ballouii. Discussion: Our analyses also supported the claim that two species of R. fulvograminea (subsect. Laricinae) and R. subrubens (subsect. Xerampelinae) have a Eurasian distribution. The habitat and primary hosts of the main phylogenetic clades within related subsections were summarized and discussed. [ABSTRACT FROM AUTHOR]

Subantarctic Nothofagus forests are the southernmost forests in the world, with negligible atmospheric nitrogen (N) deposition. Most paradigms about the role of ectomycorrhizal (ECM) fungi in N cycling and plant N uptake at high latitudes have been tested in boreal coniferous forests, while in the southern hemisphere, ECM hosts are primarily angiosperms. Using ITS1 meta‐barcoding, we characterized ECM and saprotrophic fungal communities in evergreen and deciduous Nothofagus forests forming monodominant and mixed stands in the archipelago of Tierra del Fuego (Chile and Argentina). We assessed the N economy of Nothofagus by correlating host species with fungal relative abundances, edaphic variables, net N mineralization, microbial biomass N and the activity of eight extracellular soil enzymes activities. The N economy of deciduous N. pumilio forests was strikingly similar to boreal coniferous forests, with the lowest inorganic N availability and net N mineralization, in correlation to higher relative abundances of ECM fungi with enzymatic capacity for organic N mobilization (genus Cortinarius). In contrast, the N economy of evergreen N. betuloides forests was predominantly inorganic and correlated with ECM lineages from the family Clavulinaceae, in acidic soils with poor drainage. Grassy understory vegetation in deciduous N. antarctica forests likely promoted saprotrophic fungi (i.e., genus Mortierella) in correlation with higher activities of carbon‐degrading enzymes. Differences between Nothofagus hosts did not persist in mixed forests, illustrating the range of soil fertility of these ECM angiosperms and the underlying effects of soil and climate on Nothofagus distribution and N cycling in southern Patagonia. [ABSTRACT FROM AUTHOR]

Litter decomposition is a crucial biochemical process regulated by microbial activities in the forest ecosystem. However, the dynamic response of the fungal community during litter decomposition to vegetation changes is not well understood. Here, we investigated the litter decomposition rate, extracellular enzyme activities, fungal community, and nutrient cycling-related genes in leaf and twig litters over a three-year decomposition period in a pure Liquidamabar formosana forest and a mixed L. formosana/Pinus thunbergii forest. The result showed that during the three-year decomposition, twig litter in the mixed forest decomposed faster than that in the pure forest. In both leaf litter and twig litter, β-cellobiosidase and N-acetyl-glucosamidase exhibited higher activities in the mixed forest, whereas phosphatase, β-glucosidase, and β-xylosidase were higher in the pure forest. The fungal α-diversity were higher in both litters in the pure forest compared to the mixed forest, with leaf litter showing higher α-diversity than twig litter. Fungal species richness and α-diversity within leaf litter increased as decomposition progressed. Within leaf litter, Basidiomycota dominated in the mixed forest, while Ascomycota dominated in the pure forest. Funguild analysis revealed that Symbiotroph and ectomycorrhizal fungi were more abundant in the mixed forest compared to the pure forest. In the third-year decomposition, genes related to phosphorus cycling were most abundant in both forests, with the pure forest having a higher abundance of cex and gcd genes. Fungal community structure, predicted functional structure, and gene composition differed between the two forest types and between the two litter types. Notably, the fungal functional community structure during the first-year decomposition was distinct from that in the subsequent two years. These findings suggest that dominant tree species, litter quality, and decomposition time all significantly influence litter decomposition by attracting different fungal communities, thereby affecting the entire decomposition process. [ABSTRACT FROM AUTHOR]

A new species of Pseudosperma is described based on collections recently made in Benin in West Africa. Pseudosperma brunneopilosum sp. nov. occurs in forests dominated by ectomycorrhizal Fabaceae Isoberlinia and Phyllanthaceae Uapaca trees. Phylogenetic analysis of combined ITS‐LSU‐RPB2‐TEF1 gene regions shows that P. brunneopilosum is unrelated and distinct from several recently described species of Pseudosperma also from West Africa. Complete descriptions and illustrations, including photographs and line drawings are presented. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal (ECM) fungi play a major role in forest ecosystems and managed tree plantations. Particularly, they facilitate mineral weathering and nutrient transfer towards colonized roots. Among nutrients provided by these fungi, potassium (K) has been understudied compared to phosphorus (P) or nitrogen (N). The ECM fungus Paxillus ammoniavirescens is a generalist species that interacts with the root of many trees and can directly transfer K to them, including loblolly pine. However, the forms of K that ECM fungi can store is still unknown. Here, we used synchrotron potassium X-ray fluorescence (XRF) and K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy on P. ammoniavirescens growing in axenic conditions to investigate the K chemistries accumulating in the center and the edge of the mycelium. We observed that various K forms accumulated in different part of the mycelium, including K-nitrate (KNO 3), K-C-O compounds (such as K-tartrate K 2 (C 4 H 4 O 6) and K-oxalate (K 2 C 2 O 4)), K-S and K-P compounds. Saprotrophic fungi have been shown to excrete carboxylic acids, which in turn play a role in soil mineral weathering. Our finding of several K counter-ions to carboxylic acids may suggest that, besides their direct transfer to colonized roots, K ions can also be involved in the production of compounds necessary for sourcing nutrients from their surrounding environment by ECM fungi. Additionally, this work reveals that XANES spectroscopy can be used to identify the various forms of K accumulating in biological systems. • We use XANES to identify the K chemistries in the ECM fungus Paxillus ammoniavirescens. • Hotspots of various K forms accumulate in the hyphae P. ammoniavirescens. • K-nitrate, K-C-O, K-S, and K-P compounds were found in P. ammoniavirescens hyphae. • K ions can be involved in compounds needed for mineral weathering by ECM fungi. [ABSTRACT FROM AUTHOR]

Terrestrial plants form primarily mutualistic symbiosis with mycorrhizal fungi based on a compatible exchange of solutes between plant and fungal partners. A key attribute of this symbiosis is the acquisition of soil nutrients by the fungus for the benefit of the plant in exchange for a carbon supply to the fungus. The interaction can range from mutualistic to parasitic depending on environmental and physiological contexts. This review considers current knowledge of the functionality of ectomycorrhizal (EM) symbiosis in the mobilisation and acquisition of soil nitrogen (N) in northern hemisphere forest ecosystems, highlighting the functional diversity of the fungi and the variation of symbiotic benefits, including the dynamics of N transfer to the plant. It provides an overview of recent advances in understanding 'mycorrhizal decomposition' for N release from organic or mineral-organic forms. Additionally, it emphasises the taxon-specific traits of EM fungi in soil N uptake. While the effects of EM communities on tree N are likely consistent across different communities regardless of species composition, the sink activities of various fungal taxa for tree carbon and N resources drive the dynamic continuum of mutualistic interactions. We posit that ectomycorrhizas contribute in a species-specific but complementary manner to benefit tree N nutrition. Therefore, alterations in diversity may impact fungal-plant resource exchange and, ultimately, the role of ectomycorrhizas in tree N nutrition. Understanding the dynamics of EM functions along the mutualism-parasitism continuum in forest ecosystems is essential for the effective management of ecosystem restoration and resilience amidst climate change. Key points: • Mycorrhizal symbiosis spans a continuum from invested to appropriated benefits. • Ectomycorrhizal fungal communities exhibit a high functional diversity. • Tree nitrogen nutrition benefits from the diversity of ectomycorrhizal fungi. [ABSTRACT FROM AUTHOR]

Background: Drought constitutes a major abiotic stress factor adversely affecting plant growth and productivity. Plant-microbe symbiotic associations have evolved regulatory mechanisms to adapt to environmental stress conditions. However, the interactive effects of different fungi on host growth and stress tolerance under drought conditions remain unclear. Objective: This study explored the effects of varying polyethylene glycol (PEG6000) concentrations (0%, 15%, 25%, and 35%) on the growth and physiological responses of two ectomycorrhizal fungi (Suillus granulatus (Sg) and Pisolithus tinctorius (Pt)) and two dark septate endophytes (Pleotrichocladium opacum (Po) and Pseudopyrenochaeta sp. (Ps)) isolated from the root system of Pinus tabuliformis. Specifically, the study aimed to evaluate six inoculation treatments, including no inoculation (CK), single inoculations with Sg, Pt, Po, Ps, and a mixed inoculation (Sg: Pt : Po: Ps = 1:1:1:1), on the growth and physiological characteristics of P. tabuliformis seedlings under different water regimes: well-watered at 70% ± 5%, light drought at 50% ± 5%, and severe drought at 30% ± 5% of the maximum field water holding capacity. Results: All four fungi exhibited the capacity to cope with drought stress by enhancing antioxidant activities and regulating osmotic balance. Upon successful root colonization, they increased plant height, shoot biomass, root biomass, total biomass, and mycorrhizal growth response in P. tabuliformis seedlings. Under drought stress conditions, fungal inoculation improved seedling drought resistance by increasing superoxide dismutase and catalase activities, free proline and soluble protein contents, and promoting nitrogen and phosphorus uptake. Notably, mixed inoculation treatments significantly enhanced antioxidant capacity, osmotic adjustment, and nutrient acquisition abilities, leading to superior growth promotion effects under drought stress compared to single inoculation treatments. Conclusion: All four fungi tolerated PEG-induced drought stress, with increased antioxidant enzyme activities and osmotic adjustment substances and they promoted the growth and enhanced drought resistance of P. tabuliformis seedlings. [ABSTRACT FROM AUTHOR]

In order to adapt to the complex ecological environment, plants and soil fungi form a mutually beneficial symbiotic association-mycorrhiza. The establishment of mycorrhiza is based on the nutrient exchange between the plants and fungi. Fungi provide nutrients such as nitrogen and phosphorus sources for plants. In return, plants provide carbon source for fungus growth. The nutrient metabolism and communication between ectomycorrhizal fungi and symbiotic plants is a research hotspot at home and abroad. The article mainly summarized the research progress of ectomycorrhizal fungi nitrogen cycle at home and abroad and described the uptake of nitrogen sources in soil by ectomycorrhizal fungi and the interaction mechanism with plants. The article also listed the proven compounds and enzymes in the nitrogen cycle pathway of ectomycorrhizal fungi. The article looked forward to future research directions and discusses in depth the mutual nutrition and information exchange between ectomycorrhizal fungi and symbiotic plants. [ABSTRACT FROM AUTHOR]

Tuber aestivum, commonly known as the summer truffle, is typically found in various parts of Europe where it grows naturally. However, its presence in Portugal was not confirmed until now. The first fruit bodies were collected in April 2024 at stone pine stands (Alenquer and Arruda dos Vinhos, Lisbon) and in June at holm oak stands (Salir, Faro). These specimens are characterized by hypogeous, subglobose, black ascomata with a peridium surface covered with pyramidal warts. Ascopores are subglobose-to-broadly ellipsoid, distinctively ornamented, usually 1–6 per asci. According to the results of the internal transcribed spacer (ITS) rDNA sequence analysis, these specimens form a well-supported group within the Aestivum clade, with T. aestivum being the closest phylogenetic taxon. This remarkable discovery opens up new opportunities for truffle exploitation in Portugal thanks to the summer truffle's gastronomical value and high market prices. [ABSTRACT FROM AUTHOR]

Zinc (Zn) is a major soil contaminant and high Zn levels can disrupt growth, survival, and reproduction of fungi. Some fungal species evolved Zn tolerance through cell processes mitigating Zn toxicity, although the genes and detailed mechanisms underlying mycorrhizal fungal Zn tolerance remain unexplored. To fill this gap in knowledge, we investigated the gene expression of Zn tolerance in the ectomycorrhizal fungus Suillus luteus. We found that Zn tolerance in this species is mainly a constitutive trait that can also be environmentally dependent. Zinc tolerance in S. luteus is associated with differences in the expression of genes involved in metal exclusion and immobilization, as well as recognition and mitigation of metal-induced oxidative stress. Differentially expressed genes were predicted to be involved in transmembrane transport, metal chelation, oxidoreductase activity, and signal transduction. Some of these genes were previously reported as candidates for S. luteus Zn tolerance, while others are reported here for the first time. Our results contribute to understanding the mechanisms of fungal metal tolerance and pave the way for further research on the role of fungal metal tolerance in mycorrhizal associations. [ABSTRACT FROM AUTHOR]

Suillus is one of the most important genera of ectomycorrhizal fungi. As a model for studying host specificity, its molecular fragments and nuclear genome have been analyzed. However, its mitochondrial genome has not yet been reported. In this study, we assembled five mitogenomes of Suillus and analyzed and compared their basic characteristics. Owing to the large number of introns as well as intergenic regions, the mitogenomic lengths of species of Suillus were greater than those of other species of Boletales. We identified two main patterns of gene order arrangement in the members of the order Boletales. The Ka/Ks values of 15 protein-coding genes were <1 for the mitochondrial genes of 39 Boletales species, indicating their conserved evolution. Phylogenetic trees, reconstructed using the mitogenomes, indicated that the genus Suillus was monophyletic. Phylogenetic results based on the internal transcribed spacer region and mitogenome were used to confirm the distribution of Suillus placidus in China. The results showed that the mitogenome was superior in distinguishing species compared with a single molecular fragment. This is the first study to investigate the mitogenome of Suillus, enriching the mitogenome information and providing basic data for the phylogeny, resource conservation, and genetic diversity of this genus. [ABSTRACT FROM AUTHOR]

The Brazilian pepper tree (Schinus terebinthifolius) is an invasive species that requires significant disturbance to eradicate. Previous studies have identified associations between the Brazilian pepper tree and ectomycorrhizal fungi (EMF). However, limited research has explored the connection between disturbance from removal and the effect on EMF. This study investigated the sensitivity of EMF and the broader fungal community to the full and selective removal of the Brazilian pepper tree. During the selective removal of Brazilian pepper tree, we examined the mycorrhizal community of the Arroyo willow (Salix lasiolepis) to assess the influence of the restoration disturbance on native species. We used ITS2 sequencing to identify the EMF present during the restoration. Our expectation was that both removal efforts would reduce the presence of EMF. Contrary to our predictions, full removal increased EMF richness and relative abundance in the soil. As anticipated, selective removal reduced the richness and relative abundance of EMF associated with soil. Selective removal led to a decrease in the richness of EMF in arroyo willow roots with no effect on relative abundance. Moreover, fungal community composition in soil and roots shifted significantly during selective and full removal. However, the community composition of EMF, specifically, remained constant across treatment types. During full removal efforts, the application of organic soil amendments may have contributed to the increase in the diversity and relative abundance of EMF. Selective removal will require additional measures, such as soil amendments, to curtail the loss of EMF. [ABSTRACT FROM AUTHOR]

Species of the ectomycorrhizal (ECM) family Cortinariaceae (Agaricales, Agaricomycetes, Basidiomycota) have long been considered impoverished or absent from lowland tropical rainforests. Several decades of collecting in forests dominated by ECM trees in South America's Guiana Shield is countering this view, with discovery of numerous Cortinariaceae species. To date, ~12 morphospecies of this family have been found in the central Pakaraima Mountains of Guyana. Here, we describe three of these as new species of Cortinarius and two as new species of Phlegmacium from forests dominated by the ECM tree genera Dicymbe (Fabaceae subfam. Detarioideae), Aldina (Fabaceae subfam. Papilionoideae), and Pakaraimaea (Cistaceae). Macromorphological, micromorphological, habitat, and DNA sequence data are provided for each new species. [ABSTRACT FROM AUTHOR]

Summary: Ectomycorrhizal (ECM) fungi distribute tree‐derived carbon (C) via belowground hyphal networks in forest ecosystems. Here, we asked the following: (1) Is C transferred belowground to a neighboring tree retained in fungal structures or transported within the recipient tree? (2) Is the overlap of ectomycorrhizal fungi in mycorrhizal networks related to the amount of belowground C transfer?We used potted sapling pairs of European beech (Fagus sylvatica) and North‐American Douglas‐fir (Pseudotsuga menziesii) for 13CO2 pulse‐labeling. We compared 13C transfer from beech (donor) to either beech or Douglas‐fir (recipient) and identified the ECM species. We measured the 13C enrichment in soil, plant tissues, and ECM fractions of fungal‐containing parts and plant transport tissues.In recipients, only fungal‐containing tissue of ectomycorrhizas was significantly enriched in 13C and not the plant tissue. Douglas‐fir recipients shared on average one ECM species with donors and had a lower 13C enrichment than beech recipients, which shared on average three species with donors.Our results support that recently assimilated C transferred belowground is shared among fungi colonizing tree roots but not among trees. In mixed forests with beech and Douglas‐fir, the links for C movement might be hampered due to low mycorrhizal overlap with consequences for soil C cycling. [ABSTRACT FROM AUTHOR]

In this study, the near-naturalization process of Pinus tabulaeformis plantations in Baxianshan National Nature Reserve was divided into three stages depending on the proportion of P. tabulaeformis present, resulting in the following categories: the P. tabulaeformis forest stage, the mixed forest stage, and the near-natural forest stage. Natural secondary forests were selected as a control. We assessed alterations in the soil's fungal functional structures from three aspects: functional mode, vegetative mode, and growth mode, and their responses to vegetation and soil factors were also explored. The results showed that ectomycorrhizal, saprophytic, and plant pathogen types were dominant in the functional mode, and plant pathogens were most abundant in the P. tabulaeformis forest stage. Meanwhile, ectomycorrhizal fungi were the least abundant in the near-natural forest stage. In the vegetative mode, saprophytic, pathophysiological, and symbiotic types were dominant, and pathophysiological types were the most abundant in the P. tabulaeformis forest stage. In the growth mode, microfungi dominated, and the abundance of clavarioid decreased with near-naturalization. The degree of variation in functional structure in the three dimensions increased with near-naturalization, but the structure of natural secondary forests converged. The species composition of tree layer obviously affected the abundance and functional structure of fungi in the three modes, among which Quercus mongolia and Carpinus hornbeam were the most significant. The soil's pH and nitrate content significantly affected the structure of the functional mode, and the soil's dry matter content and C/N ratio significantly affected the structure of the vegetative mode. In this study, we explored the interaction between the plant community and soil ecological system during the near-naturalization process of plantations in terms of soil fungi functions, further clarifying the role of soil functions in the succession of plant communities and providing a new perspective on the in-depth exploration of ecosystem interactions during the succession of plantations. [ABSTRACT FROM AUTHOR]

Highlights Urban trees in urban environments are commonly exposed to stresses, contributing to their health decline; Ectomycorrhizal fungi improve the vigour and resilience of Tilia seedlings, but their performance is dependent on soil pH. Inoculation promotes growth in height, biomass production, mycorrhization status, nutrient uptake, and proline accumulation, and these effects dependent on fungi species and soil pH; Inoculation with EcM can be a strategy to produce healthier saplings that when transplanted to the urban environment will have a better performance.

Abstract Ectomycorrhizal fungi (EMF) are key symbiotic microbial components for the growth and health of trees in urban greenspace habitats (UGSHs). However, the current understanding of EMF diversity in UGSHs remains poor. Therefore, in this study, using morphological classification and molecular identification, we aimed to investigate EMF diversity in three EMF host plants: Cedrus deodara in the roadside green belt, and C. deodara, Pinus massoniana, and Salix babylonica in the park roadside green belt, in Guiyang, China. A total of 62 EMF Operational Taxonomic Units (OTUs) were identified, including 13 EMF OTUs in the C. deodara roadside green belt, and 23, 31, and 9 EMF OTUs in the park green belts. C. deodara, P. massoniana, and S. babylonica were respectively identified in park green belts. Ascomycota and Basidiomycota were the dominant phylum in the EMF communities in roadside and park green habitat, respectively. The Shannon and Simpson indexes of the C. deodara EMF community in the park green belt were higher than those in the roadside green belt. EMF diversity of the tree species in the park green belt was P. massoniana > C. deodara > S. babylonica. Differences in EMF community diversity was observed among the different greening tree species in the UGSHs. UGSHs with different disturbance gradients had a significant impact on the EMF diversity of the same greening tree species. These results can be used as a scientific reference for optimizing the design and scientific management of UGSHs.

Summary: Forest soils play a pivotal role as global carbon (C) sinks, where the dynamics of soil organic matter (SOM) are significantly influenced by ectomycorrhizal (ECM) fungi. While correlations between ECM fungal community composition and soil C storage have been documented, the underlying mechanisms behind this remain unclear.Here, we conducted controlled experiments using pure cultures growing on naturally complex SOM extracts to test how ECM fungi regulate soil C and nitrogen (N) dynamics in response to varying inorganic N availability, in both monoculture and mixed culture conditions.ECM species dominant in N‐poor soils exhibited superior SOM decay capabilities compared with those prevalent in N‐rich soils. Inorganic N addition alleviated N limitation for ECM species but exacerbated their C limitation, reflected by reduced N compound decomposition and increased C compound decomposition. In mixed cultures without inorganic N supplementation, ECM species with greater SOM decomposition potential facilitated the persistence of less proficient SOM decomposers. Regardless of inorganic N availability, ECM species in mixed cultures demonstrated a preference for C over N, intensifying relatively labile C compound decomposition.This study highlights the complex interactions between ECM species, their nutritional requirements, the nutritional environment of their habitat, and their role in modifying SOM. [ABSTRACT FROM AUTHOR]

Summary: The mutualistic interaction between ectomycorrhizal fungi and trees is characterized by the coordinated exchange of soil nutrients with soluble sugars. Despite the importance of this process, the precise mechanism by which sugars are transported from host roots to colonizing hyphae remains unclear.This study aimed to identify the specific membrane transporters responsible for the unloading of sugars at the symbiotic interface, with a focus on the role of the root Sugars Will Eventually Be Exported Transporter (SWEET) uniporters.Our study used RNA sequencing and quantitative PCR to identify PtaSWEET gene expression in Populus tremula × alba–Laccaria bicolor ectomycorrhizal root tips. Our results suggest that symbiosis‐induced PtaSWEET1c is primarily responsible for transporting glucose and sucrose, as demonstrated by the yeast assays. Moreover, we used a promoter‐YFP reporter to confirm the localization of the PtaSWEET1c expression in cortical cells of ectomycorrhizal rootlets, supporting its major role in supplying glucose at the symbiotic interface. Furthermore, our observations confirmed the localization of PtaSWEET1c‐GFP in the plasma membrane. The inactivation of PtaSWEET1c reduced ectomycorrhizal root formation and 13C translocation to ectomycorrhizal roots.Our findings highlight the crucial role of PtaSWEET1c in facilitating glucose and sucrose transport at the symbiotic interface of Populus–L. bicolor symbiosis. [ABSTRACT FROM AUTHOR]

Summary statement: High solar radiation exacerbated the negative effects of extreme drought on plant growth and fine root traits. Ectomycorrhizae did not compensate for fine roots under drought stress. Fine roots biomass determined the role of ectomycorrhizal fungi, supporting the energy limitation hypothesis. [ABSTRACT FROM AUTHOR]

Species of Pseudosperma (Inocybaceae) are widely distributed from temperate to tropical regions. In this study, we describe and illustrate five new species of Pseudosperma: P. beninense, P. cremeo-ochraceum, P. squarrosofulvum, P. stramineum, and P. tiliae, based on comprehensive analyses of morphological and molecular data derived from specimens collected in Benin (West Africa) and Turkey (Western Eurasia). These new species have been found in forests with Isoberlinia spp. and other ectomycorrhizal tree species in Benin and in association with Tilia platyphyllos in Turkey. The phylogenetic relationships of the new species were inferred through analyses of nuclear rDNA sequences, encompassing the internal transcribed spacer (ITS), 28S rDNA, and RNA polymerase II second largest subunit (RPB2) region. Phylogenetic analyses revealed that P. beninense, P. cremeo-ochraceum, P. squarrosofulvum, and P. stramineum from Benin cluster with species from Australia, China, and India within a clade formed exclusively by species known from the palaeotropics and Australia, whereas P. tiliae from Turkey clustered with P. mediterraneum from Italy. Detailed descriptions are provided, supplemented by illustrations and line drawings of key micromorphological features. In addition, a comparative analysis with morphologically similar and phylogenetically closely related species is presented and discussed in detail. [ABSTRACT FROM AUTHOR]

Tuber aestivum, commonly known as the summer truffle, is typically found in various parts of Europe where it grows naturally. However, its presence in Portugal was not confirmed until now. The first fruit bodies were collected in April 2024 at stone pine stands (Alenquer and Arruda dos Vinhos, Lisbon) and in June at holm oak stands (Salir, Faro). These specimens are characterized by hypogeous, subglobose, black ascomata with a peridium surface covered with pyramidal warts. Ascopores are subglobose-to-broadly ellipsoid, distinctively ornamented, usually 1–6 per asci. According to the results of the internal transcribed spacer (ITS) rDNA sequence analysis, these specimens form a well-supported group within the Aestivum clade, with T. aestivum being the closest phylogenetic taxon. This remarkable discovery opens up new opportunities for truffle exploitation in Portugal thanks to the summer truffle’s gastronomical value and high market prices.

Ectomycorrhizal (ECM) fungi, which can form ectomycorrhiza with plants, are an important link between the above-ground symbiotic plants and the subsurface ecosystems, and many of them are nutritious and delicious food. ECM fungi promote the absorption of mineral nutrients by plants, especially for limiting mineral elements such as phosphorus, thereby improving the growth of plants. It is generally believed that ECM fungi acquire mineral nutrients from soil mainly through their weathering effect on soil minerals that are difficult to degrade, but the weathering process and mechanisms are still not clear. Through field investigation, strain isolation and weathering tests, it is found that many ECM fungi cannot weather minerals by up-regulating the synthesis of small molecular organic acids, showing a weak ability to weather mineral. Particularly, they cannot use phosphorus in apatite independently. Bio-omics studies find that in forest soils, some ECM fungi with weaker weathering ability can promote the dissolution of minerals by enrichment of mineral-weathering bacteria, and absorb dissolved mineral nutrients to supply host plants through their high-affinity ion transport systems. In addition, ECM fungi can enrich special versatile oxalate-degrading bacteria (such as those that have the capability of nitrogen fixation and promoting mycorrhizal formation) to eliminate the inhibitory effect of excess oxalate on mineral weathering and nutrient absorption. It has been confirmed that ECM fungi can regulate the rhizosphere microbial community structure and promote the mutually cooperative relationship among plants, fungi and bacteria to maintain a healthy and sustainable forest ecosystem. This paper reviews the symbiotic strategies of ECM fungi from the perspective of mineral weathering, puts forward new ideas for increasing the biomass of edible fungi in woodlands and promoting the sustainability of woodland ecosystems, and gives an outlook on future research directions in this field.

Two new species of Russula subsect. Cyanoxanthinae, collected from tropical and subtropical regions of China, are proposed based on morphological and multi-gene phylogenetic data. Russula icterina is characterized by its green pileus, lamellae with frequent furcations but without lamellulae, basidiospores ornamented with isolated warts with indistinct and inamyloid suprahilar spots, widely dispersed hymenial cystidia rarely with appendages, terminal cells with attenuated or constricted apexes in the pileipellis, one-celled and fusiform pileocystidia without apices that turn grayish black in sulfovanillin, and presence in low-altitude broad-leaved forests dominated by Castanopsis sclerophylla and Quercus acutissima. Russula purpureobrunnea is characterized by its purplish pink to purplish brown pileus, lamellae mixed with lamellulae some with furcations, basidiospores ornamented with isolated warts, clavate or lageniform hymenial cystidia with capitate or mucronate appendages, metachromatic pileipellis with apically attenuated or constricted terminal cells, one-celled pileocystidia that turn grayish black in sulfovanillin, and presence in Pinus yunnanensis, Keteleeria fortunei, Lithocarpus dealbatus, and Quercus spp. mixed forests. Comprehensive morphological descriptions, illustrations, and comparisons with morphologically and phylogenetically related species are provided. [ABSTRACT FROM AUTHOR]

Introduction: Scleroderma bovista can form symbiotic ectomycorrhizal fungi with hazel roots. The mechanism through which S. bovista promotes hazelnut growth remains unclear. Methods: This study aimed to evaluate the effect of ectomycorrhizal fungus S. bovista on the growth and development of hazel roots and gene expression changes through comparative transcriptome analysis. Results: After inoculation with S. bovista, the fungus symbiotically formed ectomycorrhiza with hazel roots. The fresh weights of the aboveground and underground parts of My treatment (inoculated with S. bovista and formed mycorrhiza) were much higher than those of the control, respectively. The length, project area, surface area, volume, forks, and diameter of the inoculated seedlings root were 1.13 to 2.48 times higher than those of the control. In the paired comparison, 3,265 upregulated and 1,916 downregulated genes were identified. The most significantly enriched Gene Ontology term for the upregulated Differentially Expressed Genes was GO:0005215 (transporter activity). Immunohistochemical analysis suggested that the expression levels of auxin and Auxin Response Factor9 were significantly increased by S. bovista after the formation of mycorrhizal fungi in hazelnut root tips. Discussion: These results indicate that genes related to auxin biosynthesis, transport and signaling, and transport of nutrients may contribute to root development regulation in hazel ectomycorrhiza. [ABSTRACT FROM AUTHOR]

Inbreeding, the mating of individuals that are related through common ancestry, is of central importance in evolutionary and conservation biology due to its impacts on individual fitness and population dynamics. However, while advanced genomic approaches have revolutionised the study of inbreeding in animals, genomic studies of inbreeding are rare in plants and lacking in fungi. We investigated global patterns of inbreeding in the prized edible porcini mushroom Boletus edulis using 225 whole genomes from seven lineages distributed across the northern hemisphere. Genomic inbreeding was quantified using runs of homozygosity (ROHs). We found appreciable variation both among and within lineages, with some individuals having over 20% of their genomes in ROHs. Much of this variation could be explained by a combination of elevation and latitude, and to a lesser extent by predicted habitat suitability during the last glacial maximum. In line with this, the majority of ROHs were short, reflecting ancient common ancestry dating back approximately 200–1700 generations ago, while longer ROHs indicative of recent common ancestry (less than approximately 50 generations ago) were infrequent. Our study reveals the inbreeding legacy of major climatic events in a widely distributed forest mutualist, aligning with prevailing theories and empirical studies of the impacts of historical glaciation events on the dominant forest tree species of the northern hemisphere. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The genus Cortinarius (Agaricales, Basidiomycota) is one of the most species-rich fungal genera, with thousands of species reported. Cortinarius species are important ectomycorrhizal fungi and form associations with many vascular plants globally. Until recently Cortinarius was the single genus of the family Cortinariaceae, despite several attempts to provide a workable, lower-rank hierarchical structure based on subgenera and sections. The first phylogenomic study for this group elevated the old genus Cortinarius to family level and the family was split into ten genera, of which seven were described as new. Here, by careful re-examination of the recently published phylogenomic dataset, we detected extensive gene-tree/species-tree conflicts using both concatenation and multispecies coalescent approaches. Our analyses demonstrate that the Cortinarius phylogeny remains unresolved and the resulting phylogenomic hypotheses suffer from very short and unsupported branches in the backbone. We can confirm monophyly of only four out of ten suggested new genera, leaving uncertain the relationships between each other and the general branching order. Thorough exploration of the tree space demonstrated that the topology on which Cortinarius revised classification relies on does not represent the best phylogenetic hypothesis and should not be used as constrained topology to include additional species. For this reason, we argue that based on available evidence the genus Cortinarius should not (yet) be split. Moreover, considering that phylogenetic uncertainty translates to taxonomic uncertainty, we advise for careful evaluation of phylogenomic datasets before proposing radical taxonomic and nomenclatural changes. [ABSTRACT FROM AUTHOR]

Summary: Decades of studies have demonstrated links between biodiversity and ecosystem functioning, yet the generality of the relationships and the underlying mechanisms remain unclear, especially for forest ecosystems.Using 11 tree‐diversity experiments, we tested tree species richness–community productivity relationships and the role of arbuscular (AM) or ectomycorrhizal (ECM) fungal‐associated tree species in these relationships.Tree species richness had a positive effect on community productivity across experiments, modified by the diversity of tree mycorrhizal associations. In communities with both AM and ECM trees, species richness showed positive effects on community productivity, which could have resulted from complementarity between AM and ECM trees. Moreover, both AM and ECM trees were more productive in mixed communities with both AM and ECM trees than in communities assembled by their own mycorrhizal type of trees. In communities containing only ECM trees, species richness had a significant positive effect on productivity, whereas species richness did not show any significant effects on productivity in communities containing only AM trees.Our study provides novel explanations for variations in diversity–productivity relationships by suggesting that tree–mycorrhiza interactions can shape productivity in mixed‐species forest ecosystems. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal fungi employ different strategies for mycelial growth and host colonization under varying nutrient conditions. However, key genes associated with mycorrhizal interaction should be influenced solely by the inoculation treatment and not by nutrient variations. To utilize subtle nutrient differences and rapidly screen for key genes related to the interaction between Suillus luteus and Pinus massoniana, we performed an inoculation experiment using culture bottles containing high- and low-nutrient media. Interestingly, S. luteus LS88 promoted the growth of P. massoniana seedlings without mature ectomycorrhiza, and the impact of LS88 inoculation on P. massoniana roots was greater than that of nutrient changes. In this study, the resequenced genome of the LS88 strain was utilized for transcriptome analysis of the strain. The analysis indicated that a unique gene encoding glutathione S-transferase (GST) in LS88 is likely involved in colonizing P. massoniana roots. In this study, the GST gene expression was independent of nutrient levels. It was probably induced by P. massoniana and could be used as a marker for S. luteus colonization degree. [ABSTRACT FROM AUTHOR]

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 (Höhn. & Litsch) , Russula densifolia (Secr. ex Gillet) and Tuber nitidum (Vittadini) 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. [ABSTRACT FROM AUTHOR]

Background and aims: Several lines of evidence indicate that arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) associations can have different effects on soil nutrient dynamics. Some lineages of ECM fungi can extract N from organic matter, with varying impacts on decomposers, soil carbon pools, mineral N availability, and plants that lack ECM. However, these effects are not always observed, and it is not clear how they are mediated by environmental factors. Methods: We used Plant Root Simulator probes to compare soil availability of a wide range of nutrients beneath replicated 30-yr old plantations of Chilean Nothofagus (ECM) and Cupressaceae (Austrocedrus, Fitzroya: AM) on a lowland temperate site. Probes were buried for two 8-week periods in early spring and late summer. We also compared understorey composition beneath plantations, to test for evidence of different successional trajectories beneath Nothofagus and Cupressaceae. Results: Soil organic carbon, total N and total phosphorus did not differ significantly between Nothofagus and Cupressaceae stands. Redundancy analysis revealed significant effects of both plantation type (Nothofagus vs. Cupressaceae) and season on overall mineral nutrient availability. Mineral N availability did not differ significantly between Nothofagus and Cupressaceae plots, but pH and calcium availability were significantly lower beneath Nothofagus. Manganese (Mn) was much more available beneath Nothofagus stands, which might reflect abundant Mn-peroxidase, a key enzyme involved in breakdown of lignin by ECM fungi. Understorey composition varied considerably between individual plantations, but did not differ significantly between Nothofagus and Cupressaceae plantations. Conclusions: Despite an overall effect on the stoichiometry of nutrient availability, we found little evidence of modification of the local N cycle by ECM fungi, or of divergent regeneration patterns beneath AM and ECM plantations. This might reflect the relatively N-rich character of this site, and/or mycorrhizal effects being counteracted by leaf trait differences between Chilean Cupressaceae and Nothofagus species. [ABSTRACT FROM AUTHOR]

Differences between arbuscular (AM) and ectomycorrhizal (EcM) trees strongly influence forest ecosystem processes, in part through their impact on saprotrophic fungal communities. Ericoid mycorrhizal (ErM) shrubs likely also impact saprotrophic communities given that they can shape nutrient cycling by slowing decomposition rates and intensifying nitrogen limitation. We investigated the depth distributions of saprotrophic and EcM fungal communities in paired subplots with and without a common understory ErM shrub, mountain laurel (Kalmia latifolia L.), across an AM to EcM tree dominance gradient in a temperate forest by analyzing soils from the organic, upper mineral (0–10 cm), and lower mineral (cumulative depth of 30 cm) horizons. The presence of K. latifolia was strongly associated with the taxonomic and functional composition of saprotrophic and EcM communities. Saprotrophic richness was consistently lower in the Oa horizon when this ErM shrub species was present. However, in AM tree-dominated plots, the presence of the ErM shrub was associated with a higher relative abundance of saprotrophs. Given that EcM trees suppress both the diversity and relative abundance of saprotrophic communities, our results suggest that separate consideration of ErM shrubs and EcM trees may be necessary when assessing the impacts of plant mycorrhizal associations on belowground communities. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal inoculum has emerged as a critical tool for forest restoration, especially under challenging climate change conditions. The inoculation of selective ectomycorrhizal fungi can enhance seedling survival and subsequent growth in the field. This study optimized the liquid media for mycelial growth of Astraeus odoratus strain K1 and the sodium alginate solution composition for enhanced mycelial viability after entrapment. Using Modified Melin-Norkrans as the optimal media for mycelial cultivation and 2% sodium alginate supplemented with Czapek medium, 0.25% activated charcoal, 5% sucrose, and 5% sorbitol in the alginate solution yielded the highest viability of A. odoratus mycelia. Preservation in distilled water and 10% glycerol at 25 °C for 60 days proved to be the most effective storage condition for the alginate beads. Both fresh and preserved alginate beads were tested for colonizing on Hopea odorata Roxb. seedlings, showing successful colonization and ectomycorrhizal root formation, with over 49% colonization. This study fills a crucial gap in biotechnology and ectomycorrhizal inoculum, paving the way for more effective and sustainable forest restoration practices. [ABSTRACT FROM AUTHOR]