Fungal Ecology最新文献

We used five mature Picea abies continuously labeled with ¹³C-depleted CO₂ in a broadleaf-dominated Swiss forest to assess the spatial extent and lag time of carbon fluxes to ectomycorrhizal fungi differing in hyphal development and host association. We traced labeled carbon into ectomycorrhizal sporocarps collected for two seasons at different distances from labeled Picea. Picea-derived photosynthate reached conifer-specific sporocarps up to 6–12 m away and reached other sporocarps only 0–6 m away. At 0–6 m, genera of lesser hyphal development acquired more Picea-derived photosynthate than those of greater hyphal development, presumably from preferential fungal colonization of inner root zones by the former genera. Correlations of sporocarp δ¹³C with daily solar radiation integrated for different periods indicated that carbon fluxes from Picea to sporocarps peaked 17–21 days after photosynthesis. Thus, these results provided rough estimates of the spatial extent and temporal lags of carbon transfer from Picea to ectomycorrhizal fungi.

The relationship between aquatic environmental DNA (eDNA) assemblages in rivers and the surrounding terrestrial fungal communities has been poorly investigated. Here, we focused on fungi that form soft sporocarps (soft fungi). Two years of sporocarp and aquatic eDNA sampling were conducted at a fragmented forest site, and the soft-fungal assemblages and their temporal dynamics were compared between these two sample types. Aquatic eDNA yielded approximately 1.5 times the operational taxonomic units (OTUs) compared to sporocarps and covered approximately half of the OTUs from sporocarp samples. Lineages that seldom form sporocarps or form inconspicuous sporocarps were successfully detected from aquatic eDNA. Although the OTU composition differed between sporocarp and aquatic eDNA, their temporal dynamics were similar, with both showing a 1-year periodicity. Aquatic eDNA provides insights into fungal diversity and temporal dynamics, but does not fully reflect terrestrial fungi diversity.

Epichloë coenophiala forms aboveground symbiotic relationships with tall fescue (Festuca arundinacea) and provides the host with better fitness. This study investigated the effects of endophyte symbiosis on carbon mineralization in soil. Two soils were amended with endophyte-infected (E+) or endophyte-free (E−) residues of two tall fescue genotypes. At the end of the experiment, CO₂ evolution rates were monitored to quantify the mineralized carbon. The indices of carbon mineralization were significantly greater (LSD, P < 0.05) in the E−compared to E+ plant residue treated soils. Cellulose, hemicellulose, lignin contents, C:N and lignin:N ratios were significantly greater (LSD, P < 0.05) in soils with the E⁺ residues than in those with E⁻ residues. Additionally, the E+ plant residues consistently contained significantly less N (LSD, P < 0.05). Overall, it is concluded that grass-endophyte symbiosis results in the production of less biodegradable plant residues, in turn reducing the residue biodegradability and promoting greater C accumulation in the soils.

Arbuscular mycorrhizal fungi (AMF) are considered ecosystem engineers, but the interactions of their mycelium with their immediate surroundings are largely unknown. In this study, we used microfluidic chips, simulating artificial soil structures, to study foraging strategies and habitat modification of Rhizophagus irregularis symbiotically associated to carrot roots. AMF hyphae foraged over long distances in nutrient-void spaces, preferred straight over tortuous passages, anastomosed and showed strong inducement of branching when encountering obstacles. We measured bi-directional transport of cellular content inside active hyphae and documented strategic allocation of biomass within the mycelium via cytoplasm retraction from inefficient paths. R. irregularis modified pore-spaces in the chips by clogging pores with irregularly shaped spores. We suggest that studying AMF hyphal behaviour in spatial settings can explain phenomena reported at bulk scale such as AMF modification of water retention in soils. The use of microfluidic soil chips in AMF research opens up novel opportunities to study their ecophysiology and interactions with both biotic and abiotic factors.

The European Alps are experiencing more than twice the increase in air temperature observed in the rest of the world. Thus, the treeline ecotone, and the unique habitats above it, offer a preview of drastic changes in plant and animal communities. However, our knowledge about climate change impacts on microbial diversity belowground is scarce. Here we investigate how upslope shift of the treeline ecotone, associated with changes in soil nutrient content, temperature and precipitation, will influence alpine ectomycorrhizal (EM) communities of Dryas octopetala, Bistorta vivipara and Salix herbacea across different habitat types in the Alps. We also assessed the degree of EM community taxonomic composition turnover in these habitats across three different climatic projections for 2040 and 2070. Our results indicate that the specialized EM fungal communities from snowbed habitats will be mostly negatively influenced under the current trajectory of environmental shifting predicted for the region. In contrast, fungi from the treeline ecotone, having wider niches, will be positively influenced by future climate and extend upwards. In addition, our predictions of EM community turnover for putative future climatic scenarios revealed high rates of turnover across the entire alpine region. This, together with glacier retreats, will aid colonization of alpine snowbed habitats by new EM plants and associated fungi, bringing additional pressures on local mycorrhizas and likely leading to fungal species extinctions.

Nitrogen (N) addition not only promotes the restoration of degraded grasslands, but also threatens ecosystem functioning through the loss of species richness. Thus, a deep understanding of the effect of N addition on the richness of key organisms in restored grasslands is critical to sustainably restoring degraded grasslands. We conducted a 4-year N addition experiment to investigate the response of both plant and arbuscular mycorrhizal (AM) fungal richness to the combined addition of ammonium (Am) and nitrate (Ni) in a revegetated grassland rehabilitated (with a focus on restoration) on the Qinghai–Tibet Plateau. Both nitrogen forms were added at three levels: 0, 10, and 20 g N m⁻² year⁻¹. By itself, Ni addition of 20 g N m⁻² year⁻¹ (Ni20) reduced both plant and AM fungal richness, while Am addition of 20 g N m⁻² year⁻¹ (Am20) had no significant effect on them. However, when Ni and Am were combined, only Ni20 plus Am20 among all combinations reduced both plant and AM fungal richness. Both soil nitrate-N and plant species richness jointly drove changes in AM fungal richness, but plant species richness was the main factor affecting AM fungal richness under N addition. Our results suggest that minimizing the loss of AM fungi caused by plant species loss resulting from N addition is a key means to sustainably restore degraded grasslands.

Complex interactions involving soil physicochemical parameters and plant-associated microbial communities determine crop health. In Vietnam, this process is poorly understood in the context of black pepper production. Specifically, there is a dearth of information for improving the suppression of pathogenic fungi. Understanding the environmental dynamics influencing the distribution of these pathogens would facilitate the development and use of biological agents in black pepper pathogen management. Here, the molecular profiles of fungal communities from the rhizosphere of healthy and unhealthy Vietnamese black pepper orchards and their relationships were determined. Additionally, co-occurrence analyses with a previously constructed bacterial dataset identified taxa indicative of soil suppression. Alpha diversity of total fungi was influenced by only environmental factors, while that of arbuscular mycorrhizal fungi was more responsive to orchard health state. Glomus sp., Rhizophagus sp., Purpureocillium sp. and Plectosphaerella sp. were the most responsive genera to orchard health state. Potential fungal pathogens were more prevalent in the unhealthy orchards. Co-occurrence network analyses revealed that unhealthy orchards were less connected, had longer path distance and were missing putative pathogen-to-biocontrol interactions common in the healthy orchards. Soil electrical conductivity and potassium may be key factors in differentiating fungal communities of unhealthy from healthy orchards. This work highlights important microbial species and environmental considerations critical to improved black pepper management strategies.

Epiphytic lichens are considered sensitive indicators of environmental change. Excess water is known to depress their photosynthesis, but the effect of long-lasting rain on species richness of epiphytic lichens is rarely reported. By annually repeated records of macrolichen species richness on tree trunks over a period of 33 years that included one long rainy season in year 2000, a strong decline in macrolichen richness on tree trunks was detected after the unusually wet autumn. Afterwards, the lichen richness slowly recovered, but had not yet fully recovered 19 years after the dieback. Thereby, long rainy periods can cause lasting depression in epiphytic lichen richness, and continuous rain should be considered a possible threat to lichens in regions like northern Europe where global change predicts enhanced rainfall frequency.

Understanding the effects of windstorm disturbances on soil communities is of pivotal importance. Oomycete communities host some species of plant pathogens, which might affect the forest regeneration after the disturbance. Here, we sampled a large area to compare three habitats (e.g., windfall, old clearings, and undisturbed spruce forest) along a gradient of elevation and slope. We used an eDNA metabarcoding approach targeting the rps10 gene. Our results showed that both wind disturbance and underlying topography can influence the richness of oomycetes. Higher richness of oomycetes was found in disturbed sites and high steepness. We did not find differences in community composition among the different habitat types at the landscape scale. However, we found significant differences among drainage basins at larger spatial scale. Our work contributed to the understanding of the oomycete communities in Norway spruce forests affected by wind disturbance.

Through species-specific effects on plants, pathogens play a key role in structuring plant communities. A change in abiotic context, such as those mediated by climate change, may alter plant communities through changes in the specificity of plant-pathogen interactions. To test how water availability influenced the specificity of plant-pathogen interactions, we grew paired congeners of three native and three nonnative coastal prairie plant species with or without a pathogenic soil fungus, Fusarium incarnatum-equiseti species complex 6 b, under low, average, and high water treatments. Across the plant species tested, the Fusarium treatment had stronger negative and species-specific effects on plant biomass at high water availability than low water availability. If generalizable, our results suggest that stronger and more species-specific pathogen effects could drive changes in plant community composition in wetter conditions, but plant-pathogen interactions may be less important for plant community structure in drier conditions.