Background and Aims: The rhizoids of leafy liverworts Jungermanniales, Marchantiophyta are commonly colonized by the ascomycete fungus Pezoloma ericae. These associations are hypothesized to be functionally analogous to the ericoid mycorrhizas ErMs formed by P.
Here, we test whether associations between the leafy liverwort Cephalozia bicuspidata and P. Methods: We measured movement of phosphorus and carbon between C.
We also measured leafy liverwort growth, with and without P. Key Results: We present the first demonstration of nutritionally mutualistic symbiosis between a non-vascular plant and an ErM-forming fungus, showing transfer of fungal-acquired P to the liverwort and of liverwort-fixed C to the fungus alongside increased growth in fungus-colonized liverworts.
Conclusions: Thus, this ascomycete-liverwort symbiosis can now be described as mycorrhiza-like, providing further insights into ericoid mycorrhizal evolution and adding Ascomycota fungi to mycorrhizal fungal groups engaging in mutualisms with plants across the land plant phylogeny. It has long been postulated that symbiotic fungi facilitated plant migrations onto land through enhancing the scavenging of mineral nutrients and exchanging these for photosynthetically fixed organic carbon. Today, land plant-fungal symbioses are both widespread and diverse. Recent discoveries show that a variety of potential fungal associates were likely available to the earliest land plants, and that these early partnerships were probably affected by changing atmospheric CO2 concentrations.
Here, we evaluate current hypotheses and knowledge gaps regarding early plant-fungal partnerships in the context of newly discovered fungal mutualists of early and more recently evolved land plants and the rapidly changing views on the roles of plant-fungal symbioses in the evolution and ecology of the terrestrial biosphere. Endogonales is a lineage of early diverging fungi within Mucoromycota. Many species in this order produce small sporophores "sporocarps" containing a large number of zygospores, and many species form symbioses with plants.
However, due to limited collections, subtle morphological differentiation, difficulties in growing these organisms in vitro, and idiosyncrasies in their rDNA that make PCR amplification difficult, the systematics and character evolution of these fungi have been challenging to resolve. To overcome these challenges we generated a multigene phylogeny of Endogonales using sporophores collected over the past three decades from four continents.
Our results show that Endogonales harbour significant undescribed diversity and form two deeply divergent and well-supported phylogenetic clades, which we delimit as the families Endogonaceae and Densosporaceae fam.
The family Densosporaceae consists of the genus Densospora,Sphaerocreas pubescens, and many diverse lineages known only from environmental DNA sequences of plant-endosymbiotic fungi. Within Endogonaceae there are two clades. One corresponds to Endogone and includes the type species, E. Species of Endogone are characterized by above- and below-ground sporophores, a hollow and infolded sporophore form, a loose zygosporangial hyphal mantle, homogeneous gametangia, and an enigmatic trophic mode with no evidence of ectomycorrhizal association for most species.
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For the other clade we introduce a new generic name, Jimgerdemannia gen. Members of that genus J. Future studies on Densosporaceae and Endogonaceae will be important for understanding fungal innovations including evolution of macroscopic sporophores and symbioses with pl. Historical datasets of living communities are important because they can be used todocument creeping shifts in species compositions. Such a historical data set exists foralpine fungi. Favre can be regarded as one of the pioneersof alpine fungal ecology not least because he noted location, elevation, geology, andassociated plants during his numerous excursions.
However, some relevant informationis only available in his unpublished field-book. Overall, Favre listed fungal species in26 sampling sites, with 46 species being previously unknown. The analysis of his datarevealed that the macrofungi recorded belong to two major ecological groups, either theyare symbiotrophs and live in ectomycorrhizal associations with alpine plant hosts, or theyare saprotrophs and decompose plant litter and soil organic matter.
The most frequentfungi were members of Inocybe and Cortinarius, which form ectomycorrhizas with Dryasoctopetala or the dwarf alpine Salix species. Results of the latter application revealed, that problems associated with these newtechniques are manifold and species determination remains often unclear.
In conclusion, it can be postulated that new improved databasesare urgently necessary for the near future, partic.
Scots pine Pinus sylvestris is frequently planted as a monoculture, but it is also grown in mixed plantations with other native trees such as pedunculate oak Quercus robur. Both pine and oak form ectomycorrhizas that cover their roots and extend into the soil, facilitating tree water and nutrient uptake in exchange for photosynthetic carbon. Forming the interface between the soil and tree roots, mycorrhizal fungi are key drivers of biogeochemical cycling in terrestrial ecosystems and play an important role in the successful establishment of tree seedlings.
They can, however, be susceptible to changes in the soil environment and in their hosts. Both environment and neighboring hosts affect how fungi colonize roots and may affect their host preference. Despite the importance of mycorrhizal fungi in forest ecosystems, little is known about the biodiversity and functional effects of mycorrhizal communities in mixed compared with monoculture plantations.
Changes in mycorrhizal richness and composition can result in changes in functional groups with consequences for forest ecosystem stability and functioning. We compared pine mycorrhizas in eight mixed plantations of pine and oak and eight pine monocultures in two forests in England, and we investigated the main factors driving their taxonomic and functional composition.
Different environmental factors affected taxonomic and functional composition across stands, indicating functional redundancy. Pine tended to associate with more fungi in the presence of oak, but the abiotic environment exerted a stronger influence than oak presence on pine mycorrhizal diversity. Microbes can have profound effects on their hosts, driving natural selection, promoting speciation and determining species distributions. However, soil-dwelling microbes are rarely investigated as drivers of evolutionary change in plants. We used metabarcoding and experimental manipulation of soil microbiomes to investigate the impact of soil and root microbes in a well-known case of sympatric speciation, the Howea palms of Lord Howe Island Australia.
Whereas H. We suggest a novel explanation for this trade-off. Arbuscular mycorrhizal fungi AMF are significantly depleted in H. This is mirrored by the results of survival experiments, where the sterilization of natural soil reduces Howea fitness in every soil—species combination except H. Furthermore, AMF-associated genes exhibit evidence of divergent selection between Howea species.
These results show a mechanism by which divergent adaptation can have knock-on effects on host—microbe interactions, thereby reducing interspecific competition and promoting the coexistence of plant sister species. Partial mycoheterotrophy PMH is a nutritional mode in which plants utilize organic matter, i. The latter reverses the direction of plant-to-fungus carbon flow as usually assumed in mycorrhizal mutualisms.
Based on significant enrichment in the heavy isotope 13C, a growing number of PMH orchid species have been identified. These PMH orchids are mostly associated with fungi simultaneously forming ectomycorrhizas with forest trees. In contrast, the much more common orchids that associate with rhizoctonia fungi, which are decomposers, have stable isotope profiles most often characterized by high 15N enrichment and high nitrogen concentrations but either an insignificant 13C enrichment or depletion relative to autotrophic plants.http://promotime.md/conspiracies-conspiracy-theories-the.php
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Using hydrogen stable isotope abundances recent investigations showed PMH in rhizoctonia-associated orchids growing under light-limited conditions. Hydrogen isotope abundances can be used as substitute for carbon isotope abundances in cases where autotrophic and heterotrophic carbon sources are insufficiently distinctive to indicate PMH. To determine whether rhizoctonia-associated orchids growing in habitats with high irradiance feature PMH as a nutritional mode, we sampled 13 orchid species growing in montane meadows, four forest orchid species and 34 autotrophic reference species.
Orchid mycorrhizal fungi were identified by DNA sequencing. As expected, we found high enrichments in 2H, 13C, 15N and nitrogen concentrations in the ectomycorrhiza-associated forest orchids, and the rhizoctonia-associated Neottia cordata from a forest site was identified as PMH. Most orchids inhabiting sunny meadows lacked 13C enrichment or were even significantly depleted in 13C relative to autotrophic references. The present study investigates the biogeographical history of the interaction between five closely related mycoheterotrophic Thismia species and arbuscular mycorrhizal fungi over the distribution range of the plant species.
LocationTemperate south-east Australia and New Zealand. MethodsPhylogenetic relationships of Thismia nrITS and mtcob and their arbuscular mycorrhizal fungi partial nrSSU were reconstructed based on data from 65 plant specimens. The diversification times in Thismia were estimated with a Bayesian relaxed clock approach using a Dioscoreales framework nrSSU, mtatp1, mtmatR, mtnad1 b-c.
Ancestral geographical ranges were reconstructed using a maximum likelihood approach. The same approach was used to reconstruct ancestral mycorrhizal associations. ResultsOur analysis shows that Thismia plants have highly specific, phylogenetically conserved and evolutionarily persistent interactions with Rhizophagus fungi. Nevertheless, Thismia was able to diversify and radiate recently due to the wide geographical distribution of the host fungi. In addition, we find that although the mycorrhizal interactions of this clade of mycoheterotrophs are strictly bound to a fungal lineage, host switches remain possible.
Main conclusionsIn this clade of closely related mycoheterotrophs, dependency on highly specific fungal interactions is the result of phylogenetic niche conservatism, acting over at least 12 million years. Nevertheless, plants that are dependent on highly specific fungal interactions have ample opportunities to disperse and radiate over the geographic. Background and AimsArachnitis uniflora is a mycoheterotrophic plant that exploits arbuscular mycorrhizal fungi of neighbouring plants.
We tested A. MethodsArachnitis uniflora mycorrhizas were sampled at 25 sites. Fungal phylogenetic relationships were reconstructed, genetic diversity was calculated and the main divergent lineages were dated. Phylogeographical analysis was performed with the main fungal clade.
Fungal diversity correlations with environmental factors were investigated. Key Results Glomeraceae fungi dominated, with a main clade that likely originated in the Upper Cretaceous and diversified in the Miocene. Two other arbuscular mycorrhizal fungal families not previously known to be targeted by A.
High genetic diversity, found in Bolivia and both northern and southern Patagonia, was correlated with temperature, rainfall and soil features. Conclusions Fungal genetic diversity and its distribution can be explained by the ancient evolutionary history of the target fungi and by micro-scale environmental conditions with a geographical mosaic pattern.
Lynn Margulis and the endosymbiont hypothesis: 50 years later
Background and Aims: Partially mycoheterotrophic plants are enriched in 13C and 15N compared to autotrophic plants. Here, it is hypothesized that the type of mycorrhizal fungi found in orchid roots is responsible for variation in 15N enrichment of leaf tissue in partially mycoheterotrophic orchids. Methods: The genus Epipactis was used as a case study and carbon and nitrogen isotope abundances of eight Epipactis species, fungal sporocarps of four Tuber species and autotrophic references were measured. Mycorrhizal fungi were identified using molecular methods.
Stable isotope data of six additional Epipactis taxa and ectomycorrhizal and saprotrophic basidiomycetes were compiled from the literature. Conclusions: As hypothesized, it is suggested that the observed gradient in 15N enrichment of Epipactis species is strongly driven by 15N abundance of their mycorrhizal fungi; i. Current understanding of the nature and function of fungal associations in pteridophytes is surprisinglypatchy given their key evolutionary position, current research foci on other early-branching plant clades, and majorefforts at unravelling mycorrhizal evolution and the mechanisms underlying this key interaction between plants andfungi.
This article has been cited by other articles in PMC. Footnotes DOI: New York: Oxford University Press; Trends Genet. Mitochondrial genomes: anything goes. Strikingly bacteria-like and gene-rich mitochondrial genomes throughout jakobid protists. Genome Biol Evol. The simultaneous symbiotic origin of mitochondria, chloroplasts, and microbodies. Ann NY Acad Sci. The endosymbiont hypothesis revisited. Int Rev Cytol. Mitochondrial evolution. Cold Spring Harb Perspect Biol. Has the endosymbiont hypothesis been proven?
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