Fungal Ecology最新文献

Extreme climatic events and related disturbances such as hurricanes are increasingly altering forest ecosystems. How these events impact forest fungal communities is poorly characterized. We examined the effect of a hurricane on mycorrhizal community structure and potential interspecific fungal interactions, inferred from OTU co-occurrences. We characterized the root fungal communities of dual-mycorrhizal plants from nine plots during two consecutive years after a category four hurricane impacted the coastal Mexican Pacific tropical forest in Jalisco. Presence-abundance matrices were used to calculate properties of mycorrhizal networks including nestedness and modularity, and to infer patterns of co-occurrence. One year after the hurricane there was a loss of links between plants and fungi. Increased network modularity and connectivity were observed after two years. We also found that disturbance changed arbuscular mycorrhizal fungal network structure more strongly than ectomycorrhizal fungal networks. Fungal guilds changed their putative interspecific interactions, from mutual exclusion in the first year to a significant increase in co-occurrence of plant pathogens, saprotrophs, and endophytes in the second year. Our results suggest that in the short term, rhizospheric interactions can be resilient to hurricanes, but fungal guilds may have divergent responses.

The Phialocephala fortinii s.l. – Acephala applanata species complex (PAC) is composed of closely related endophytic ascomycetes colonizing roots of coniferous trees. Their means of dispersal and teleomorphic form are still unknown. Accordingly, we focused on vegetative mycelial spread of PAC i) via root contacts from PAC-inoculated to PAC-free saplings, ii) through semi-sterile soil from PAC-colonized to PAC-free saplings (without contact) and iii) through semi-sterile soil from PAC-colonized substrate to PAC-free saplings (without contact). Five PAC strains were selected for the experiment. All three modes of PAC transmission found support and were confirmed by metabarcoding. However, transmission via root contact was found to be the most successful. Growth of PAC through soil was also observed whereby transmission from PAC-colonized substrate to PAC-free saplings was more frequent than transmission from PAC-colonized to PAC-free saplings. The transmission rates depended on the PAC strain. Overall, we found support for vegetative transmission of PAC via root contact and active mycelial spread through semi-sterile soil.

Desertification-control policies have been applied in the Mu Us Desert since the 1950s. The landscape there is characterized by patches of shrub plants and well-developed lichen and moss crusts, some covered by shrub canopies and some in interspace soils. Little is known about how shrub cover and biocrusts shape soil fungal community structure in this ecosystem. Using high-throughput amplicon sequencing, the effects of biocrust types and shrub cover on soil fungal communities were analyzed. The results showed that biocrust types were more important than shrub cover in affecting soil properties and shaping soil fungal communities. Among all the measured soil properties, significant effects of shrub cover on soil pH and available P were observed. Biocrust types had significant effects on soil total organic carbon, C:N, and C:P ratios. Fungal taxa relating to plant pathogens and formation of lichens, (e.g., the Eurotiomycetes and Dothideomycetes and the of genera Endocarpon and Knufia) were dominant across biocrust types and shrub cover. Furthermore, although relative abundances of dominant fungal taxa were statistically similar among microhabitats, abundances of lichenized and pathogenic fungi differed significantly among biocrust types, with the former showing higher abundances in lichen crusts, and the latter exhibiting higher abundances in moss crosts. Soil total nitrogen and C:N were correlated with fungal community structure. Our results highligh the dominant role of biocrust types over shrub cover in shaping soil fungal communities in the Mu Us Desert. With the succession from lichen to moss crusts, increasing N limitation (soil TOC:TN ratio) may drive higher abundances of pathogenic fungi in lichen crusts and fewer lichenized fungi in moss crusts.

Host phylogenetic relatedness is the most widely accepted factor to explain host-fungus compatibility in ectomycorrhizal (ECM) fungi. The biogeographic similarity between host and fungus has been recently proposed as another important factor. However, as phylogenetically related hosts often have similar biogeography, it remains disputable whether host biogeography is an important determinant of host-fungus compatibility. In the present study, we conducted inoculation tests to evaluate the colonization ability of 13 ECM fungal operational taxonomic units (OTUs) which are putatively associated with Quercus serrata (Fagaceae), to three Japanese (Q. serrata, Castanopsis sieblodii [Fagaceae], and Pinus thunbergii [Pinaceae]) and two Australian species (Eucalyptus globulus and E. camaldulensis [Myrtaceae]). The colonization pattern of the inoculated OTUs could be classified into two categories: ECM fungi that associated only with Fagaceae and those associated with Japanese hosts. Eucalyptus was less able to associate with the inoculated fungi than P. thunbergii. Our results support the notion that the biogeographic similarity between fungi and hosts as well as host phylogeny can explain host-fungus compatibility.

Vegetation changes in a warming Arctic may affect plant-associated soil microbial communities with possible consequences for the biogeochemical cycling of carbon (C) and nitrogen (N). In a sub-arctic tundra heath, we factorially removed plant species with ecto- and ericoid mycorrhizal associations. After two years, we explored how mycorrhizal type-specific plant removal influences microbial communities, soil and microbial C and N pools, and extracellular enzymatic activities. Removal of ecto- and ericoid mycorrhizal plants did not change the soil fungal or bacterial community composition or their extracellular enzyme activities. However, ericoid plant removal decreased microbial C:N ratio, suggesting a stoichiometric effect decoupled from microbial community composition. In other words, microbial communities appear to show initial plasticity in response to major changes in tundra vegetation. This highlights the importance of longer-term perspectives when investigating the effects of vegetation changes on biogeochemical processes in Arctic ecosystems.

Fungal secondary metabolites (SMs) have attracted significant attention due to their pharmaceutical applications and negative impact as food contaminants. However, less attention has been paid to understanding the ecological role of SMs for the producer and their natural microbial community. To investigate this, we performed co-cultures of SM deficient mutant strains and wild type fungi isolated from mouldy windfall apples. The competitiveness of Penicillium expansum mutant strains was tested in co-cultures with Monilinia fructigena on apple puree agar. Remarkably, the absence of patulin production in P. expansum lead to a loss of antagonism against M. fructigena, revealing a nuanced ecological role that extends beyond the involvement of patulin in host pathogenicity. Furthermore, chemical analysis revealed biotransformation of patulin by M. fructigena, pointing to a more complex interplay mediated by SMs for fungal species inhabiting the same ecosystem.

Lichens are multi-kingdom symbioses in which fungi, algae and bacteria interact to develop a stable selection unit. In addition to the mycobiont forming the symbiosis, fungal communities associated with lichens represent the lichen mycobiota. Because lichen mycobiota diversity is still largely unknown, we aimed to characterize it in two cosmopolitan lichens, Rhizoplaca melanophthalma and Tephromela atra. The mycobiota were investigated across a broad distribution using both a culture-dependent approach and environmental DNA metabarcoding. The variation of the mycobiota associated with the two lichen species was extremely high, and a stable species-specific core mycobiota was not detected with the methods we applied. Most taxa were present in a low fraction of the samples, and no fungus was ubiquitously present in either lichen species. The mycobiota are thus composed of heterogeneous fungi, and some taxa are detectable only by culture-dependent approaches. We suspect that lichens act as niches in which these fungi may exploit thallus resources and only a few may establish more stable trophic relationships with the major symbiotic partners.

The Chinese caterpillar fungus (CCF, Ophiocordyceps sinensis) is a valuable biological resource found on the Qinghai-Tibet Plateau. The distribution pattern of the CCF and its host insects (Hepialus spp.) and insects’ host plants in response to climate change based on interspecific relationships remains unclear. In this study, we used a MaxEnt model to explore this issue under four climate scenarios. The results showed that the CCF, Hepialus spp., and the high redundancy area of host plants all shared strong similarities in terms of distribution pattern, revealing that the distributions of both the CCF and its host insects depended on high redundancy of host plants. From the Middle Holocene to present and then to 2050, the distribution area suitable for the CCF continues to move and expand to the northwest and to higher elevations. Our models suggest that climate change may contribute to the expansion of the CCF habitat and slow the rapid decrease in the CCF yield resulting from intensive harvesting over recent decades.

In subarctic mountain birch forests, reindeer grazing and moth outbreaks act as important biotic drivers of ecosystem functioning. We investigated how a long-term contrast in reindeer grazing regimes and short-term ungulate exclusion affected soil fungal and bacterial communities in mountain birch forests recovering from a recent moth outbreak. We separately described the impacts on microbial communities for organic and mineral soil layers. Differences in fungal communities were mainly explained by variations between grazing regimes, whereas the four-year exclusion of ungulates had little effect. Soil microbial communities showed a high level of specificity between organic and mineral layers. Our results suggest that long-term grazing may have cascading impacts, especially on ectomycorrhizal fungal communities. In contrast, ericoid mycorrhizal and saprotrophic fungal communities and soil bacterial communities were less affected by grazing and appeared to be more resilient to aboveground herbivory in mountain birch forests recovering from a moth outbreak.

Plant-fungal interactions shape ecosystem dynamics and are increasingly recognized as important in the success of invasive plants. Although diverse fungal endophytes are known to inhabit plants, including grasses, the precise chemical mechanisms through which they influence their hosts remain inadequately understood. We used untargeted metabolomics to characterize substrate use and compound production of three fungal endophytes isolated from an invasive grass, Eragrostis lehmanniana, characterizing the metabolome of these fungal isolates grown alone (axenically) and in the presence of seeds from invasive E. lehmanniana and co-occurring native grasses (E. intermedia, Bouteloua curtipendula, and Leptochloa dubia). We found that each fungal isolate expressed a different metabolic profile in response to Eragrostis seeds, relative to seeds of non-Eragrostis native grasses. Coupled with results of germination trials, these findings suggest that plant-fungal interactions mediated by the fungal metabolome may play a key role in determining the success of a major invasive species.