Diversity Of Fungal Communities Research Articles

Climate and geochemistry at different altitudes influence soil fungal community aggregation patterns in alpine grasslands

Fungi represent key ecosystem factors that affect plant growth and development and improve soil structure and fertility. Due to changes in environmental conditions, fungi show strong spatial heterogeneity along altitudinal gradients. Current knowledge of the driving mechanisms and effects of soil fungal community construction at high altitudes is very limited on a regional scale. We collected soil samples from alpine grasslands at six altitudinal gradients (2813–5228 m) in the high-altitude area of the Qinghai-Tibet Plateau. The horizontal distance of the sampling zone spanned 1500 km. Distribution patterns, key influencing factors for soil fungal diversity, and dominant mechanisms of ecological processes in the alpine grasslands were analyzed. We found that the diversity of the soil fungal communities was significantly different at different altitudes; with increasing altitude, the number of fungal species increased. Mucoromycota was better adapted to alpine grassland ecosystems at altitudes of above 4000 m. Dispersal limitation was the main ecological control process among stochastic processes. With the increase of altitude, the dominant role of dispersal limitation gradually decreased, and the proportion of other random processes such as ecological drift gradually increased. In this study, soil geochemical factors (soil organic carbon, SOC; total phosphorus, TP) mainly influenced the composition of the fungal community in the low altitude region, while climatic factors (mean annual temperature, MAT) were the key factors and main driving forces for the composition of the soil fungal community in the alpine meadow in the high altitude region. This study supplements the information on the biogeographic distribution patterns and environmental drivers of fungal communities along altitudinal gradients at high altitudes on a regional scale. Our results highlight the effects of temperature change on fungal community composition in high altitude regions of alpine grasslands. Subsurface fungal communities should be considered when predicting the function of alpine grassland ecosystems under future climate change.

Plant invasion mediates the regulation of topsoil organic carbon sequestration by the fungal community in coastal wetlands

Spartina alterniflora, which is native to the Atlantic coast, has extensively invaded mangroves/marshes and hence seriously altered coastal soil organic carbon (SOC) sequestration along the Pacific coast. Fungi are directly engaged in the SOC cycle, but how the fungal community impacts coastal carbon sequestration in response to S. alterniflora invasion remains unclear. We explored the fungal community shifts in relation to SOC changes by comparing 6 pairs of independent sites (i.e., dominant native plants vs. S. alterniflora) along a 2,500 km coastal transect in southeastern China. Our results showed that the invasion reduced the fungal diversity and shifted the assemblage processes of the abundant subcommunity, not the rare subcommunity, from determinism (0.409) to stochasticity (0.556). The invasion decreased network topological properties (e.g., network size, centrality, natural connectivity, etc.), cohesion, robustness, and the relative abundance of keystone taxa but increased the vulnerability of the fungal community. Importantly, the Shannon index, total cohesion and keystone taxa of the fungal community were significantly positively correlated with SOC concentration, SOC storage and recalcitrant organic carbon (ROC) but not with labile organic carbon (LOC). The structural equation model further showed that the fungal community diversity, complexity and keystone taxa directly regulated SOC storage under S. alterniflora invasion. Overall, we provide new insights into fungal community shifts and cooccurrence patterns under S. alterniflora invasion, helping us better understand the impact of invasion on SOC cycling and its microbial mechanisms, which will benefit future restoration and optimal coastal management.

Potential of Medicago sativa and Perilla frutescens for overcoming the soil sickness caused by ginseng cultivation.

There are serious soil sickness in ginseng cultivation. Crop rotation is an effective agricultural management to improve soil sustainability and reduce soil sickness. To explore an appropriate ginseng rotation system, Medicago sativa (alfalfa) and Perilla frutescens (perilla) were planted on ginseng cultivation soil for 1 year to evaluate the improvement effect of both. Through chemical analysis and high-throughput sequencing technology, we found that after alfalfa and perilla cultivation for one-year, various nutrients and enzyme activities in ginseng cultivation soil were significantly improved. In addition, perilla significantly increased the diversity and richness of soil fungal communities. Cultivation of alfalfa and perilla significantly changed the composition of soil bacterial and fungal communities and significantly reduced the abundance of the potentially pathogenic fungi Ilyonectria. Further pot experiments also showed that the improved soil could significantly increase root activity of ginseng plant after two plants were planted. It should be noted that, unlike alfalfa, perilla decreased soil electrical conductivity, increased soil organic matter, soil urease, and may significantly improve the diversity and richness of soil fungal community. Moreover, in the pot experiment, the root fresh weight of ginseng cultured in perilla treated soil increased significantly. This study highlights that perilla may have better soil improvement effect than alfalfa and it has the potential to be used in the soil improvement of ginseng cultivation.

Belowground microbiota analysis indicates that Fusarium spp. exacerbate grapevine trunk disease

BackgroundGrapevine trunk diseases (GTDs) are disease complexes that are major threats to viticulture in most grapevine growing regions. The microbiomes colonizing plant belowground components form complex associations with plants, play important roles in promoting plant productivity and health in natural environments, and may be related to GTD development. To investigate associations between belowground fungal communities and GTD symptomatic or asymptomatic grapevines, fungal communities associated with three soil–plant compartments (bulk soils, rhizospheres, and roots) were characterized by ITS high-throughput amplicon sequencing across two years.ResultsThe fungal community diversity and composition differs according to the soil–plant compartment type (PERMANOVA, p < 0.001, 12.04% of variation explained) and sampling year (PERMANOVA, p < 0.001, 8.83%), whereas GTD symptomatology exhibited a weaker, but still significant association (PERMANOVA, p < 0.001, 1.29%). The effects of the latter were particularly prominent in root and rhizosphere community comparisons. Many GTD-associated pathogens were detected, but their relative abundances were not correlated (or were negatively correlated) to symptomatology. Fusarium spp., were enriched in symptomatic roots and rhizospheres compared to asymptomatic counterparts, suggesting that their abundances were positively correlated with symptomatic vines. Inoculation tests revealed that Fusarium isolates, similar to Dactylonectria macrodidyma, a pathogen associated with black foot disease, caused dark brown necrotic spots on stems in addition to root rot, which blackened lateral roots. Disease indices were higher with co-inoculation than single inoculation with a Fusarium isolate or D. macrodidyma, suggesting that Fusarium spp. can exacerbate disease severity when inoculated with other known GTD-associated pathogens.ConclusionsThe belowground fungal microbiota of grapevines varied from soil–plant compartments, the years and whether showed GTD symptoms. The GTDs symptoms were related to the enrichment of Fusarium spp. rather than the relative abundances of GTD pathogens. These results demonstrate the effects of fungal microbiota of roots and rhizospheres on GTDs, while providing new insights into opportunistic pathogenesis of GTDs and potential control practices.

Response of soil fungal community to chromium contamination in agricultural soils with different physicochemical properties

Chromium (Cr) contamination has been of great concern in agricultural soil health due to its persistence, toxicity and bioaccumulation. Fungi, as an essential regulator of soil remediation and biochemical processes, had an unclear response to Cr contamination. In this study, the composition, diversity and interaction mechanisms of fungal communities in agricultural soils from ten different provinces of China were investigated in order to elucidate the fungal community response to varying soil properties and Cr concentrations. The results showed that high concentrations of Cr led to substantial alterations in the fungal community composition. The complex soil properties had a far greater impact on the fungal community structure than the single factor of Cr concentration, with soil available phosphorus (AP) and pH being most influential. Function predictions based on FUNGuild indicated that high concentrations of Cr have a significant impact on certain functional groups of fungi, including mycorrhizal fungi and plant saprotroph. The fungal community tended to resist Cr stress by enhancing interactions and clustering among network modules, while generating new keystone taxa. This study allowed insights into the response of soil fungal community to Cr contamination in different agricultural soils from different provinces and provided a theoretical basis for soil Cr ecological risk assessment and the development of bioremediation techniques for Cr-contaminated soils.

Diversity and assembly of root-associated microbiomes of rubber trees.

Understanding the diversity and assembly of the microbiomes of plant roots is crucial to manipulate them for sustainable ecosystem functioning. However, there are few reports about microbial communities at a continuous fine-scale of roots for rubber trees. We investigate the structure, diversity, and assembly of bacterial and fungal communities for the soil (non-rhizosphere), rhizosphere, and rhizoplane as well as root endosphere of rubber trees using the amplicon sequencing of 16S ribosomal ribonucleic acid (rRNA) and Internally Transcribed Spacer (ITS) genes. We show that 18.69% of bacterial and 20.20% of fungal operational taxonomic units (OTUs) in the rhizoplane derived from the endosphere and 20.64% of bacterial and 20.60% of fungal OTUs from the soil. This suggests that the rhizoplane microbial community was a mixed community of soil and endosphere microbial communities and that microorganisms can disperse bidirectionally across different compartments of the plant root. On the other hand, in the absence of an enrichment or depletion of core bacterial and fungal OTUs in the rhizosphere, little differences in microbial composition as well as a more shared microbial network structure between the soil and the rhizosphere support the theory that the rhizosphere microbial community is a subset of the soil community. A large number of functional genes (such as nitrogen fixation and nitrite reduction) and more enriched core OTUs as well as a less stable but more complex network structure were observed in the rhizoplane of rubber tree roots. This demonstrated that the rhizoplane is the most active root compartment and a hotspot for plant-soil-environment interactions. In addition, bacterial and fungal communities in the rhizoplane were more stochastic compared to the rhizosphere and soil. Our study expands our understanding of root-associated microbial community structure and function, which may provide the scientific basis for sustainable agriculture through biological process management.

The core fungal microbiome of banana (Musa spp.).

Here, we report a metabarcoding (ITS2) study to define the common core fungal microbiome (mycobiome) of healthy Musa spp. (bananas and plantains). To identify a list of 21 core fungal taxa, we first characterised the effects of edaphic conditions and host genotype - two factors that are likely to differ between farms - on the diversity of fungal communities in bulk soil and seven plant compartments. This experiment facilitated shortlisting of core 'candidates', which were then elevated to full core status if also found to frequent a wide-range of field-grown Musa spp. and exhibit hub-like characteristics in network analyses. Subsequently, we conducted a meta-analysis of eleven publicly available datasets of Musa spp. associated fungi demonstrating that the core fungi identified in our study have close relatives in other countries. The diversity and composition of mycobiomes differed between plant compartments and soils, but not genotypes. The core mycobiome included Fusarium oxysporum and its relatives, which dominated all plant compartments, as well as members of the Sordariomycetes, Dothideomycetes, and Mortierellomycota. Our study provides a robust list of common core fungal taxa for Musa spp. Further studies may consider how changes in the frequencies and activities of these taxa influence host fitness and whether they can be managed to improve banana production.

Fungal-bacterial associations in urban allotment garden soils

The soil microbiome in urban agriculture has not received much attention to date despite its important role in soil functionality. In this work, we evaluated the composition and diversity of fungal and bacterial communities through DNA extraction and ITS/16S marker gene sequencing in 40 soil samples collected from 10 urban allotment garden areas in the city of Santiago de Compostela (northwestern Spain). Despite anthropogenic activities are expected to affect negatively the microbial diversity, the richness of both fungal and bacterial communities was comparable to that of soils from other urban land-use categories with lower anthropogenic influence, i.e., urban forests, urban grasslands, and urban agricultural fields. However, the deterministic effect of soil properties and geographical distances was almost negligible in the surveyed allotment gardens. Neutral community models confirmed that the fungal and bacterial communities followed a random distribution (pseudo-R2fungi|bacteria = 0.653 | 0.898) and that they were more random (tNSTfungi|bacteria = 0.54 | 0.74) compared to the other abovementioned land-use categories (tNSTfungi|bacteria = 0.46 | 0.67, p ≪ 0.001). Network analysis showed that in contrast to natural soils with lower anthropogenic influence, microbial associations formed very small modules; and frequently, microbial units remained unconnected. Taken together, our findings provide evidence that the soil microbial communities in the studied urban allotment gardens comprised a random assortment of microbes and their interactions, thereby supporting potential implications of anthropogenic activity for soil health and ultimately ecosystem functionality.

Linking fungal community structure with soil nitrogen dynamics following forest conversion in a subalpine forest in China

The conversion of natural forests to plantations affects soil carbon (C) and nitrogen (N) dynamics. However, the underlying microbial mechanisms of C and N dynamics caused by forest conversion, particularly the functional role of ectomycorrhizal (ECM) fungi, remain largely unknown. Here, we investigated the soil and root-associated fungal communities, soil and ECM root enzyme activities, and C and N mineralization rates in natural forests and plantations in the western Sichuan subalpine coniferous forest. Soil fungal and root ECM fungal communities were determined by high-throughput and Sanger sequencing, respectively. ECM root surface enzymes were used to assess fungal function, while soil enzymes, C and N mineralization, were used to evaluate soil function.Our results showed that clearing natural forests and converting them to plantations led to lower soil organic carbon (SOC), total nitrogen (TN), and pH, which drove changes in ECM and saprophytic (SAP) fungal communities. After forest conversion, the main difference in the fungal community was an increase in the ratio of ECM to SAP fungi. The most apparent change in the soil ECM fungal community is the shift of the dominant genera from Russula to Cortinarius and Piloderma. Subsequently, the function of the ECM fungal community was altered. The results indicated that the conversion of the natural forest to the plantation reduced ECM community β-glucosidase (βG), β-glucuronidase (βLU), N-acetyl-β-D-glucosaminidase (NAG), and acid phosphatase (AP) activities, and soil βG, NAG, and leucine aminopeptidase (LAP) activities. Among them, the activities of βG, βLU, and NAG in the ECM fungal community were significantly correlated with the activities of βG, βLU, and NAG in soil, respectively. Finally, we show that converting natural forests to plantations significantly increased the ammonification rate while decreasing the nitrification and mineralization rates. The close relationship between the relative abundance and diversity of the ECM fungal community, ECM communities and soil NAG, and N processes indicated that the changes in soil N dynamic after forest conversion were directly related to the changes in the ECM fungal community. Our results provide insight into soil C and N dynamics mechanisms resulting from forest conversion.

Assessing n-alkane and neutral lipid biomarkers as tracers for land-use specific sediment sources

Sediment fingerprinting (SF) methods using taxonomic-specific biomarkers such as n-alkanes have been successfully used to distinguish sediment sources originating from different land uses at a catchment scale. In this study, we hypothesise that using a combination of soil biomarkers of plant, fungal and bacterial origin may allow greater discrimination between land uses in SF studies. Furthermore, we assess if the inclusion of short chain (shorter than C22) neutral lipid fatty acids (SC-NLFA) improves land use discrimination, considering the Loch Davan catchment (34 km2) in Scotland as a case study. Fatty acids are commonly used to measure abundance and diversity of soil microbial and fungal communities. The spatial distribution of these soil communities has been shown to depend mainly on soil properties and, therefore, soil types and land management practices. The n-alkane and SC-NLFA concentrations and their compound specific stable isotope signatures (CSSI) in four land cover classes (crop land, pasture, forest, and moorland) were determined and their contribution to six virtual sediment mixture samples was modelled. Using a Bayesian un-mixing model, the performance of the combined n-alkane and SC-NLFA biomarkers in distinguishing sediment sources was assessed. The collection of new empirical data and novel combinations of biomarkers in this study found that land use can be distinguished more accurately in organic sediment fingerprinting when combining n-alkanes and SC-NLFA or using SC-NLFA and their CSSI alone. These results suggest that fingerprinting methods using the output of unmixing models could be improved by the use of multiple tracer sets if there is a commensurate way to determine which tracer set provides the “best” capacity for land use source discrimination. This new contribution to the organic sediment fingerprinting field highlights that different combinations of biomarkers may be required to optimise discrimination between soils from certain land use sources (e.g., arable-pasture). The use of virtual mixtures, as presented in this study, provides a method to determine if addition or removal of tracers can improve relative error in source discrimination. Combining biomarkers from different soil communities could have a significant impact on the identification of recent sources of sediment within catchments and therefore on the development of effective management strategies.

Ecological drivers of fine-scale distribution of arbuscular mycorrhizal fungi in a semiarid Mediterranean scrubland.

Arbuscular mycorrhizal (AM) fungi enhance the uptake of water and minerals by the plant hosts, alleviating plant stress. Therefore, AM fungal-plant interactions are particularly important in drylands and other stressful ecosystems. We aimed to determine the combined and independent effects of above- and below-ground plant community attributes (i.e. diversity and composition), soil heterogeneity and spatial covariates on the spatial structure of the AM fungal communities in a semiarid Mediterranean scrubland. Furthermore, we evaluated how the phylogenetic relatedness of both plants and AM fungi shapes these symbiotic relationships. We characterized the composition and diversity of AM fungal and plant communities in a dry Mediterranean scrubland taxonomically and phylogenetically, using DNA metabarcoding and a spatially explicit sampling design at the plant neighbourhood scale. The above- and below-ground plant community attributes, soil physicochemical properties and spatial variables explained unique fractions of AM fungal diversity and composition. Mainly, variations in plant composition affected the AM fungal composition and diversity. Our results also showed that particular AM fungal taxa tended to be associated with closely related plant species, suggesting the existence of a phylogenetic signal. Although soil texture, fertility and pH affected AM fungal community assembly, spatial factors had a greater influence on AM fungal community composition and diversity than soil physicochemical properties. Our results highlight that the more easily accessible above-ground vegetation is a reliable indicator of the linkages between plant roots and AM fungi. We also emphasize the importance of soil physicochemical properties in addition to below-ground plant information, while accounting for the phylogenetic relationships of both plants and fungi, because these factors improve our ability to predict the relationships between AM fungal and plant communities.

Bacillus amyloliquefaciens FG14 as a potential biocontrol strain against rusty root rot of Panax ginseng, and its impact on the rhizosphere microbial community

Rusty root rot is the most destructive disease in ginseng production. The bacterial strain FG14 isolated from the rhizosphere of Panax ginseng was characterised as Bacillus amyloliquefaciens. The inhibition rates of the FG14 bacterial suspension against the mycelial growth, spore production and spore germination of Ilyonectria robusta which causes ginseng rusty root rot were all more than 90% at a concentration of 108 cfu/mL. The sterile fermentation broth of strain FG14 also had significant inhibitory ability. The results of plantgrowth promotion showed that the fresh weight and root length of ginseng seedlings treated with 3 × 108 cfu/mL FG14 bacterial suspension were 4.49 times and 2.12 times greater than the seedlings treated with I. robusta. The soil enzyme activities of urease, phosphatase, invertase, and catalase of strain FG14 and the expression of seven lipopeptide biosynthesis genes were up-regulated, and antifungal metabolite production was stable. The diversity and abundance of bacterial and fungal communities in rhizosphere soil changed during different growth stages of ginseng after inoculation with strain FG14. The relative abundance of the Ilyonectria genus was significantly lower than the water control at the leaf spreading stage of P. ginseng. These results indicate the great potential of B. amyloliquefaciens FG14 for use as a biological agent for the green control of ginseng rusty root rot.

Diversity of bacterial and fungal endophytic communities presents in the leaf blades of Sinningia magnifica, Sinningia schiffneri and Sinningia speciosa from different cladus of Gesneriaceae family: A comparative analysis in three consecutive years

Sinningia is a genus of plants of Gesneriaceae family with species native to Brazil and is a source of several classes of bioactive secondary metabolites, such as quinones, terpenoids, flavonoids, and phenylethanoid glycosides. However, the diversity of endophytic microorganisms associated with them and the impact of endophytes on the biosynthesis of bioactive substances is unknown. Therefore, we sought to evaluate the microbial diversity, behavior, and frequency of endophytes in leaves blades of S. magnifica, S. schiffneri, and S. speciosa. These plants were collected in different regions and environments of Brazil and were studied comparatively for three consecutive years. The total DNA obtained from the blades of the plant leaves were sequenced by the Illumina MiSeq platform, followed by bioinformatics analysis to assess the microbial diversity of endophytes associated with each plant species and study year. The results of the taxonomic diversity showed a dynamic microbial community, which contained several bacterial phyla among them, Actinomycetota, Bacteroidota, Bacillota, and Pseudomonadota, and for the fungal phyla Ascomycota and Basidiomycota. Comparing the three years of study, the richness of the genera, over time, was decreasing, with signs of recovery towards the third year. The alpha and beta diversity indices confirm a great phylogenetic richness in the endophytic communities of bacteria and fungi associated with the leaf blades of Sinningia. However, these communities are comparatively little conserved, showing population and taxonomic changes of the microorganisms over time, possibly as a measure of adjustment to environmental conditions, evidencing both its fragility and versatility against the effects of environmental change on its endophytic microbial communities.

Relationships between fungal diversity and fruit quality of Yuluxiang pear during low temperature storage.

Postharvest decay is an urgent problem that affects the storage of pears. Low temperature storage is one of the most important methods to reduce the prevalence of fruit diseases during storage. In this study, the microbial diversity of postharvest Yuluxiang pear (Pyrus × michauxii "Yu Lu Xiang") fruits stored at low temperature for different lengths of times was analyzed. Illumina MiSeq high-throughput sequencing was used to analyze the composition and diversity of fungal communities. The results showed that the fungi within fruit were classified into 6 phyla, 18 classes, 40 orders, 72 families, and 92 genera based on the 97% sequence similarity level. They belonged to 6 phyla, 18 classes, 40 orders, 72 families, and 92 genera. The highest richness of fungi was obtained after 30 d of treatment. The β-diversity index showed that the fungal community composition of these fruit was significantly different at the beginning of storage compared with the different timepoints of samples at low temperature during storage. The comparison of fungal composition at the phylum level indicated that Ascomycota was dominant in the different timepoints of samples at low temperature, while Alternaria was the primary fungus at the genus level. A correlation analysis was used to further explore the correlation between fungi and fruit firmness, titratable acid, and solid soluble contents at low temperatures during storage. Aureobasidium and Didymella positively correlated with the soluble solids and hardness. Phoma positively correlated with the titratable acid, and Aspergillus positively correlated with titratable acid and hardness. This study can guide the industrial production of Yulu pear and also provide a theoretical basis to prevent and control diseases during the storage period of Yulu pear.

Development and Determinants of Topsoil Bacterial and Fungal Communities of Afforestation by Aerial Sowing in Tengger Desert, China.

It was previously reported that afforestation in the desert can help improve soil texture, carbon accumulation, and nutrient status. However, the effects of afforestation on soil microbial composition, diversity, and microbial interactions with soil physicochemical properties have been rarely evaluated quantitatively. Using the method of space-for-time substitutions, we assessed the development and determinants of topsoil bacterial and fungal communities over nearly 40 years of successive afforestation by aerial sowing in Tengger Desert, China. The results showed that afforestation by aerial sowing comprised a considerable proportion of Chloroflexi and Acidobacteria in the bacterial community in addition to the ubiquitous phyla found in desert but had fewer effects on the dominant phyla of the fungal community. At the phylum level, the bacterial community was clearly clustered into two groups. However, it was difficult to differentiate the constituents of the fungal community based on principal coordinate analysis. The richness of the bacterial and fungal communities was significantly higher after five years than at zero years and three years. Additionally, the bacterial community varied parabolically and reached its largest size at twenty years, while the fungal community increased exponentially. Soil physicochemical properties were found to have divergent effects on the abundance and diversity of bacterial and fungal communities, among which salt- and carbon-associated properties (e.g., electrical conductivity, calcium, magnesium, total carbon, and organic carbon) were closely related with the abundance of bacterial-dominant phyla and the diversity of bacteria and fungi, but nutrient-associated properties (e.g., total phosphorus and available phosphorus) were not. The results indicate that afforestation through the salt secretions of plants leaves and carbon inputs from litter promote the development of topsoil bacterial and fungal communities in the desert.

Soil microbial responses to simultaneous contamination of antimony and arsenic in the surrounding area of an abandoned antimony smelter in Southwest China

Soil contamination with heavy metal(loid)s may influence microbial activities in the soil, and consequently jeopardize soil health. Microbial responses to soil contamination play an important role in ecological risk assessment. This study investigated the effect of heavy metal(loid)s contamination on microbial community structure and abundance in the surrounding soil of an abandoned antimony (Sb) smelter in Qinglong county, Guizhou province, Southwest China. A total of 46 soil samples were collected from ten sampling sites (labelled as A–I, and CK) across the study area at depths of 0–2, 2–10, 10–20, 20–30, 30–40, and 40–50 cm. The soil samples were analyzed for total and bioavailable heavy metal(loid) concentrations, bacterial, fungal, and archaeal community structures, diversities, and functions, together with soil basic physicochemical properties. Much greater ecological risk of Sb and arsenic (As) was present in the surface soil (0–2 cm) compared to that in the subsoils. The activities of dominant microorganisms tended to be associated with soil pH and heavy metal(loid)s (i.e., Sb, As, lead (Pb), cadmium (Cd), and chromium (Cr)). Bacteria associated with IMCC26256, Rhizobiales, Burkholderiales, and Gaiellales, and archaea associated with Methanocellales were estimated to be tolerant to high concentrations of Sb and As in the soil. In addition, the magnitude of soil microbial responses to Sb and As contamination was in the order of archaea > bacteria > fungi. In contrast to the negligible response of fungi and negative response of bacteria to Sb and As contamination, there was a strongly positive correlation between archaeal activity and total Sb and As concentrations in the soil. Our findings provide a theoretical basis for the remediation of Sb smelter-affected soil.

Analysis of Fungal Diversity before and after Discoloration of Rubberwood in Xishuangbanna

The discoloration problem of rubber wood caused by the discoloration fungi has caused the degradation of rubber wood and greatly reduced its economic value, and the prevention and control of rubber wood discoloration have become the top priority of basic research on rubber wood protection and modification. To determine the fungal community diversity and dominant groups before and after discoloration of rubber wood, nine rubber wood samples were subjected to ITS sequencing using Illumina high-throughput sequencing technology. The results showed that the detected fungal communities comprised 5 phyla, 18 classes, 58 orders, 137 families, 218 genera, and 297 species. Discoloration of rubber wood is not caused by a single species, with the dominant genera for discolored rubber wood being Huntiella, Ceratocystis, and Acremonium and for undiscolored rubber wood, Phomopsis. Furthermore, the diversity, uniformity of species distribution, and richness of discolored rubber wood were found to be higher than those of undiscolored rubber wood. In conclusion, understanding the change trends in the structure of these fungal communities is essential for studying the biological control of rubberwood discoloration.

Depth-dependent effects of tree species identity on soil microbial community characteristics and multifunctionality

Soil microbes play key roles that support forest ecosystem functioning, while their community characteristics are strongly determined by tree species identity. However, the majority studies primarily focus on soil microorganisms in the topsoil, resulting in limited understanding of the linkages between tree species identity and the microbial communities that inhabit deep soils. Here we investigated the diversity, structure, function, and co-occurrence networks of soil bacterial and fungal communities, as well as related soil physicochemical properties, to a depth of two meters in dryland forests dominated by either Pinus tabuliformis, a native coniferous species, Robinia pseudoacacia, an exotic broadleaf and nitrogen-fixing species, or both. Tree species identity had stronger effects on soil multifunctionality and microbial community structure in the deep layers (80–200 cm) than in the top layers (0–60 cm). In addition, fungal communities were more responsive to tree species identity, whereas bacteria were more sensitive to soil depth. Tree species identity strongly influenced microbial network stability and complexity, with higher quantities in R. pseudoacacia than the other plantations, by affecting microbial composition and their associations. The increased in microbial network complexity and the relative abundance of keystone taxa enhance the soil multifunctionality of microbial productivity, sugar and chitin degradation, and nutrient availability and cycling. Meanwhile, the relative abundance of keystone taxa was more representative of soil multifunctionality than microbial diversity. Our study highlights that tree species identity significantly influences soil microbial community characteristics and multifunctionality, especially in deep soils, which will help us understand soil nutrients processed in plantation forest ecosystem and provide a reference for tree species selection in ecological restoration.

Moso bamboo invasion changes the assembly process and interactive relationship of soil microbial communities in a subtropical broadleaf forest

Moso bamboo (Phyllostachys edulis) invasion into adjacent broadleaf forests has been widely observed across subtropical China, and has induced negative effects on aboveground biodiversity. However, how bamboo invasion influences soil microbial community structure and assembly process remains largely unknown. We investigated the changes in diversity, structure and assembly processes of bacterial and fungal communities in an evergreen broadleaf forest following Moso bamboo invasion. Soil samples were collected from three forests (a pure Moso bamboo forest, an adjacent mixed bamboo-broadleaf forest, and a non-invaded broadleaf forest) along twelve invasion transects. Our results showed that bamboo invasion increased soil pH and decreased the contents of soil organic carbon (SOC), dissolved organic carbon (DOC), total and available nitrogen and phosphorus nutrients. Bamboo invasion significantly increased the diversity indices (i.e., OTU richness and Shannon index) of both bacteria and fungi and changed their community compositions (P < 0.05). Bamboo invasion significantly decreased the relative abundance of Actinobacteria and Basidiomycota whereas increased those of Ascomycota and Mortierellomycota. The co-occurrence network analysis displayed more connected and complex relationships of both bacterial and fungal communities in bamboo forest. Bamboo invasion increased the community-level habitat niche breadths of both bacterial and fungal communities due to increased abundances of generalists. The stochastic process of bacterial and fungal community assembly weakened and the deterministic process enhanced generally as a result of bamboo invasion. The migration rate of bacterial communities (0.615) was higher than that of fungal communities (0.037), indicating that dispersal limitation less affect bacteria taxa. Random forest model demonstrated that DOC content, followed by mineral N, were the most important factors mediating the bacterial and fungal community assembly. Taken together, our results suggest that bamboo invasion strongly altered the assembly of bacterial and fungal communities by regulating the deterministic-stochastic balance, which deepens our understanding of the role of bamboo invasions on ecological processes.

Impacts of agroecological practices on soil microbial communities in experimental open-field vegetable cropping systems.

This study aimed to determine the impact of different agroecological practices on the composition and diversity of edaphic bacterial and fungal communities. We designed two experimental agroecological vegetable cropping systems and analyzed their effects on soil microbial communities by pyrosequencing the 16S and 18S ribosomal RNA genes. Our results highlighted modifications to the Operational Taxonomic Units in both experimental systems compared with bare soil, particularly for the phyla Actinobacteria, Ascomycota, Bacteroidetes, and Mucoromycota. Multidimensional scaling plots based on beta diversity showed a clear distinction between the two experimental systems for fungi, whereas differences were observed between bare soil and the two experimental systems for bacteria. Overall, the agroecological systems enhanced soil microbial diversity. We showed a distinction between the two experimental systems and bare soil, correlated with the high total N and total P contents in the agroecological systems. Both experimental systems promoted soil enrichment with certain essential minerals. The agroecological systems had a positive impact on soil microbial communities, particularly by promoting the development of beneficial soil bacteria like Actinobacteria. In the two experimental systems, changes in the quality and quantity of organic matter (i.e. mulch, vermicompost, plant diversity) could have modified the abundance and diversity of microbial communities.