Fungal Ecology最新文献

Soil-borne fungal plant pathogens pose great threats to agricultural productivity and native ecosystems. However, the roles of niche breadth and land-use types in regulating the response of soil-borne fungal plant pathogens to temperature changes largely remain unclear. Here, we surveyed soil pathogens from different valleys where croplands, grasslands, and woodlands scattered in mosaic patterns. We found that pathogen richness increased with increasing temperature in grasslands but not in croplands and woodlands. After classifying the pathogens based on temperature niche, we found that the richness of specialists was sensitive to temperature changes and increased with increasing temperature in grasslands and croplands. By contrast, the richness of neutrals (those taxa not defined as generalists or specialists) did not change with temperature gradients regardless of land-use types. Additionally, pathogens were more abundant and diverse in croplands than those in grasslands and woodlands, and this pattern persisted across the temperature gradient. Our results provide evidence that temperature change and land use types could additively affect the diversity of plant pathogens in soils. This work advances our understanding of how niche breadth affects the response of pathogens to temperature, highlighting the importance of climate change and land use in regulating the abundance and diversity of pathogens.

The slime mold Physarum polycephalum is an amoebozoa that grows forming a cytoplasm network that adapts its geometry to external stimuli. The cytoplasm is made of ectoplasm tubes in which the endoplasmic fluid flows. Endoplasmic flow is due to the rhythmic contraction of the actomyosin fibers of the ectoplasm, which induces a peristaltic wave that can be tracked through the spatiotemporal variations of the tube diameters. Slime mold behavior depends on many periodic modes of tube diameter variation, which is believed to allow a smooth transition between migration directions. Physarum polycephalum can solve mazes and grow optimal networks to solve traveling salesman and Steiner tree problems. Slime mold network dynamics have been modeled through cell automata and stochastic approaches, as well as fluid flow equations, electronic analogs, and multi-agent systems. Here, we examine the modeling strategies available to date to simulate flow-network adaptation in slime molds. However, we found no theoretical framework that can properly predict the evolution of the network as it morphs from an initial configuration to a pseudo-asymptotic optimum or explain the physical phenomena that drive endoplasmic flow or memory encoding at the scale of the entire network. Multi-frame object tracking by k-partite graphs holds promise for slime mold network analysis and tracking, whereas deep learning could be used to classify sequences of latent features to help characterize the behavior of Physarum polycephalum. The combination of the two could pave the way to a new class of predictive behavior models for slime molds.

All cells generate electrical energy derived from the movements of ions across membranes. In animal neurons, action potentials play an essential role in the central nervous system. Plants utilize a variety of electrical signals to regulate a wide range of physiological processes, including wound responses, mimosa leaf movements, and cell turgor changes, such as those involved in stomatal movements. Although fungal hyphae exhibit electrical fluctuations, their regulatory role(s), if any, is still unknown. In his paper “Language of fungi derived from their electrical spiking activity”, Andrew Adamatzky, based on a quantitative analysis of voltage fluctuations in fungal mycelia, concludes that the patterns of electrical fluctuations he detects can be grouped into “words” analogous to those found in human languages. He goes on to speculate that this “fungal language” is used “to communicate and process information” between different parts of the mycelium. Here we argue on methodological grounds that the presumption of a fungal language is premature and unsupported by the evidence presented, that the voltage fluctuations he detects are likely to originate as nonbiological noise and experimental artifacts, and that the measured electrical patterns show no similarity to any properties of human language.

In recent decades bark beetle outbreaks have caused high mortality in natural mountain Picea abies forests in Central Europe. This study evaluated factors affecting seedling establishment of P. abies by focusing on the role of fungal communities in decaying logs, which is an important regeneration microsite. At the control site, which was affected by lower severity disturbance, well decayed logs with moss and vegetation cover hosted many seedlings. At the disturbed site, which experienced high mortality by bark beetles, greater canopy openness suppressed vegetation on logs and lowered seedling density. Additionally, the presence of a white rot basidiomycete Phellopilus nigrolimitatus was positively associated with seedling density. In contrast, the presence of a brown rot basidiomycete Fomitopsis pinicola was negatively associated with seedling density. The relationships between these decomposer fungi and seedling density might be partly attributed to changes in wood chemical properties and associated mycorrhizal and pathogenic fungi.

Interactions among wood-decay fungi can have a profound effect on fungal community composition, decay rates and ultimately the chemical composition of the material remaining after the decay process. Interspecific interactions among fungi as they decay wood have been well-studied but almost nothing is known about the effect of intraspecific interactions between individual genets on the decay process. In this study we examine the effect of both intra- and interspecific competition on wood mass-loss for five species of wood-decay fungi: Cerrena unicolor, Fuscoporia gilva, Irpex lacteus, Stereum ostrea and Trametes versicolor. Four of the five species studied showed a significant increase in mass loss when five individual isolates (genets) of the same species simultaneously colonized aspen test wafers in vitro. The dynamics of interspecific interactions were also significantly impacted by the presence of multiple genets of each species. Taken together, these results demonstrate that intraspecific interactions can change the outcome of interspecific interactions and thus the functioning of the overall community.

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.