Search Results (103)

The success of truffle cultivation is especially dependent on the quality of truffle-mycorrhized seedlings, which are typically produced in nurseries under aseptic conditions to avoid root colonization by undesired ectomycorrhizal fungi. However, such practices may also eliminate beneficial microorganisms that could support truffle symbiosis and improve seedling quality. In this study, twelve endophytic bacterial and fungal strains, isolated from the Tuber melanosporum environment (gleba tissue, mycorrhizae and truffle brûlé), were tested for their effect on T. melanosporum mycorrhization levels in inoculated Quercus ilex seedlings under nursery conditions. Co-inoculation with a strain of Agrobacterium tumefaciens significantly enhanced root colonization by T. melanosporum, supporting its potential role as mycorrhizal helper bacterium. In contrast, a strain of Trichoderma harzianum negatively affected mycorrhization. The remaining strains did not show significant effects on seedling mycorrhization or seedling growth. Our findings support the hypothesis that specific bacterial strains associated with truffles can act as mycorrhizal helper bacteria, highlighting the potential for co-inoculation strategies to enhance quality of truffle-inoculated seedlings in nurseries. However, further research is needed to gain a deeper understanding of the interactions within the mycorrhizosphere that could contribute to improving nursery seedling quality. Full article

In order to precisely improve the quality of major tree species in northern China, near-natural differentiated management has been gradually introduced into forestry practice, aiming to optimize forest structure, enhance forest quality, and promote nutrient cycling and water conservation. As an essential element of forest ecosystems, soil microbes contribute to biodiversity preservation and nutrient turnover in soils. This study selected three typical forest types (Quercus acutissima forest, Pinus tabulaeformis forest, and Pinus tabulaeformis × Quercus mixed forest) that have been managed with target trees on Zhongtiao Mountain. Using 16S/ITS rRNA high-throughput sequencing, this study systematically assessed the influences of forest type and soil depth (0–60 cm) on the soil properties and microbial communities. The results showed that the fungal alpha diversity indices were the highest in Pinus tabulaeformis forest, which decreased with soil depth. Actinobacteriota exhibited the greatest relative abundance in mixed forest, whereas Ascomycota predominated in the Pinus tabulaeformis forest. The microbial co-occurrence network exhibited greater complexity compared to the pure forest. Microbial carbon and nitrogen cycling functions showed strong correlation with soil pH and nutrient levels. Symbiotrophs dominated the fungal community, and ectomycorrhizae were significantly abundant in mixed forests. pH is the dominant factor driving changes in microbial communities. In summary, the mixed forest improved soil nutrients, enhanced the complexity of microbial networks, and supported higher ectomycorrhizal abundance. These findings provide practical guidance for improving soil health and stability of forest ecosystems through near-natural management. Full article

Evaluating forest functional indicators is essential for effective forest management planning. In this study, we conducted a metagenome-based comparative analysis of the rhizosphere soils from a natural Quercus mongolica stand and an artificial Larix kaempferi stand on Mt. Gariwang, Pyeongchang, Republic of Korea. Both stands originally belonged to the same natural forest and represent the current dominant tree species. Bacterial communities were affected more by climate than by tree species. A bacterial co-occurrence network analysis showed more complex interactions in the Q. mongolica than in L. kaempferi. Conversely, fungal communities were affected more by tree species than by climate. Specifically, the Q. mongolica stand had a high ratio of saprotrophic fungi, whereas the L. kaempferi stand exhibited a higher ratio of fungi associated with nutrient decomposition and harbored a high proportion of fungi that form ectomycorrhizae with long-distance exploration types. These fungal traits serve as indicators of soil ecological changes in Q. mongolica and L. kaempferi stands. Our comparative analysis of the microbial communities of Q. mongolica and L. kaempferi, representative plantation species in the Republic of Korea, revealed seasonal and host species–specific bacterial and fungal associations, and fungal communities were less variable than bacterial communities and more accurately reflected host tree traits. Full article

Pinus tabuliformis is a well-recognized woody mycorrhizae host plant growing in North China. EM fungi contribute to the host health and the stability of the forest ecosystem. However, ectomycorrhiae (EM) fungal community associated with this species is less documented. In this study, we examined EM fungal diversity and composition of P. tabuliformis from three sites in Inner Mongolia, China by using Illumina MiSeq sequencing on the rDNA ITS2 region. Our results showed that a total of 105 EM fungal operational taxonomic units (OTUs) were identified from 15 composite root samples, and the dominant lineages were /suillus-rhizopogon, /tomentella-thelephora, /tricholoma, /amphinema-tylospora, /wilcoxina, /inocybe, and /Sebacina. A high proportion of unique EM fungal OTUs (33, 31.4% of total OTUs) were detected, and some abundant OTUs preferred to exist in specific sites. The composition of EM fungal communities was significantly different among the sites, with soil, climatic, and spatial variables being related to the community variations. The EM fungal community assembly was mainly driven by environmental factors in deterministic processes. These findings suggest that this endemic Pinaceae species in China also harbored a rich and distinctive EM fungal community and deterministic processes played more important roles than stochastic in shaping the symbiotic fungal community. Our study improves our understanding of EM fungal diversity and community structure from the perspective of a single host plant that has not been investigated exclusively before. Full article

The synthesis and symbiotic mechanisms of truffle ectomycorrhizae have attracted considerable scientific interest in recent decades. Although previous research has successfully identified the symbiotic partners of truffles (Tuber spp.) and characterized their mature morphological features, the dynamic processes involved in truffle ectomycorrhizal formation remain insufficiently understood. In this study, we established an ectomycorrhizal synthesis system using Castanea mollissima seedlings inoculated with Tuber sinense spore suspensions under controlled greenhouse conditions, followed by an eight-month observation period. To systematically characterize and model the morphological changes during ectomycorrhizal development, we employed an innovative approach integrating resin sectioning with confocal microscopy. Ectomycorrhizal formation was initially observed two months post inoculation, with a colonization rate reaching 24.4 ± 5.3% by the third month. The ectomycorrhizae displayed a distinct color progression from light brown through ochre and finally dark brown, typically manifesting either monopodial or branched structures. Early developmental stages (2–3 months) were characterized by a thin mycelial membrane enveloping the root surface, accompanied by limited hyphal penetration into the root system. By the eighth month, the colonization rate stabilized at 45.2 ± 8.6%, with enhanced organization and density of the fungal mantle and extended Hartig nets reaching the periphery of outer cortical cells. The continuous growth and differentiation of mycorrhizal root tips generated repetitive root architectures, significantly enhancing symbiotic efficiency. These findings provide critical insights into the morphological development and symbiotic effectiveness of truffle ectomycorrhizae while establishing a methodological framework for investigating ectomycorrhizal associations in other economically significant plant–fungal systems. Full article

Soil salinization is a growing global concern in many ecosystems. Although ectomycorrhizal fungi have been shown to alleviate the effects of salinity in some tree species, uncertainties persist concerning their effectiveness when plants are exposed to different salinity levels that are commonly present in salt-affected soils. Quercus dentata seedlings either non-inoculated (mycorrhizal control) or inoculated with the ectomycorrhizal fungus Laccaria bicolor were then treated with three NaCl concentrations (0, 0.4%, and 0.8%). The physiological, stoichiometric, and growth characteristics of the plants were examined. NaCl significantly affected seedling growth and physiology. However, the impact of L. bicolor on Q. dentata seedlings could shift in response to varying salt concentrations. Under moderate salinity, inoculation of L. bicolor increased root biomass by 4.55% and leaf chlorophyll concentrations by 46.8%, and decreased leaf Na⁺ concentrations and the Na⁺/K⁺ ratios. Under high salinity, L. bicolor decreased leaf water content and fluorescence parameters, and increased leaf Na⁺ concentrations. The effect of ectomycorrhizal fungus L. bicolor on Q. dentata seedlings was dependent on NaCl concentration, and our results indicate that the use of L. bicolor in afforestation efforts with Q. dentata would only be effective under relatively low soil salinity levels. Full article

Mycorrhizal symbiosis has been the focus of research for more than a century due to the positive effect of fungi on the growth of the majority of woody plants. The extramatrical mycelium (EMM) of ectomycorrhiza (EMR) accounts for up to one-third of the total soil microbial biomass, whereas litter from this short-living pool accounts for 60% of the total litterfall mass in forest ecosystems. The functioning of EMR improves the nitrogen (N) nutrition of trees and thus contributes to the carbon (C) balance of forest soils. The model presented here is an attempt to describe these EMR functions quantitatively. It calculates the growth of EMM and the subsequent “mining” of additional nitrogen from recalcitrant soil organic matter (SOM) for EMR growth, with the associated formation of “dissolved soil carbon”. The decomposition of EMM litter is carried out by all organisms in the soil food webs, forming available ${\mathrm{N}\mathrm{H}}_4^{+}$ in the first phase and then solid-phase by-products (excretes) as a new labile SOM pool. These substances are the feedback that determines the positive role of EMR symbiosis for forest vegetation. A sensitivity analysis revealed a leading role of the C:N ratio of biotic components in the dynamics of EMM. The model validation showed a satisfactory agreement between simulated and observed data in relation to EMM respiration in larch forest plantations of different ages. Model testing within the EFIMOD3 model system allowed a quantitative assessment of the contribution of different components to forest soil and ecosystem respiration. The validation and testing of this model demonstrated the adequacy of the theoretical background used in this model, with a fast EMM decomposition cycle by all soil biota of the food webs and without direct resource exchange between plants and fungi. Full article

Moss–cyanobacteria associations serve as significant nitrogen fixers and represent the primary nitrogen sink in boreal forests. Fungi, which are essential for soil biogeochemical cycling, have community structures intrinsically linked to forest ecosystem health and productivity. Using high-throughput sequencing, we investigated differences between moss-covered and non-moss soils in two alpine forests (both plantation and natural forests) by examining soil nitrogen contents, fungal community structure, composition, and functional guilds. Results demonstrated that moss cover enhanced soil nutrient contents, including total carbon, total nitrogen, and inorganic nitrogen. It also altered fungal community characteristics, resulting in higher Chao1 and Shannon diversity indices, as well as a more complex fungal network. Notable changes in functional guilds included an increase in saprotrophic fungi abundance and a decrease in ectomycorrhizal fungi. Our findings support the concept that moss cover creates distinct soil environments: moss-covered soils attract decomposers and nutrient-mobilizing fungi (particularly saprotrophs and ectomycorrhiza), while non-moss soils favor ectomycorrhizal fungi that relieve nutrient limitation through extensional mycelial networks. These findings highlight the critical role of moss cover in sustaining forest soil health and resilience, positioning it as a cornerstone of carbon and nutrient cycling within forest ecosystems. Full article

The interactive effects of environmental heterogeneity caused by forest gaps and ectomycorrhizae on fungal community characteristics remain insufficiently explored. To address this knowledge gap, we established a three-year field manipulation experiment in a Picea asperata (Picea asperata Mast.) plantation located in the subalpine region of western Sichuan, China. Growth bags with three mesh sizes—1000 μm (allowing ectomycorrhizae and hyphae), 48 μm (excluding ectomycorrhizae), and 1 μm (excluding both)—were placed across forest gaps (closed canopy, gap edge, and gap center) to investigate how gap disturbances influence soil fungal communities via changes in ectomycorrhizal and hyphal turnover alongside soil physicochemical properties. Soil fungal α-diversity was significantly lower under closed-canopy conditions than at forest gap centers and remained unaffected by ectomycorrhizal and hyphal treatments. Particularly, species diversity increased by 9%, and phylogenetic diversity increased by 10% in forest gap centers compared to the closed canopy. In contrast, soil fungal β-diversity responded to both ectomycorrhizal/hyphal treatments (R² = 0.061; p = 0.001) and forest gap positions (R² = 0.033; p = 0.003). Pairwise comparative analyses revealed significant distinctions between treatments, concurrently excluding ectomycorrhizal and hyphal treatments versus other experimental treatments, as well as between closed-canopy conditions and forest gap centers. The fungal community was dominated by four major phyla: Ascomycota (25.6%–71.0%), Basidiomycota (17.7%–43.7%), Mortierellomycota (1.4%–24.5%), and Rozellomycota (0.4%–2.9%), the relative abundances of which were unaffected by either ectomycorrhizal/hyphal treatments or forest gap positions. The biomass of ectomycorrhizal and saprotrophic fungi showed no significant response to ectomycorrhizal/hyphal treatments. Notably, the exclusion of ectomycorrhizae and hyphae enhanced the significant correlations between fungal community characteristics and soil physicochemical properties. Hierarchical partitioning analysis revealed that the soil water content (SWC) and dissolved organic carbon content were the key determinants of soil fungal community characteristics beneath closed-canopy conditions. In contrast, at forest gap edges and centers, the fungal communities were predominantly shaped by the SWC and dissolved carbon and nitrogen contents. This study highlights the impacts of forest gap disturbances and ectomycorrhizal treatments on soil fungal communities, offering valuable insights for the sustainable management and biodiversity conservation of subalpine forest ecosystems. Full article

Calcium (Ca) is an essential plant nutrient and cell signal element, but in the cultivation of container seedlings, the regulatory effect of Ca on seedling nitrogen nutrition and its regulatory mechanism have been neglected. Ectomycorrhizal fungi (ECMF) inoculation is widely used in forest container seedling cultivation. Thus, we added a certain amount of Ca to the culture matrix to determine how the cooperation between Ca and ECMF improves the nitrogen nutrition of Pinus massoniana ectomycorrhizal (ECM) container seedlings. We found that addition Ca significantly increased the relative abundance of Actinomycetota and Bacillota in the rhizosphere of ECM seedlings. These enriched bacteria cooperated with the ECMF and significantly enhanced extracellular enzyme NAG and LAP secretion. Meanwhile, adding Ca promoted the microbial nitrogen cycle in the ECM seedlings rhizosphere, and the relative abundances of nitrogen fixation genes (nifD, nifH, nifK) and the dissimilatory nitrate reduction gene (narH) significantly increased. In addition, Ca promoted the infection of ECMF on seedlings and induced the sprouting of absorptive roots with larger diameter (0.5 mm < RD ≤ 2.0 mm), i.e., ECM seedlings adopted a dual strategy of enhancing mycorrhizal symbiosis and improving root absorption area to obtain soil nitrogen. These effects contributed to an increase in microbial biomass nitrogen (MBN) and seedling nitrogen content by 20.65% and 54.38%, respectively. The results provide an effective method and theoretical reference for improving the quality of container seedlings and increasing the ECM plantations early productivity. Full article

Forest fires represent a significant ecological disturbance in ecosystems that increasingly affects Pinus heldreichii H. Christ forests at the upper tree line in Montenegro, due to climate change and anthropogenic factors. Soil samples were collected from five high-altitude sites in the Kuči Mountains, including three post-fire sites (2-, 4-, and 6-years post-fire) and two unburned control sites. High-throughput sequencing and soil chemical analyses were conducted to assess fungal diversity, community composition, and soil nutrient properties. The results showed that fungal diversity was significantly higher in unburned soils compared to post-fire soils, with the most prominent changes in ectomycorrhizal fungi, which are crucial for pine regeneration. The fungal community composition differed markedly between the post-fire and unburned sites, with specific taxa such as Hygrocybe conica (Schaeff.) P. Kumm. and Solicoccozyma aeria (Saito) Yurkov dominating the post-fire environments. Despite this, the fungal richness did not significantly change over time (2-, 4-, or 6-years post-fire), suggesting the slow recovery of fungal communities in high-altitude environments. In addition to shifts in fungal biodiversity, the post-fire soils exhibited higher levels of available phosphorus, likely due to the conversion of organic phosphorus into soluble forms during combustion. However, the organic matter content remained unchanged. This study provided important insights into the long-term ecological impacts of forest fires on high-altitude P. heldreichii forests and underlined the importance of preserving unburned forest areas to maintain fungal biodiversity and support natural regeneration, as well as the potential need for active restoration strategies in fire-affected regions. Full article

Tricholoma matsutake, a highly valued ectomycorrhizal fungus, requires a symbiotic relationship with pine trees for growth, complicating its cultivation. This study presents a comprehensive comparative genomic analysis of Tricholoma species, with a focus on T. matsutake. Genomic data from 19 assemblies representing 13 species were analyzed to identify genus-, species-, and strain-specific genes, revealing significant evolutionary adaptations. Notably, T. matsutake exhibits a higher proportion of repetitive elements compared to other species, with retrotransposons like LTR Gypsy dominating its genome. Phylogenomic analyses showed that T. matsutake forms a monophyletic group closely related to T. bakamatsutake. Gene family expansion and contraction analyses highlighted the unique evolutionary pressures on T. matsutake, particularly the loss of tryptophan-related metabolic pathways and the gain of genes related to iron ion homeostasis, which may be crucial for its adaptation to nutrient-limited environments. Additionally, the reduction in secreted proteins and carbohydrate-active enzymes reflects the host-dependent lifestyle of T. matsutake and related species. These findings enhance our understanding of the genetic and evolutionary mechanisms underlying the complex symbiotic relationships of T. matsutake, offering potential avenues for optimizing its cultivation and commercial value. Full article

Nanopore raw read accuracy has improved to over 99%, making it a potential tool for metabarcoding. For broad adoption, guidelines on quality filtering are needed to ensure reliable taxonomic unit recovery. This study aims to provide those guidelines for a fungal metabarcoding context and to apply them to a case study of ectomycorrhizae in the decaying bark of Fagus sylvatica. We introduce the eNano pipeline to test two standard metabarcoding approaches: (1) Reference-based mapping leveraging UNITE’s species hypothesis system (SH approach); (2) Constructing 98% OTUs (OTU approach). Our results demonstrate that both approaches are effective with Nanopore data. When using a reference database, we recommend strict mapping criteria rather than Phred-based filtering. Leveraging the SH-system further enhances reproducibility and facilitates cross-study communication. For the 98% OTUs, filtering reads at ≥Q25 is recommended. Our case study reveals that the decay gradient is a primary determinant of community composition and that specific mycorrhizal fungi colonize decaying bark. Complementing our metabarcoding results with root tip morphotypification, we identify Laccaria amethystina and Tomentella sublilacina as key ectomycorrhizae of saplings on decaying logs. These findings demonstrate that Nanopore sequencing can provide valuable ecological insights and support its broader use in fungal metabarcoding as read quality continues to improve. Full article

Tuber aestivum is a key truffle species with significant ecological and economic value. Despite its importance, plantation success can be influenced by soil pH, host plants, and undesired fungi. This study examines how soil pH and host plants influence mycorrhization trends in T. aestivum plantations across six plant species in eight Hungarian settlements, using root sampling and DNA analysis to assess plantations at three and six years of age. Tuber aestivum achieved over 30% mycorrhization, with Carpinus betulus showing the highest levels. DNA analysis identified eight undesired mycorrhizal fungi, with Suillus spp. (42.9%) and Scleroderma spp. (31.4%) being the most prevalent. The study found that T. aestivum preferred a soil pH of around 7.6, while undesired fungi thrived in slightly acidic conditions. Additionally, soil pH significantly and positively influenced T. aestivum mycorrhization; however, factors such as plantation age also contributed to mycorrhization trends. While mycorrhization by undesired fungi decreased with higher soil pH, it increased as plantations matured from three to six years. These findings highlight the need for the effective management of soil pH and the control of undesired fungi to optimize T. aestivum mycorrhization, emphasizing the importance of targeted strategies and further research for sustainable truffle cultivation. Full article

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. Full article