Diversity Of Ectomycorrhizal Fungal Communities Research Articles

Diversity of Ectomycorrhizal Fungal Communities in Four Types of Stands in Pinus massoniana Plantation in the West of China

Ectomycorrhizal (ECM) fungi can form symbioses with plant roots, which play an important role in regulating the rhizosphere microenvironment. As a broad-spectrum ECM tree species, Pinus massoniana forms symbiotic relationship called mycorrhiza with various ECM fungal species. In this study, four types of forests were selected from a 38-year-old Pinus plantation in eastern Sichuan, namely, pure P. massoniana forest (MC), P. massoniana mixed with Cunninghamia lanceolata forest (MS), P. massoniana–Cryptomeria fortunei forest (ML), and P. massoniana–broadleaved forest (MK), the species mixture ratio of all forests was 1:1. The ITS2 segment of ECM root tip sequenced by high-throughput sequencing using the Illumina MiSeq sequencing platform. (1) The ECM fungi of these four P. massoniana forests showed similar dominant genera but different relative abundances in community structure during the three seasons. (2) The alpha diversity index of ECM fungi was significantly influenced by season and forest type. (3) Soil pH, soil organic matter (SOM), total nitrogen (TN), C/N ratio, and total phosphorus (TP) influenced the ECM fungal community structure in different seasons. In summary, there were significant differences in ECM fungal communities among different forest types and different seasons; the colonization rate of ECM fungal in P. massoniana–Cunninghamia lanceolata was the highest, so we infer that Cunninghamia lanceolata is the most suitable tree species for mixed with P. massoniana in three mixture forests.

Fungal diversity in canopy soil of silver beech, Nothofagus menziesii(Nothofagaceae).

Adventitious roots in canopy soils associated with silver beech (Nothofagus menziesii Hook.f. (Nothofagaceae)) form ectomycorrhizal associations. We investigated the extent to which canopy ectomycorrhizal communities contribute to overall diversity of ectomycorrhizal fungi associated with silver beech. Hyphal ingrowth bags were buried for 12 months in canopy and terrestrial soils of five trees at one site. We used amplicon sequencing of the nuclear ribosomal internal transcribed spacer 2 region (ITS2) to assess diversity of both ectomycorrhizal and non-ectomycorrhizal OTUs in hyphal ingrowth bags. There was a significant difference in ectomycorrhizal fungal community diversity between the terrestrial and canopy hyphal ingrowth bag communities. Ectomycorrhizal community composition of the terrestrial and canopy environments was also significantly different. Some ectomycorrhizal taxa were significantly differentially represented in either the terrestrial or canopy environment. The hyphal ingrowth bags also accumulated non-ectomycorrhizal species. The non-ectomycorrhizal fungi also had significantly different diversity and community composition between the canopy and terrestrial environments. Like the ectomycorrhizal community, some non-ectomycorrhizal taxa were significantly differentially represented in either the terrestrial or canopy environment. The canopy soil microhabitat provides a novel environment for growth of ectomycorrhizal adventitious roots and enables the spatial partitioning of ectomycorrhizal and non-ectomycorrhizal fungal diversity in the forest.

Functional diversity of ectomycorrhizal fungal communities along a peatland–forest gradient

Peatlands are valuable wetland ecosystems that are widespread in boreal forest regions. In addition to harboring numerous uniquely adapted species, they play a major role in global climate regulation due to their ability to sequester large amounts of carbon in soil. Despite their significance, however, many aspects of peatland ecology remain largely unknown. Our study aimed to deepen the understanding of one such aspect, namely peatland ectomycorrhizal (ECM) fungal communities. The structure of belowground ECM fungal communities of Scots pine along a peatland – forest ecotone in the Lithuanian Čepkeliai peatland was examined by molecular identification of ectomycorrhizae collected at the study sites. Additionally, the ectomycorrhizae functionality, as expressed by exploration types, was assessed. The results revealed significant differences in the taxonomic composition of ECM fungal communities along the gradient. Moving from peatland to forest, a gradual increase in ECM fungal taxonomic richness was observed. As the soil water content increases, the medium and long distance exploration types of ectomycorrhizae became more prevalent and dominated on the peatland site. To our knowledge, this study is the first to document ECM fungal communities of Scots pine in peatland conditions and in European peatlands more broadly.

Functional diversity of ectomycorrhizal fungal communities is reduced by trace element contamination

Trait-based approaches are useful tools to explain ecological assembly rules and ecosystem functioning. However, their use for soil microbiota has not been explored in depth yet. We explored trait-based functional changes of ectomycorrhizal (ECM) fungal communities associated with holm oak (Quercus ilex subsp. ballota) in a trace element contaminated area.We found a variation in ECM fungal species composition determined by soil C, Ca and trace elements; however, taxonomic diversity was not dependant on contamination level. Mean trait values of ECM fungal communities showed less rhizomorph and emanating hyphae production when increasing contamination, and the community converged towards species developing rhizomorphs less frequently. We suggest that trace elements in soils acted as the main environmental filter of trait diversity of ECM fungal communities. The effect of soil nutrients, i.e. soil C, affected the community mean trait values of emanating hyphae but did not cause a convergence in its distribution.In summary, we found a reduction in the functional diversity of ECM fungal communities due to trace element contamination with potential to affect ecosystem functioning. This finding supports the potential of trait-based approaches to assess changes in the functional diversity of soil microbial communities.

Soil moisture and chemistry influence diversity of ectomycorrhizal fungal communities associating with willow along an hydrologic gradient.

Influences of soil environment and willow host species on ectomycorrhizal fungi communities was studied across an hydrologic gradient in temperate North America. Soil moisture, organic matter and pH strongly predicted changes in fungal community composition. In contrast, increased fungal richness strongly correlated with higher plant-available phosphorus. The 93 willow trees sampled for ectomycorrhizal fungi included seven willow species. Host identity did not influence fungal richness or community composition, nor was there strong evidence of willow host preference for fungal species. Network analysis suggests that these mutualist interaction networks are not significantly nested or modular. Across a strong environmental gradient, fungal abiotic niche determined the fungal species available to associate with host plants within a habitat.

Effects of soil tillage on Tuber magnatum development in natural truffières

Tuber magnatum Pico, the Italian white truffle, commands the highest prices of any truffle. Despite its commercial value, it is the only edible European truffle which has not yet been successfully cultivated. Because of this, it is essential to safeguard natural truffières and to identify cultural practices to maximize their productivity. Soil tillage is successfully and extensively used in black truffle cultivation to enhance productivity, but its effects are not known on the development of T. magnatum. A recently developed real-time PCR assay was applied to evaluate the effects of tillage (10-15 cm depth) on T. magnatum mycelium in two different natural truffle grounds located in Tuscany and Emilia-Romagna. Tillage effects on bulk density, ectomycorrhizal fungal communities, and ascoma production were also assessed. Tilling significantly increased the quantity of T. magnatum mycelium which seemed to be related to an increase in soil porosity by up to 34%, and the diversity of ectomycorrhizal fungal communities. On the contrary, no significant effects were found on ascoma production. The results highlight that real-time PCR is the most reliable method for evaluating the effects of cultural practices on the development of T. magnatum in soil avoiding long-term studies on fruiting body production.

Uncommon ectomycorrhizal networks: richness and distribution of Alnus‐associating ectomycorrhizal fungal communities

Uncommon ectomycorrhizal networks: richness and distribution of <i>Alnus</i>‐associating ectomycorrhizal fungal communities

New wrinkles in an old paradigm: neighborhood effects can modify the structure and specificity ofAlnus-associated ectomycorrhizal fungal communities

Host identity has been recognized as a key determinant of the structure of ectomycorrhizal (ECM) fungal communities, but the importance of neighboring ECM hosts is less well understood. To investigate the relative importance of host and neighborhood effects, we examined the ECM fungal communities associated with Alnus rhombifolia, a host of specific ECM fungi, and Betula occidentalis, a host of generalist ECM fungi. We hypothesized that the host-specific Alnus-associated ECM fungal community would not be susceptible to the influence of plant neighborhood, while the generalist Betula-associated community would. ECM fungal communities on both hosts were characterized using ITS sequences derived from conspecific and heterospecific host settings at a field site in western Idaho, USA, and from a growth chamber bioassay. In the field study, the Betula neighborhood added minor constituents to the Alnus ECM fungal community, while in the bioassay, late planting of Betula generated strong priority effects that allowed the established Alnus neighborhood to control the structure of the Betula community. Our results indicate that while host identity acts as a primary filter on the composition and diversity of ECM fungal communities, proximity to a closely related host can mediate significant changes in community structure.

Species and functional diversity of ectomycorrhizal fungal communities on Scots pine (Pinus sylvestris L.) trees on three different sites

In the present study, we describe the aboveground (epigeous sporocarps) and belowground (ectomycorrhizal root tips and their exploration types) composition of ectomycorrhizal (ECM) fungal species on three 20-year-old Scots pine sites. The aim of this study was to relate the composition of ECM species to history of the site, stand density and soil chemistry (pH, toxic metal content, etc.) and to show how variable site condition contribute to above- and belowground ECM community changes. ECM fungi were identified by combination of morphotyping and direct sequencing of the PCR-amplified internal-transcribed spacer of n-rDNA. By identifying sporocarps and mycorrhizas, we detected a total of 54 taxa of ECM fungi: 28, 30, and 23 species at the Kórnik (control), Luboń (near the chemical plant) and Głogów (near the Copper Smelter, heavy metal influenced) sites, respectively. The sporocarp survey weakly reflected the analysis of ECM tips in terms of species composition, and largely supplemented the belowground view. Wilcoxina rehmii was the belowground-dominating species at all three sites and was found at the highest abundance at the site established after the clear cut of poplars and with the highest tree density (Kórnik). At the Luboń site, subdominant mycorrhizas were formed by Phialophora finlandia. On the site near the Copper Smelter in Głogów, a significant shift in species composition was observed compared with the two other sites and a very large proportion of medium-fringe exploration type belonging to Atheliaceae was found. Despite the partial overlap in the nonmetric multi-dimensional scaling ordination, analysis of similarity revealed significant differences between tested sites. Because of the number of covarying site properties which may influence ECM communities, it is difficult, if not unfeasible, to separate the precise reasons of the distribution of ECM fungi. Continued research on the biodiversity of ECM fungi in field sites along an environmental gradient would greatly improve our understanding of the effects of ecological conditions on the functional diversity of mycorrhizal fungi.

Towards a global view of ectomycorrhizal ecology

Towards a global view of ectomycorrhizal ecology

Chronic nitrogen enrichment affects the structure and function of the soil microbial community in temperate hardwood and pine forests

We examined how chronic nitrogen (N) enrichment of pine and hardwood forest stands has affected the relative abundance, functional capacity, and activity of soil bacteria and fungi. During Fall 2002 we collected one soil core (5.6 cm diameter; organic horizon plus 10 cm of mineral soil) from each of four 5 m×5 m subplots within the control, low N (5 g N m −2 per year), and high N (15 g N m −2 per year) plots in both the hardwood and pine stands at the Chronic Nitrogen Amendment Study at Harvard Forest. The samples were analyzed for total and active bacterial and fungal biomass, microbial catabolic response profiles, the activities of cellulolytic and ligninolytic enzymes, and total, labile and microbially derived organic carbon (C). Live, fine roots were also collected from the control and low N pine plots and analyzed for ectomycorrhizal fungal community composition and diversity. Active fungal biomass was 27–61% and 42–69% lower in the fertilized compared to control plots in the hardwood and pine stands, respectively. Active bacterial biomass was not greatly affected by N additions, resulting in significantly lower fungal:bacterial biomass ratios in the N-treated plots. This shift in microbial community composition was accompanied by a significant reduction in the activity of phenol oxidase, a lignin-degrading enzyme produced by white-rot fungi. In the pine stand, ectomycorrhizal fungal community diversity was lower in the low N-treated plot than in the control plot. Differences in ectomycorrhizal community structure were also detected between control and fertilized pine plots, including a reduction in those species with the highest relative frequencies in the control community. Finally, N enrichment altered the pattern of microbial substrate use, with the relative response to the addition of carboxylic acids and carbohydrates being significantly lower in the N-treated plots, even after the data were normalized to account for differences in microbial biomass. These patterns are consistent with lower decomposition rates and altered N cycling observed previously at this site.

Chronic nitrogen enrichment affects the structure and function of the soil microbial community in temperate hardwood and pine forests

We examined how chronic nitrogen (N) enrichment of pine and hardwood forest stands has affected the relative abundance, functional capacity, and activity of soil bacteria and fungi. During Fall 2002 we collected one soil core (5.6 cm diameter; organic horizon plus 10 cm of mineral soil) from each of four 5m×5 m subplots within the control, low N (5 g N m−2 per year), and high N (15 g N m−2 per year) plots in both the hardwood and pine stands at the Chronic Nitrogen Amendment Study at Harvard Forest. The samples were analyzed for total and active bacterial and fungal biomass, microbial catabolic response profiles, the activities of cellulolytic and ligninolytic enzymes, and total, labile and microbially derived organic carbon (C). Live, fine roots were also collected from the control and low N pine plots and analyzed for ectomycorrhizal fungal community composition and diversity. Active fungal biomass was 27–61% and 42–69% lower in the fertilized compared to control plots in the hardwood and pine stands, respectively. Active bacterial biomass was not greatly affected by N additions, resulting in significantly lower fungal:bacterial biomass ratios in the N-treated plots. This shift in microbial community composition was accompanied by a significant reduction in the activity of phenol oxidase, a lignin-degrading enzyme produced by white-rot fungi. In the pine stand, ectomycorrhizal fungal community diversity was lower in the low N-treated plot than in the control plot. Differences in ectomycorrhizal community structure were also detected between control and fertilized pine plots, including a reduction in those species with the highest relative frequencies in the control community. Finally, N enrichment altered the pattern of microbial substrate use, with the relative response to the addition of carboxylic acids and carbohydrates being significantly lower in the N-treated plots, even after the data were normalized to account for differences in microbial biomass. These patterns are consistent with lower decomposition rates and altered N cycling observed previously at this site.

Diversity of an ectomycorrhizal fungal community studied by a root tip and total soil DNA approach.

Molecular methods based on soil DNA extracts are increasingly being used to study the fungal diversity of ectomycorrhizal (EM) fungal communities in soil. Contrary to EM root tip identification, the use of molecular methods enables identification of extramatrical mycelia in soil. To compare fungal diversity as determined by root tip identification and mycelial identification, six soil samples were analysed. Root tips were extracted from the six samples and after amplification, the basidiomycete diversity on the root tips was analysed by denaturing gradient gel electrophoresis (DGGE). The soil from the six samples was sieved, total soil DNA was extracted and after amplification, the basidiomycete diversity in the soil fractions was analysed by DGGE. Fourteen different bands were excised from the DGGE gel and sequenced; fungal taxon names could be assigned to eight bands. Out of a total of 14 fungal taxa detected in soil, 11 fungal taxa were found on root tips, of which seven were EM fungal taxa. To examine whether the sieving treatment would affect EM species diversity, two different sieve mesh sizes were used and in addition, the organic soil fraction was analysed separately. DGGE analysis showed no differences in banding pattern for the different soil fractions. The organic fraction gave the highest DGGE band intensities. This work demonstrates that there is a high correspondence between basidiomycete diversity detected by molecular analysis of root tips and soil samples, irrespective of the soil fraction being analysed.