Fungal Operational Taxonomic Units Richness Research Articles

Effects of Cadmium Stress on Bacterial and Fungal Communities in the Whitefly Bemisia tabaci.

Heavy metal contamination is among the most prominent environmental problems in China, posing serious threats to both ecosystem and human health. Among the diverse heavy metal contaminants, cadmium is the most serious. The whitefly Bemisia tabaci is a cosmopolitan pest capable of causing severe damage to a broad range of agricultural crops, especially vegetables. At present, little is known about the effects of cadmium stress on B. tabaci, including on its bacterial and fungal communities. In the current study, we investigated the effects of cadmium on bacterial and fungal communities in whiteflies. Meta-barcode sequencing of the 16S rRNA gene revealed that the whitefly bacterial community contained 264 operational taxonomic units (OTUs) belonging to 201 known genera and 245 known species. The top five most frequent bacterial genera were Rickettsia, Rhodococcus, Candidatus Portiera, Candidatus Hamiltonella, and Achromobacter. Meta-barcode sequencing of the fungal ITS locus revealed that the whitefly fungal community contained 357 OTUs belonging to 187 known genera and 248 known species. The top five most frequent fungal genera were Wallemia, unclassified_f_Dipodascaceae, Apiotrichum, Penicillium, and unclassified_o_Saccharomycetales. Cadmium exposure reduced the fungal OTU richness but increased the bacterial Shannon and Simpson diversity indices in whiteflies. In addition, upon exposure to cadmium, the microbial community composition in whiteflies changed significantly, with increased prevalence of the bacterial genera Rhodococcus and Exiguobacterium and fungal genus Wallemia. Our results indicate that the whitefly microbiota likely contributed to their adaptation and resistance to cadmium and suggested that whiteflies may contain microbes that could help remediate cadmium contamination in natural environments and agricultural fields.

Does helimulching after severe wildfire affect soil fungal diversity and community composition in a Mediterranean ecosystem?

Straw helimulching was applied to an area with a high soil erosion risk one month after the Navalacruz megafire (Iberian Central System, Ávila, Spain) to mitigate soil erosion and to maintain soil quality. To determine whether the soil fungal community, which is key to soil and vegetation recovery after fire, is altered by straw mulching, we examined the effect of helimulching one year after its application. Three hillside zones were chosen with two treatments in each zone (mulched and non-mulched plots), with three replicates of each treatment. Chemical and genomic DNA analyses of soil samples from mulched and non-mulched plots were performed to assess the soil characteristics and the soil fungal community composition and abundance. The total fungal operational taxonomic unit richness and abundance did not differ between treatments. However, there was an increase in the richness of litter saprotrophs, plant pathogens and wood saprotrophs associated with the application of straw mulch. The total fungal composition of mulched and non-mulched plots differed significantly. Fungal composition at the phylum level correlated with the soil potassium content and marginally with the pH and phosphorus content. The application of mulch promoted the dominance of saprotrophic functional groups. Fungal composition according to guilds was also significantly different between treatments. As conclusion, the application of mulch could mean a faster recovery of saprotrophic functional groups that will be responsible for decomposing the available dead fine fuel.

Fungal diversity and community composition responses to the reintroduction of fire in a non-managed Mediterranean shrubland ecosystem

BackgroundMore than a decade of fire suppression has changed the structure of fire-adapted shrubland ecosystems in Spain's National Parks, which are now at extreme risk of uncontrolled wildfires. Prescribed burning can mitigate the risk of wildfires by reducing the fuel load but prescribed burning may also alter the soil properties and reduce microbial and fungal activity, causing changes in the availability of nutrients deep in the soil layer. Although fungal communities are a vital part of post-fire restoration, some fire effects remain unclear. To examine the short-term effects of prescribed burning on soil fungal communities in Doñana Biological Reserve (SW Spain), we collected soil samples pre-burn and 1 day, 6 and 12 months post-burn from burned plots to perform physicochemical and metabarcode DNA analyses. ResultsPrescribed burning had no significant effect on the total fungal operational taxonomic unit richness and abundance. However, changes in soil pH, nitrogen and potassium content post-burn affected fungal community composition. Small non-significant changes in pH and phosphorous affected the composition of ectomycorrhizal fungi. ConclusionsThe ectomycorrhizal fungal community appears to be resilient to the effects of low-to moderate-intensity fires and saprotrophic taxa may benefit from this kind of fire. This finding revealed that prescribed burning is a potentially valuable management tool for reducing fire hazards in shrublands that has little effect on the total richness and abundance of fungal communities.

Honeybees affect floral microbiome composition in a central food source for wild pollinators in boreal ecosystems

Basic knowledge on dispersal of microbes in pollinator networks is essential for plant, insect, and microbial ecology. Thorough understanding of the ecological consequences of honeybee farming on these complex plant–pollinator–microbe interactions is a prerequisite for sustainable honeybee keeping. Most research on plant–pollinator–microbe interactions have focused on temperate agricultural systems. Therefore, information on a wild plant that is a seasonal bottleneck for pollinators in cold climate such as Salix phylicifolia is of specific importance. We investigated how floral visitation by insects influences the community structure of bacteria and fungi in Salix phylicifolia inflorescences under natural conditions. Insect visitors were experimentally excluded with net bags. We analyzed the microbiome and measured pollen removal in open and bagged inflorescences in sites where honeybees were foraging and in sites without honeybees. Site and plant individual explained most of the variation in floral microbial communities. Insect visitation and honeybees had a smaller but significant effect on the community composition of microbes. Honeybees had a specific effect on the inflorescence microbiome and, e.g., increased the relative abundance of operational taxonomic units (OTUs) from the bacterial order Lactobacillales. Site had a significant effect on the amount of pollen removed from inflorescences but this was not due to honeybees. Insect visitors increased bacterial and especially fungal OTU richness in the inflorescences. Pollinator visits explained 38% variation in fungal richness, but only 10% in bacterial richness. Our work shows that honeybee farming affects the floral microbiome in a wild plant in rural boreal ecosystems.

Community structure and environmental determinants of the bacterial and fungal gut microflora in Hainan gibbons (Nomascus hainanus)

High-throughput sequencing technology was used to establish the OTU (Operational Taxonomic Units) composition and diversity of bacteria and fungi in the gut of three family groups of Hainan gibbons ( Nomascus hainanus ) in the Bawangling National Nature Reserve on Hainan Island, southern China. Firmicutes (47.23%) and Bacteroidetes (36.54%) predominated at the phylum level, while the predominant genera were Prevotella-7 (15.30%), Lachnospiraceae_NK3A20_group (12.49%), and uncultured_bacterium_f_Erysipelotrichaceae (11.79%). At the phylum level, the dominant fungi were Ascomycota (66.41%), as well as Hanseniaspora (23.33%), Schwanniomyces (13.44%), and Pichia (5.43%) at the genus level. We found significant differences in the bacterial OTU diversity (Shannon index) between family groups living in Tropical Lowland or Tropical Montane Rain Forest, compared to those inhabiting Tropical Montane Evergreen Forest at higher altitudes. Bacterial OTU community composition also differed between family groups, unraveling significant differences among the 30 most dominant bacterial core taxa. Furthermore, we unraveled a significant difference of OTU richness in the fungal microbiome (Chao 1) between family groups living at lower altitudes, i.e., Tropical Lowland or Tropical Montane Rain Forest and those inhabiting the Tropical Montane Evergreen Forest. Our analysis further indicated significant differences in the fungal OTU community composition between the three family groups, especially regarding the three most dominant fungal core taxa. Subsequently, two habitat factors, and nine environmental and anthropogenic variables were used to explore possible causes of disparity in the microbial flora of gibbon groups. A factor reduction procedure resulted into three principal components which were correlated to bacterial and fungal OTU richness and diversity using Spearman's rank-order correlations. Bacterial and fungal OTU diversity was high in areas of high altitude, steep slopes, high tree density, but low tree height, while high fungal OTU richness corresponded to high altitude habitats, i.e., in the Tropical Montane Evergreen Forest. Distance to human settlements and to the next water body showed no significant relation with bacterial and fungal richness and diversity.

Fungal Diversity and Community Assembly of Ectomycorrhizal Fungi Associated With Five Pine Species in Inner Mongolia, China.

Ectomycorrhizal (EM) fungi play vital roles in ensuring host plants’ health, plant diversity, and the functionality of the ecosystem. However, EM fungal diversity, community composition, and underlying assembly processes in Inner Mongolia, China, where forests are typically semiarid and cold-temperate zones, attract less attention. In this study, we investigated EM fungal communities from 63 root samples of five common pine plants in Inner Mongolia across 1,900 km using Illumina Miseq sequencing of the fungal internal transcribed spacer 2 region. We evaluated the impact of host plant phylogeny, soil, climatic, and spatial variables on EM fungal diversity and community turnover. Deterministic vs. stochastic processes for EM fungal community assembly were quantified using β-nearest taxon index scores. In total, we identified 288 EM fungal operational taxonomic units (OTUs) belonging to 31 lineages, of which the most abundant lineages were Tomentella–Thelephora, Wilcoxina, Tricholoma, and Suillus–Rhizopogon. Variations in EM fungal OTU richness and community composition were significantly predicted by host phylogeny, soil (total nitrogen, phosphorus, nitrogen–phosphorus ratio, and magnesium), climate, and spatial distance, with the host plant being the most important factor. β-nearest taxon index demonstrated that both deterministic and stochastic processes jointly determined the community assembly of EM fungi, with the predominance of stochastic processes. At the Saihanwula site selected for preference analysis, all plant species (100%) presented significant preferences for EM fungi, 54% of abundant EM fungal OTUs showed significant preferences for host plants, and 26% of pairs of plant species and abundant fungal OTUs exhibited remarkably strong preferences. Overall, we inferred that the high diversity and distinctive community composition of EM fungi associated with natural pine species in Inner Mongolia and the stochastic processes prevailed in determining the community assembly of EM fungi. Our study shed light on the diversity and community assembly of EM fungi associated with common pine species in semiarid and cold temperate forests in Inner Mongolia, China, for the first time and provided a better understanding of the ecological processes underlying the community assembly of mutualistic fungi.

Tree species composition and nutrient availability affect soil microbial diversity and composition across forest types in subtropical China

Soil microorganisms represent a significant component of terrestrial biodiversity and play a critical role in myriad ecological processes. The conversion of native forests to tree plantations is a major contributor to biodiversity loss on a global scale; however, our understanding of the influences of forest type conversion on soil microbial diversity and community composition remains unclear. Here we sampled twelve spatially interspersed stands of native mixed broadleaf forests, broadleaf-dominated (50–70% broadleaf trees), bamboo-dominated (20–40% broadleaf trees), and pure bamboo forests in subtropical China, to examine the effects of forest type conversion on soil bacterial and fungal diversity and composition. We found that the tree species richness, stand basal area, and soil carbon to nitrogen ratio decreased, while the total soil phosphorus increased from the native broadleaf forests to pure bamboo forests. Bacterial and fungal operational taxonomic units (OTUs) across the three soil depths increased significantly from 760 and 243 in native broadleaf to 795 and 336 in pure bamboo forests, respectively. However, neither bacterial nor fungal richness differed significantly among forest types at the phylum level. Across forest types, both bacterial and fungal OTU richness increased with the bamboo proportion and decreased with the soil carbon and nitrogen ratio. The fungal OTU richness also increased with the soil phosphorus content; however, neither bacterial nor fungal richness was affected by the tree species richness or stand basal area. Both bacterial and fungal community compositions changed with forest type and soil depth, with their compositional overlap from native broadleaf forests decreasing consistently with the bamboo proportion and soil phosphorus. Overall, our results provide insights into the importance of overstory tree composition and the availability of soil nutrients in affecting soil microbial diversity and composition, while providing management guidance for the inclusion of soil microbial diversity in forest conservation and management.

Plant identity strongly structures the root-associated fungal community in a diverse subtropical forest

Revealing the relationship between plants and root-associated fungi is very important in understanding diversity maintenance and community assembly in ecosystems. However, the community assembly of root-associated fungi of focal plant species along a subtropical plant species diversity gradient is less documented. Here, we examined root-associated fungal communities associated with five ectomycorrhizal (EM) plant species (Betula luminifera, Castanea henryi, Castanopsis fargesii, C. sclerophylla, and Quercus serrate) in a Chinese subtropical woody plant species diversity (1, 2, 4, 8, 16 and 24 species) experiment, using paired-end Illumina MiSeq sequencing of the ITS2 region. In total, we detected 1933 root-associated fungal operational taxonomic units (OTUs) at a 97% sequence similarity level. Plant identity had a significant effect on total and saprotrophic fungal OTU richness, but plant species diversity level had a significant effect on saprotrophic and pathogenic fungal OTU richness. The community composition of total, saprotrophic and EM fungi was structured by plant identity and plant species diversity level. However, the community composition of pathogenic fungi was only shaped by plant identity. This study highlights that plant identity has a stronger effect on the root-associated fungal community than plant species diversity level in a diverse subtropical forest ecosystem.

Community Assembly of Endophytic Fungi in Ectomycorrhizae of Betulaceae Plants at a Regional Scale.

The interaction between aboveground and belowground biotic communities drives community assembly of plants and soil microbiota. As an important component of belowground microorganisms, root-associated fungi play pivotal roles in biodiversity maintenance and community assembly of host plants. The Betulaceae plants form ectomycorrhizae with soil fungi and widely distribute in various ecosystems. However, the community assembly of endophytic fungi in ectomycorrhizae is less investigated at a large spatial scale. Here, we examined the endophytic fungal communities in ectomycorrhizae of 22 species in four genera belonging to Betulaceae in Chinese forest ecosystems, using Illumina Miseq sequencing of internal transcribed spacer 2 amplicons. The relative contribution of host phylogeny, climate and soil (environmental filtering) and geographic distance (dispersal limitation) on endophytic fungal community was disentangled. In total, 2,106 endophytic fungal operational taxonomic units (OTUs) were obtained at a 97% sequence similarity level, dominated by Leotiomycetes, Agaricomycetes, Eurotiomycetes, and Sordariomycetes. The endophytic fungal OTU richness was significantly related with host phylogeny, geographic distance, soil and climate. The endophytic fungal community composition was significantly affected by host phylogeny (19.5% of variation explained in fungal community), geographic distance (11.2%), soil (6.1%), and climate (1.4%). This finding suggests that environmental filtering by plant and abiotic variables coupled with dispersal limitation linked to geographic distance determines endophytic fungal community assembly in ectomycorrhizae of Betulaceae plants, with host phylogeny being a stronger determinant than other predictor variables at the regional scale.

Arbuscular mycorrhizal fungal community was affected by tillage practices rather than residue management in black soil of northeast China

Arbuscular mycorrhizal (AM) fungi are one of the most important soil microbes in an agrarian ecosystem, and consequently affected by various agricultural practices. To elucidate the effects of tillage practices and residue management on AM fungi, a field trial was conducted on the Songnen Plain, Northeast China. We examined the effects of different tillage practices including no-tillage (NT), rotary tillage (RT), subsoil tillage (ST) and deep tillage (DT) on the AM fungal biomass, diversity and community under residue removal and residue retention. AM root colonization and extraradical hyphal (ERH) density were significantly higher in DT treatment compared with NT treatment, whereas an opposite trend was observed for AM fungal spore density. Structural equation modeling indicated that AM fungal spore density was directly affected by tillage practices. Albeit, the effect of tillage practices on ERH density was mainly mediated through root length of maize. By Miseq sequencing of 18S rDNA, 66 AM fungal operational taxonomic units (OTUs) were identified and Glomeraceae was the most abundant group in this study. AM fungal OTU richness was highest in treatment NT, and significantly higher than that in treatment DT. Non-metric multidimensional scaling analysis indicated that treatment DT and ST induced a distinct AM fungal community composition compared with treatment NT. On the other hand, residue did not significantly influence AM fungal biomass, OTU richness and community composition. Overall, our findings indicated that tillage practice is a stronger determinant than residue management in AM fungal development and community composition in black soil on the Songnen Plain.

Arbuscular mycorrhizal fungal community differentiation along a post-coal mining reclamation chronosequence in South Africa: A potential indicator of ecosystem recovery

Arbuscular mycorrhizal (AM) fungi contribute to the restoration of soil ecological functions and processes during ecosystem development. Here, diversity and differentiation of AM fungi in rhizosphere soils and roots of the dominant vegetation along a post-coal mining reclamation soil chronosequence of 3, 11, 15, 19 and 24 years after reclamation were investigated. High-throughput sequence analysis of partial Glomeromycotan 18S rRNA in soils and roots revealed a high number of core operational taxonomic units (OTUs) across chronosequence. Arbuscular mycorrhizal fungal (AMF) OTU richness, Shannon-Weiner index and species dominance were not significantly different across soil and root but were significantly (P < 0.05) correlated with ammonium, nitrate, silt fraction, litter, pH, foliar and/or basal covers. AMF community structure was significantly different (P < 0.05) across unmined and reclamation chronosequence soils, with differentiation between younger reclaimed areas (3 and 11 years) and older reclamation ages (19 and 24 years) in multivariate space. In contrast, structural differentiation in the AMF community colonising the single plant-host across the chronosequence was not significant (PERMANOVA, P > 0.05), although community composition and structure were heterogeneous within 3–11 years but similar within 15–24 years. Seven Glomeromycotan genera were detected in soil and roots, including the relatively dominant Glomus genus, and the differentially abundant Acaulospora, Diversispora, Paraglomus and Scutellospora in either earlier or later years since post-mining reclamation. Canonical correspondence analysis revealed that nitrates (NO3-N), clay content and bulk density significantly influenced (P < 0.05) the AMF community structure in soil, whereas, the AMF community in root was not significantly influenced (P > 0.05) by environmental variables. Overall, the study suggests that AMF community differentiation reflect ecosystem development over chronological space-time. Thus, AMF species differentiation may be included as part of a minimum dataset for monitoring ecosystem restoration following post-mining reclamation.

First Insights into the Microbiome of a Mangrove Tree Reveal Significant Differences in Taxonomic and Functional Composition among Plant and Soil Compartments.

Mangrove forest trees play important ecological functions at the interface between terrestrial and marine ecosystems. However, despite playing crucial roles in plant health and productivity, there is little information on microbiomes of the tree species in mangrove ecosystems. Thus, in this study we aimed to characterize the microbiome in soil (rhizosphere) and plant (root, stem, and leaf endosphere) compartments of the widely distributed mangrove tree Rhizophora stylosa. Surprisingly, bacterial operational taxonomic units (OTUs) were only confidently detected in rhizosphere soil, while fungal OTUs were detected in all soil and plant compartments. The major detected bacterial phyla were affiliated to Proteobacteria, Actinobacteria, Planctomycetes, and Chloroflexi. Several nitrogen-fixing bacterial OTUs were detected, and the presence of nitrogen-fixing bacteria was confirmed by nifH gene based-PCR in all rhizosphere soil samples, indicating their involvement in N acquisition in the focal mangrove ecosystem. We detected taxonomically (54 families, 83 genera) and functionally diverse fungi in the R. stylosa mycobiome. Ascomycota (mainly Dothideomycetes, Eurotiomycetes, Sordariomycetes) were most diverse in the mycobiome, accounting for 86% of total detected fungal OTUs. We found significant differences in fungal taxonomic and functional community composition among the soil and plant compartments. We also detected significant differences in fungal OTU richness (p < 0.002) and community composition (p < 0.001) among plant compartments. The results provide the first information on the microbiome of rhizosphere soil to leaf compartments of mangrove trees and associated indications of ecological functions in mangrove ecosystems.

Shared mycorrhizae but distinct communities of other root-associated microbes on co-occurring native and invasive maples.

BackgroundBiological invasions are major drivers of environmental change that can significantly alter ecosystem function and diversity. In plants, soil microbes play an important role in plant establishment and growth; however, relatively little is known about the role they might play in biological invasions. A first step to assess whether root microbes may be playing a role in the invasion process is to find out if invasive plants host different microbes than neighbouring native plant species.MethodsIn this study we investigated differences in root associated microbes of native sugar maple (Acer saccharum Marsh.) and exotic Norway maple (A. platanoides L.) collected from a forested reserve in eastern Canada. We used microscopy to examine root fungi and high-throughput sequencing to characterize the bacterial, fungal and arbuscular mycorrhizal communities of both maple species over one growing season.ResultsWe found differences in root associated bacterial and fungal communities between host species. Norway maple had a higher bacterial and fungal OTU (operational taxonomic units) richness compared to sugar maple, and the indicator species analysis revealed that nine fungal OTUs and three bacterial OTUs had a significant preference for sugar maple. The dominant bacterial phyla found on the roots of both maple species were Actinobacteria and Proteobacteria. The most common fungal orders associated with the Norway maple roots (in descending order) were Helotiales, Agaricales, Pleosporales, Hypocreales, Trechisporales while the Agaricales, Pleosporales, Helotiales, Capnodiales and Hypocreales were the dominant orders present in the sugar maple roots. Dark septate fungi colonization levels were higher in the sugar maple, but no differences in arbuscular mycorrhizal fungal communities and colonization rates were detected between maple species.DiscussionOur findings show that two congeneric plant species grown in close proximity can harbor distinct root microbial communities. These findings provide further support for the importance of plant species in structuring root associated microbe communities. The high colonization levels observed in Norway maple demonstrates its compatibility with arbuscular mycorrhizal fungi in the introduced range. Plant-associated microbial communities can affect host fitness and function in many ways; therefore, the observed differences suggest a possibility that biotic interactions can influence the dynamics between native and invasive species.

Intraradical and extraradical communities of AM fungi associated with alfalfa respond differently to long-term phosphorus fertilization

To investigate the responses of alfalfa root-/ soil-associated arbuscular mycorrhizal (AM) fungal communities to phosphorus (P) addition, we examined the intraradical and extraradical mycorrhizal communities in an alfalfa (Medicago sativa) field being fertilized with four levels of P for 9 years. We found that AM fungal colonization declined significantly at the highest P level and was negatively related to soil available phosphorus, suggesting a decreased reliance on AM fungi at this high P level. A total of 22 operational taxonomic units (OTUs) from three families were detected in roots and 25 in soil. Both AM fungal OTU richness and diversity in soil were higher than that in roots. The AM fungal diversity in roots declined significantly when P was the highest. The indicator species in roots increased in relative abundance in the P1 treatment (75 kg P2O5 ha−1 a−1). Although P addition had no significant effect on OTU richness or AM fungal community composition in soil, we found that pH and soil organic matter structured roots and soil mycorrhizal communities, respectively. In conclusion, P addition affected root and soil AM fungal communities differently. Further research is needed to determine how individual AM fungal species may respond to P fertilization, and how this may impact plant productivity.

Effect of drought and season on arbuscular mycorrhizal fungi in a subtropical secondary forest

Arbuscular mycorrhizal (AM) fungi in both soil and roots were examined in May (summer) and December (winter) under a 4-y drought experiment in a Chinese subtropical secondary forest. Drought significantly decreased AM fungal extra-radical hyphal density, spore density, and root colonization rate in both seasons. These AM parameters were significantly higher in summer than in winter in the control treatment, but only AM fungal extra-radical hyphal density exhibited the same seasonal trend in the drought treatment. In total, 45 AM fungal operational taxonomic units (OTUs) were obtained at a 97% sequence similarity level using Illumina sequencing of 18S rDNA. Drought and season had no significant effects on AM fungal OTU richness in soil and roots. AM fungal community composition in soil and roots was significantly affected by season but not by drought. This finding enhances our understanding of the response of AM fungi to global climate change in subtropical forest ecosystems. • AM fungal abundance was decreased by drought in both seasons. • AM fungal richness was not affected by drought or season. • AM fungal community composition was influenced by season but not by drought.

Host plant phylogeny and geographic distance strongly structure Betulaceae-associated ectomycorrhizal fungal communities in Chinese secondary forest ecosystems.

Environmental filtering and dispersal limitation are two of the primary drivers of community assembly in ecosystems, but their effects on ectomycorrhizal (EM) fungal communities associated with wide ranges of Betulaceae taxa at a large scale are poorly documented. In this study, we examined EM fungal communities associated with 23 species from four genera (Alnus, Betula, Carpinus and Corylus) of Betulaceae in Chinese secondary forest ecosystems, using Illumina MiSeq sequencing of the ITS2 region. Effects of host plant phylogeny, soil, climate and geographic distance on EM fungal community were explored. In total, we distinguished 1738 EM fungal operational taxonomic units (OTUs) at a 97% sequence similarity level. The EM fungal communities of Alnus had significantly lower OTU richness than those associated with the other three plant genera. The EM fungal OTU richness was significantly affected by geographic distance, host plant phylogeny, soil and climate. The EM fungal community composition was significantly influenced by host plant phylogeny (12.1% of variation explained in EM fungal community), geographic distance (7.7%), soil (4.6%) and climate (1.1%). This finding highlights that environmental filtering linked to host plant phylogeny and dispersal limitation strongly influence EM fungal communities associated with Betulaceae plants in Chinese secondary forest ecosystems.

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

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

Compost Addition Enhanced Hyphal Growth and Sporulation of Arbuscular Mycorrhizal Fungi without Affecting Their Community Composition in the Soil.

Arbuscular mycorrhizal (AM) fungi form symbiotic associations with most crop plant species in agricultural ecosystems, and are conspicuously influenced by various agricultural practices. To understand the impact of compost addition on AM fungi, we examined effect of four compost rates (0, 11.25, 22.5, and 45 Mg/ha) on the abundance and community composition of AM fungi in seedling, flowering, and mature stage of soybean in a 1-year compost addition experiment system in Northeast China. Soybean [Glycine max (L.) Merrill] was used as test plant. Moderate (22.5 Mg/ha) and high (45 Mg/ha) levels of compost addition significantly increased AM root colonization and extraradical hyphal (ERH) density compared with control, whereas low (11.5 Mg/ha) level of compost addition did not cause significant increase in AM root colonization and ERH density. AM fungal spore density was significantly enhanced by all the compost rates compared with control. The temporal variations analysis revealed that, AM root colonization in seedling stage was significantly lower than in flowering and mature stage. Although AM fungal operational taxonomic unit richness and community composition was unaffected by compost addition, some abundant AM fungal species showed significantly different response to compost addition. In mature stage, Rhizophagus fasciculatum showed increasing trend along with compost addition gradient, whereas the opposite was observed with Paraglomus sp. In addition, AM fungal community composition exhibited significant temporal variation during growing season. Further analysis indicated that the temporal variation in AM fungal community only occurred in control treatment, but not in low, moderate, and high level of compost addition treatments. Our findings highlighted the significant effects of compost addition on AM growth and sporulation, and emphasized that growth stage is a stronger determinant than 1-year compost addition in shaping AM fungal community in black soil of Northeast China.

Organic farming increases richness of fungal taxa in the wheat phyllosphere.

Organic farming is often advocated as an approach to mitigate biodiversity loss on agricultural land. The phyllosphere provides a habitat for diverse fungal communities that are important for plant health and productivity. However, it is still unknown how organic farming affects the diversity of phyllosphere fungi in major crops. We sampled wheat leaves from 22 organically and conventionally cultivated fields in Sweden, paired based on their geographical location and wheat cultivar. Fungal communities were described using amplicon sequencing and real-time PCR. Species richness was higher on wheat leaves from organically managed fields, with a mean of 54 operational taxonomic units (OTUs) compared with 40 OTUs for conventionally managed fields. The main components of the fungal community were similar throughout the 350-km-long sampling area, and seven OTUs were present in all fields: Zymoseptoria, Dioszegia fristingensis, Cladosporium, Dioszegia hungarica, Cryptococcus, Ascochyta and Dioszegia. Fungal abundance was highly variable between fields, 103 -105 internal transcribed spacer copies per ng wheat DNA, but did not differ between cropping systems. Further analyses showed that weed biomass was the strongest explanatory variable for fungal community composition and OTU richness. These findings help provide a more comprehensive understanding of the effect of organic farming on the diversity of organism groups in different habitats within the agroecosystem.

Arbuscular mycorrhizal fungal community composition affected by original elevation rather than translocation along an altitudinal gradient on the Qinghai-Tibet Plateau.

Elucidating arbuscular mycorrhizal (AM) fungal responses to elevation changes is critical to improve understanding of microbial function in ecosystems under global asymmetrical climate change scenarios. Here we examined AM fungal community in a two-year reciprocal translocation of vegetation-intact soil blocks along an altitudinal gradient (3,200 m to 3,800 m) in an alpine meadow on the Qinghai-Tibet Plateau. AM fungal spore density was significantly higher at lower elevation than at higher elevation regardless of translocation, except that this parameter was significantly increased by upward translocation from original 3,200 m to 3,400 m and 3,600 m. Seventy-three operational taxonomic units (OTUs) of AM fungi were recovered using 454-pyrosequencing of 18S rDNA sequences at a 97% sequence similarity. Original elevation, downward translocation and upward translocation did not significantly affect AM fungal OTU richness. However, with increasing altitude the OTU richness of Acaulosporaceae and Ambisporaceae increased, but the OTU richness of Gigasporaceae and Glomeraceae decreased generally. The AM fungal community composition was significantly structured by original elevation but not by downward translocation and upward translocation. Our findings highlight that compared with the short-term reciprocal translocation, original elevation is a stronger determinant in shaping AM fungal community in the Qinghai-Tibet alpine meadow.