64 results found
Gomes SIF, Aguirre-Gutierrez J, Bidartondo MI, et al., 2017, Arbuscular mycorrhizal interactions of mycoheterotrophic Thismia are more specialized than in autotrophic plants, NEW PHYTOLOGIST, Vol: 213, Pages: 1418-1427, ISSN: 0028-646X
In general, plants and arbuscular mycorrhizal (AM) fungi exchange photosynthetically fixed carbon for soil nutrients, but occasionally nonphotosynthetic plants obtain carbon from AM fungi. The interactions of these mycoheterotrophic plants with AM fungi are suggested to be more specialized than those of green plants, although direct comparisons are lacking. We investigated the mycorrhizal interactions of both green and mycoheterotrophic plants. We used next-generation DNA sequencing to compare the AM communities from roots of five closely related mycoheterotrophic species of Thismia (Thismiaceae), roots of surrounding green plants, and soil, sampled over the entire temperate distribution of Thismia in Australia and New Zealand. We observed that the fungal communities of mycoheterotrophic and green plants are phylogenetically more similar within than between these groups of plants, suggesting a specific association pattern according to plant trophic mode. Moreover, mycoheterotrophic plants follow a more restricted association with their fungal partners in terms of phylogenetic diversity when compared with green plants, targeting more clustered lineages of fungi, independent of geographic origin. Our findings demonstrate that these mycoheterotrophic plants target more narrow lineages of fungi than green plants, despite the larger fungal pool available in the soil, and thus they are more specialized towards mycorrhizal fungi than autotrophic plants.
Merckx VSFT, Gomes SIF, Wapstra M, et al., 2017, The biogeographical history of the interaction between mycoheterotrophic Thismia (Thismiaceae) plants and mycorrhizal Rhizophagus (Glomeraceae) fungi, JOURNAL OF BIOGEOGRAPHY, Vol: 44, Pages: 1869-1879, ISSN: 0305-0270
AimAchlorophyllous mycoheterotrophic plants and mycorrhizal fungi often have highly specific interactions that potentially limit the plants’ distribution and diversification potential. However, specificity in biotic interactions may differ considerably over a species’ distribution range and therefore interactions need to be studied over their entire range to assess their evolution in space and time. 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
Renny M, Cristina Acosta M, Cofre N, et al., 2017, Genetic diversity patterns of arbuscular mycorrhizal fungi associated with the mycoheterotroph Arachnitis uniflora Phil. (Corsiaceae), ANNALS OF BOTANY, Vol: 119, Pages: 1279-1294, ISSN: 0305-7364
Background and Aims: Arachnitis uniflora is a mycoheterotrophic plant that exploits arbuscular mycorrhizal fungi of neighbouring plants. We tested A. uniflora 's specificity towards fungi across its large latitudinal range, as well as the role of historical events and current environmental, geographical and altitudinal variables on fungal genetic diversity. Methods: Arachnitis 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. uniflora were detected rarely and appear to be facultative associations. 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.
Rimington WR, Pressel S, Field KJ, et al., 2017, Reapprasing the origins of mycorrhizas, Molecular Mycorrhizal Symbiosis, Editors: Martin, Publisher: John Wiley & Sons, Pages: 21-32, ISBN: 9781118951415
Schiebold JM-I, Bidartondo MI, Karasch P, et al., 2017, You are what you get from your fungi: nitrogen stable isotope patterns in Epipactis species, ANNALS OF BOTANY, Vol: 119, Pages: 1085-1095, ISSN: 0305-7364
Background and Aims: Partially mycoheterotrophic plants are enriched in 13 C and 15 N compared to autotrophic plants. Here, it is hypothesized that the type of mycorrhizal fungi found in orchid roots is responsible for variation in 15 N 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. Key Results: The 15 N enrichment of Epipactis species varied between 3·2 ± 0·8 ‰ ( E. gigantea ; rhizoctonia-associated) and 24·6 ± 1·6 ‰ ( E. neglecta ; associated with ectomycorrhizal ascomycetes). Sporocarps of ectomycorrhizal ascomycetes (10·7 ± 2·2 ‰) were significantly more enriched in 15 N than ectomycorrhizal (5·2 ± 4·0 ‰) and saprotrophic basidiomycetes (3·3 ± 2·1 ‰). Conclusions: As hypothesized, it is suggested that the observed gradient in 15 N enrichment of Epipactis species is strongly driven by 15 N abundance of their mycorrhizal fungi; i.e. ɛ 15 N in Epipactis spp. associated with rhizoctonias < ɛ 15 N in Epipactis spp. with ectomycorrhizal basidiomycetes < ɛ 15 N in Epipactis spp. with ectomycorrhizal ascomycetes and basidiomycetes < ɛ 15 N in Epipactis spp. with ectomycorrhizal ascomycetes.
Field KJ, Rimington WR, Bidartondo MI, et al., 2016, Functional analysis of liverworts in dual symbiosis with Glomeromycota and Mucoromycotina fungi under a simulated Palaeozoic CO2 decline, ISME JOURNAL, Vol: 10, Pages: 1514-1526, ISSN: 1751-7362
Most land plants form mutualistic associations with arbuscular mycorrhizal fungi of the Glomeromycota, but recent studies have found that ancient plant lineages form mutualisms with Mucoromycotina fungi. Simultaneous associations with both fungal lineages have now been found in some plants, necessitating studies to understand the functional and evolutionary significance of these tripartite associations for the first time. We investigate the physiology and cytology of dual fungal symbioses in the early-diverging liverworts Allisonia and Neohodgsonia at modern and Palaeozoic-like elevated atmospheric CO2 concentrations under which they are thought to have evolved. We found enhanced carbon cost to liverworts with simultaneous Mucoromycotina and Glomeromycota associations, greater nutrient gain compared with those symbiotic with only one fungal group in previous experiments and contrasting responses to atmospheric CO2 among liverwort-fungal symbioses. In liverwort-Mucoromycotina symbioses, there is increased P-for-C and N-for-C exchange efficiency at 440 p.p.m. compared with 1500 p.p.m. CO2. In liverwort-Glomeromycota symbioses, P-for-C exchange is lower at ambient CO2 compared with elevated CO2. No characteristic cytologies of dual symbiosis were identified. We provide evidence of a distinct physiological niche for plant symbioses with Mucoromycotina fungi, giving novel insight into why dual symbioses with Mucoromycotina and Glomeromycota fungi persist to the present day.
Kowal J, Pressel S, Duckett JG, et al., 2016, Liverworts to the rescue: an investigation of their efficacy as mycorrhizal inoculum for vascular plants, FUNCTIONAL ECOLOGY, Vol: 30, Pages: 1014-1023, ISSN: 0269-8463
1. Pezoloma ericae (D.J. Read) Baral, a widespread mycorrhizal fungus of plants in the Ericales,is known to form intracellular associations with several families of leafy liverworts(Schistochilaceae, Lepidoziaceae, Cephaloziaceae, Cephaloziellaceae) in vitro. The ecologicalsignificance of this link between vascular and non-vascular plants is unknown.2. Fungal symbionts were isolated from rhizoids of the leafy liverworts Cephalozia connivens(Dicks.) Lindb. and C. bicuspidata (L.) Dum. (Cephaloziaceae), as well as from the hair rootsof two dominant ericoid mycorrhiza-forming species of European heathlands, Erica tetralix(L.) and Calluna vulgaris (L.).3. Using pure cultures of P. ericae, we resynthesized liverwort–fungus associations to use colonizedliverworts as inoculum which was applied to substrates supporting the growth of heatherseedlings and cuttings. Effects were quantified using germination, rooting, plant colonization,plant survival under waterlogging stress and growth in height in experimental systems withand without liverworts and/or fungi.4. Fungal symbionts growing from liverwort rhizoids readily colonized the hair roots of ericaceousplants to form typical ericoid mycorrhizas.5. The presence of inoculum-bearing liverworts led to significant increases in plant growth.Erica tetralix was more responsive to inoculation than C. vulgaris.6. Ericaceous cuttings rooted and survived more successfully when they were coplanted withpreviously colonized liverwort stems.7. We demonstrate, under realistic ecological circumstances, that liverworts can deliver mycorrhizalinoculum and improve the establishment of vascular plants. We propose that by providingsources of mycorrhizal inoculum, symbiotic non-vascular plants can contribute to therestoration of plant communities dominated by Ericales plants. This research leads to broaderknowledge about the function of ericoid mycorrhizas in ecosystems.
Pressel S, Bidartondo MI, Field KJ, et al., 2016, Pteridophyte fungal associations: Current knowledge and future perspectives, JOURNAL OF SYSTEMATICS AND EVOLUTION, Vol: 54, Pages: 666-678, ISSN: 1674-4918
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. Here we provide a critical review of current knowledge of fungal associations across pteridophytes andconsider future directions making recommendations along the way. From a comprehensive survey of the literature,a confused picture emerges: suggestions that members of the Lycopsida harbour Basidiomycota fungi contrastsharply with extensive cytological and recent molecular evidence pointing to exclusively Glomeromycota and/orMucoromycotina associations in this group. Similarly, reports of dark septate, assumingly ascomycetous, hyphae ina range of pteridophytes, advocating a mutualistic relationship, are not backed by functional evidence and thefact that the fungus invariably occupies dead host tissue points to saprotrophy and not mutualism. The bestconclusion that can be reached based on current evidence is that the fungal symbionts of pteridophytes belong tothe two fungal lineages Mucoromycotina and Glomeromycota. Do symbiotic fungi and host pteridophytes engagein mutually beneﬁcial partnerships? To date, only two pioneering studies have addressed this key questiondemonstrating reciprocal exchange of nutrients between the sporophytes of Ophioglossum vulgatum and Osmundaregalis and their fungal symbionts. There is a pressing need for more functional investigations also extending to thegametophyte generation and coupled with in vitro isolation and resynthesis studies to unravel the effect of thefungi on their host.
Spake R, van der Linde S, Newton AC, et al., 2016, Similar biodiversity of ectomycorrhizal fungi in set-aside plantations and ancient old-growth broadleaved forests, BIOLOGICAL CONSERVATION, Vol: 194, Pages: 71-79, ISSN: 0006-3207
Setting aside overmature planted forests is currently seen as an option for preserving species associated with old-growth forests, such as those with dispersal limitation. Few data exist, however, on the utility of set-aside plantations for this purpose, or the value of this habitat type for biodiversity relative to old-growth semi-natural ecosystems. Here, we evaluate the contribution of forest type relative to habitat characteristics in determining species richness and composition in seven forest blocks, each containing an ancient old-growth stand (> 1000 yrs) paired with a set-aside even-aged planted stand (ca. 180 yrs). We investigated the functionally important yet relatively neglected ectomycorrhizal fungi (EMF), a group for which the importance of forest age has not been assessed in broadleaved forests. We found that forest type was not an important determinant of EMF species richness or composition, demonstrating that set-aside can be an effective option for conserving ancient EMF communities. Species richness of above-ground EMF fruiting bodies was principally related to the basal area of the stand (a correlate of canopy cover) and tree species diversity, whilst richness of below-ground ectomycorrhizae was driven only by tree diversity. Our results suggest that overmature planted forest stands, particularly those that are mixed-woods with high basal area, are an effective means to connect and expand ecological networks of ancient old-growth forests in historically deforested and fragmented landscapes for ectomycorrhizal fungi.
Desiro A, Faccio A, Kaech A, et al., 2015, Endogone, one of the oldest plant-associated fungi, host unique Mollicutes-related endobacteria, NEW PHYTOLOGIST, Vol: 205, Pages: 1464-1472, ISSN: 0028-646X
Glomeromycota have been considered the most ancient group of fungi capable of positively interacting with plants for many years. Recently, other basal fungi, the Endogone Mucoromycotina fungi, have been identified as novel plant symbionts, challenging the paradigm of Glomeromycota as the unique ancestral symbionts of land plants. Glomeromycota are known to host endobacteria and recent evidences show that also some Mucoromycotina contain endobacteria. In order to examine similarities between basal groups of plant-associated fungi, we tested whether Endogone contained endobacteria. Twenty-nine Endogone were investigated in order to identify Mollicutes-related endobacteria (Mre). Fruiting bodies were processed for transmission electron microscopy and molecularly investigated using fungal and Mre-specific primers. We demonstrate that Mre are present inside 13 out of 29 Endogone: endobacteria are directly embedded in the fungal cytoplasm and their 16S rDNA sequences cluster together with the ones retrieved from Glomeromycota, forming, however, a separate new clade. Our findings provide new insights on the evolutionary relations between Glomeromycota, Mucoromycotina and endobacteria, raising new questions on the role of these still enigmatic microbes in the ecology, evolution and diversification of their fungal hosts during the history of plant-fungal symbiosis.
Field KJ, Leake JR, Tille S, et al., 2015, From mycoheterotrophy to mutualism: mycorrhizal specificity and functioning in Ophioglossum vulgatum sporophytes, NEW PHYTOLOGIST, Vol: 205, Pages: 1492-1502, ISSN: 0028-646X
Mycorrhizal functioning in the fern Ophioglossum is complex and poorly understood. It is unknown whether mature O. vulgatum sporophytes form mutualistic associations with fungi of the Glomeromycota and with what specificity. Are green sporophytes able to 'repay' fungal carbon (C) invested in them by mycorrhizal partners during the initially heterotrophic gametophyte and early sporophyte stages of the lifecycle? We identified fungal partners of O. vulgatum sporophytes using molecular techniques and supplied them with (33) P-orthophosphate and O. vulgatum sporophytes with (14) CO2 . We traced the movement of fungal-acquired nutrients and plant-fixed C between symbionts and analysed natural abundance (13) C and (15) N isotope signatures to assess nutritional interactions. We found fungal specificity of O. vulgatum sporophytes towards a mycorrhizal fungus closely related to Glomus macrocarpum. Our radioisotope tracers revealed reciprocal C-for-phosphorus exchange between fern sporophytes and fungal partners, despite competition from surrounding vegetation. Monocultures of O. vulgatum were enriched in (13) C and (15) N, providing inconclusive evidence of mycoheterotrophy when experiencing competition from the surrounding plant community. We show mutualistic and specific symbiosis between a eusporangiate fern and fungi of the Glomeromycota. Our findings suggest a 'take now, pay later' strategy of mycorrhizal functioning through the lifecycle O. vulgatum, from mycoheterotrophic gametophyte to mutualistic aboveground sporophyte.
The domination of the landmasses of Earth by plants starting during the Ordovician Period drastically altered the development of the biosphere and the composition of the atmosphere, with far-reaching consequences for all life ever since. It is widely thought that symbiotic soil fungi facilitated the colonization of the terrestrial environment by plants. However, recent discoveries in molecular ecology, physiology, cytology, and paleontology have brought into question the hitherto-assumed identity and biology of the fungi engaged in symbiosis with the earliest-diverging lineages of extant land plants. Here, we reconsider the existing paradigm and show that the symbiotic options available to the first plants emerging onto the land were more varied than previously thought.
Hynson NA, Bidartondo MI, Read DJ, et al., 2015, Are there geographic mosaics of mycorrhizal specificity and partial mycoheterotrophy? A case study in Moneses uniflora (Ericaceae)., New Phytol, Vol: 208, Pages: 1003-1007, ISSN: 0028-646X
Liebel HT, Bidartondo MI, Gebauer G, et al., 2015, Are carbon and nitrogen exchange between fungi and the orchid Goodyera repens affected by irradiance?, ANNALS OF BOTANY, Vol: 115, Pages: 251-261, ISSN: 0305-7364
BACKGROUND AND AIMS: The green orchid Goodyera repens has been shown to transfer carbon to its mycorrhizal partner, and this flux may therefore be affected by light availability. This study aimed to test whether the C and N exchange between plant and fungus is dependent on light availability, and in addition addressed the question of whether flowering and/or fruiting individuals of G. repens compensate for changes in leaf chlorophyll concentration with changes in C and N flows from fungus to plant. METHODS: The natural abundances of stable isotopes of plant C and N were used to infer changes in fluxes between orchid and fungus across natural gradients of irradiance at five sites. Mycorrhizal fungi in the roots of G. repens were identified by molecular analyses. Chlorophyll concentrations in the leaves of the orchid and of reference plants were measured directly in the field. KEY RESULTS: Leaf δ(13)C values of G. repens responded to changes in light availability in a similar manner to autotrophic reference plants, and different mycorrhizal fungal associations also did not affect the isotope abundance patterns of the orchid. Flowering/fruiting individuals had lower leaf total N and chlorophyll concentrations, which is most probably explained by N investments to form flowers, seeds and shoot. CONCLUSIONS: The results indicate that mycorrhizal physiology is relatively fixed in G. repens, and changes in the amount and direction of C flow between plant and fungus were not observed to depend on light availability. The orchid may instead react to low-light sites through increased clonal growth. The orchid does not compensate for low leaf total N and chlorophyll concentrations by using a (13)C- and (15)N-enriched fungal source.
Rimington WR, Pressel S, Duckett JG, et al., 2015, Fungal associations of basal vascular plants: reopening a closed book?, NEW PHYTOLOGIST, Vol: 205, Pages: 1394-1398, ISSN: 0028-646X
Suz LM, Barsoum N, Benham S, et al., 2015, Monitoring ectomycorrhizal fungi at large scales for science, forest management, fungal conservation and environmental policy, ANNALS OF FOREST SCIENCE, Vol: 72, Pages: 877-885, ISSN: 1286-4560
The ICP Forests network can be a platform for large-scale mycorrhizal studies. Mapping and monitoring of mycorrhizas have untapped potential to inform science, management, conservation and policy regarding distributions, diversity hotspots, dominance and rarity, and indicators of forest changes.
Yokoya K, Zettler LW, Kendon JP, et al., 2015, Preliminary findings on identification of mycorrhizal fungi from diverse orchids in the Central Highlands of Madagascar, MYCORRHIZA, Vol: 25, Pages: 611-625, ISSN: 0940-6360
The Orchid flora of Madagascar is one of the most diverse with nearly 1000 orchid taxa, of which about 90% are endemic to this biodiversity hotspot. The Itremo Massif in the Central Highlands of Madagascar with a Highland Subtropical climate range encompasses montane grassland, igneous and metamorphic rock outcrops, and gallery and tapia forests. Our study focused on identifying culturable mycorrhizae from epiphytic, lithophytic, and terrestrial orchid taxa to understand their diversity and density in a spatial matrix that is within the protected areas. We have collected both juvenile and mature roots from 41 orchid taxa for isolating their orchid mycorrhizal fungi (OMF), and to culture, identify, and store in liquid nitrogen for future studies. Twelve operational taxonomic units (OTUs), of three known orchid mycorrhizal genera, were recognized by analysis of internal transcribed spacer (ITS) sequences of 85 isolates, and, by comparing with GenBank database entries, each OTU was shown to have closely related fungi that were also found as orchid associates. Orchid and fungal diversity were greater in gallery forests and open grasslands, which is very significant for future studies and orchid conservation. As far as we know, this is the first ever report of detailed identification of mycorrhizal fungi from Madagascar. This study will help start to develop a programme for identifying fungal symbionts from this unique biodiversity hotspot, which is undergoing rapid ecosystem damage and species loss. The diversity of culturable fungal associates, their density, and distribution within the Itremo orchid hotspot areas will be discussed.
Bateman RM, Rudall PJ, Bidartondo MI, et al., 2014, Speciation via floral heterochrony and presumed mycorrhizal host switching of endemic butterfly orchids on the Azorean archipelago., American Journal of Botany, Vol: 101, Pages: 979-1001, ISSN: 1537-2197
• Premise of the study: Most orchid species native to the Macaronesian islands reflect immigration from western Europe or North Africa followed by anagenesis. The only putative exception is the butterfly orchids (Platanthera) of the Azores, where three species apparently reflect at least one cladogenetic speciation event. This multidisciplinary study explores the origin, speciation, phenotypic, and genotypic cohesion of these Azorean species and their mainland relatives.• Methods: Plants of Platanthera from 30 localities spanning all nine Azorean islands were compared with those of four continental European relatives for 38 morphometric characters; substantial subsets were also analyzed for plastid microsatellites, and for nrITS of both the orchids and their mycorrhizae.• Key results: Although the three Azorean and four mainland species are all readily distinguished morphometrically using several floral characters, and hybridization appears rare, divergence in ITS and especially plastid sequences is small. Despite occupying similar laurisilva habitats, the Azorean species differ radically in the identities and diversity of their mycorrhizal partners; specialism apparently increases rarity.• Conclusions: Although morphological evidence suggests two invasions of the islands from NW Africa and/or SW Europe, ITS data imply only one. As the molecular data are unable to distinguish among the potential mainland ancestors, two scenarios of relationship are explored that imply different ancestors. Both scenarios require both anagenetic and cladogenetic speciation events, involving homoplastic shifts in overall flower size and (often substantial) changes in the relative dimensions of individual floral organs. Limited genotypic divergence among the three species compared with greater phenotypic divergence suggests comparatively recent speciation. Mycorrhizae may be the most critical factor dictating the respective ecological tolerances, and thus the relativ
Field KJ, Rimington WR, Bidartondo MI, et al., 2014, First evidence of mutualism between ancient plant lineages (Haplomitriopsida liverworts) and Mucoromycotina fungi and its response to simulated Palaeozoic changes in atmospheric CO2, New Phytologist, Vol: 205, Pages: 743-756, ISSN: 1469-8137
The discovery that Mucoromycotina, an ancient and partially saprotrophic fungal lineage, associates with the basal liverwort lineage Haplomitriopsida casts doubt on the widely held view that Glomeromycota formed the sole ancestral plant-fungus symbiosis. Whether this association is mutualistic, and how its functioning was affected by the fall in atmospheric CO2 concentration that followed plant terrestrialization in the Palaeozoic, remains unknown. We measured carbon-for-nutrient exchanges between Haplomitriopsida liverworts and Mucoromycotina fungi under simulated mid-Palaeozoic (1500 ppm) and near-contemporary (440 ppm) CO2 concentrations using isotope tracers, and analysed cytological differences in plant-fungal interactions. Concomitantly, we cultured both partners axenically, resynthesized the associations in vitro, and characterized their cytology. We demonstrate that liverwort-Mucoromycotina symbiosis is mutualistic and mycorrhiza-like, but differs from liverwort-Glomeromycota symbiosis in maintaining functional efficiency of carbon-for-nutrient exchange between partners across CO2 concentrations. Inoculation of axenic plants with Mucoromycotina caused major cytological changes affecting the anatomy of plant tissues, similar to that observed in wild-collected plants colonized by Mucoromycotina fungi. By demonstrating reciprocal exchange of carbon for nutrients between partners, our results provide support for Mucoromycotina establishing the earliest mutualistic symbiosis with land plants. As symbiotic functional efficiency was not compromised by reduced CO2 , we suggest that other factors led to the modern predominance of the Glomeromycota symbiosis.
Schoch CL, Robbertse B, Robert V, et al., 2014, Finding needles in haystacks: linking scientific names, reference specimens and molecular data for Fungi, Database, Vol: 2014, Pages: bau061-bau061, ISSN: 0162-4105
DNA phylogenetic comparisons have shown that morphology-based species recognition often underestimates fungal diversity. Therefore, the need for accurate DNA sequence data, tied to both correct taxonomic names and clearly annotated specimen data, has never been greater. Furthermore, the growing number of molecular ecology and microbiome projects using high-throughput sequencing require fast and effective methods for en masse species assignments. In this article, we focus on selecting and re-annotating a set of marker reference sequences that represent each currently accepted order of Fungi. The particular focus is on sequences from the internal transcribed spacer region in the nuclear ribosomal cistron, derived from type specimens and/or ex-type cultures. Re-annotated and verified sequences were deposited in a curated public database at the National Center for Biotechnology Information (NCBI), namely the RefSeq Targeted Loci (RTL) database, and will be visible during routine sequence similarity searches with NR_prefixed accession numbers. A set of standards and protocols is proposed to improve the data quality of new sequences, and we suggest how type and other reference sequences can be used to improve identification of Fungi.
Stoeckel M, Tesitelova T, Jersakova J, et al., 2014, Carbon and nitrogen gain during the growth of orchid seedlings in nature, New Phytologist, Vol: 202, Pages: 606-615, ISSN: 1469-8137
For germination and establishment, orchids depend on carbon (C) and nutrients supplied by mycorrhizal fungi. As adults, the majority of orchids then appear to become autotrophic. To compare the proportional C and nitrogen (N) gain from fungi in mycoheterotrophic seedlings and in adults, here we examined in the field C and N stable isotope compositions in seedlings and adults of orchids associated with ectomycorrhizal and saprotrophic fungi. Using a new highly sensitive approach, we measured the isotope compositions of seedlings and adults of four orchid species belonging to different functional groups: fully and partially mycoheterotrophic orchids associated with narrow or broad sets of ectomycorrhizal fungi, and two adult putatively autotrophic orchids associated exclusively with saprotrophic fungi. Seedlings of orchids associated with ectomycorrhizal fungi were enriched in (13) C and (15) N similarly to fully mycoheterotrophic adults. Seedlings of saprotroph-associated orchids were also enriched in (13) C and (15) N, but unexpectedly their enrichment was significantly lower, making them hardly distinguishable from their respective adult stages and neighbouring autotrophic plants. We conclude that partial mycoheterotrophy among saprotroph-associated orchids cannot be identified unequivocally based on C and N isotope compositions alone. Thus, partial mycoheterotrophy may be much more widely distributed among orchids than hitherto assumed.
Suz LM, Barsoum N, Benham S, et al., 2014, Environmental drivers of ectomycorrhizal communities in Europe's temperate oak forests, Molecular Ecology, Vol: 23, Pages: 5628-5644, ISSN: 1365-294X
Ectomycorrhizal fungi are major ecological players in temperate forests but they are rarely used in measures of forest condition because large-scale, high-resolution, standardized and replicated belowground data is scarce. We carried out an analysis of ectomycorrhizas at 22 intensively-monitored long-term oak plots, across nine European countries, covering complex natural and anthropogenic environmental gradients. We found that at large scales mycorrhizal richness and evenness declined with decreasing soil pH and root density, and with increasing atmospheric nitrogen deposition. Shifts in mycorrhizas with different functional traits were detected; mycorrhizas with structures specialized for long-distance transport related differently to most environmental variables than those without. The dominant oak-specialist Lactarius quietus, with limited soil exploration, responds positively to increasing N inputs and decreasing pH. In contrast, Tricholoma, Cortinarius and Piloderma species, with medium-distance soil exploration, show a consistently negative response. We also determined N critical loads for moderate (9.5 - 13.5 kg N ha(-1) yr(-1) ) and drastic (17 kg N ha(-1) yr(-1) ) changes in belowground mycorrhizal root communities in temperate oak forests. Overall, we generated the first baseline data for ectomycorrhizal fungi in the oak forests sampled, identified nitrogen pollution as one of their major drivers at large scales, and revealed fungi that individually and/or in combination with others can be used as belowground indicators of environmental characteristics. This article is protected by copyright. All rights reserved.
Desiro A, Duckett JG, Pressel S, et al., 2013, Fungal symbioses in hornworts: a chequered history, Proceedings of the Royal Society B: Biological Sciences, Vol: 280, Pages: 20130207-20130207, ISSN: 0962-8452
Hornworts are considered the sister group to vascular plants, but their fungal associations remain largely unexplored. The ancestral symbiotic condition for all plants is, nonetheless, widely assumed to be arbuscular mycorrhizal with Glomeromycota fungi. Owing to a recent report of other fungi in some non-vascular plants, here we investigate the fungi associated with diverse hornworts worldwide, using electron microscopy and molecular phylogenetics. We found that both Glomeromycota and Mucoromycotina fungi can form symbioses with most hornworts, often simultaneously. This discovery indicates that ancient terrestrial plants relied on a wider and more versatile symbiotic repertoire than previously thought, and it highlights the so far unappreciated ecological and evolutionary role of Mucoromycotina fungi.
Waterman RJ, Klooster MR, Hentrich H, et al., 2013, Species interactions of mycoheterotrophic plants: specialization and its potential consequences., Mycoheterotrophy, Editors: Merckx, New York, Publisher: Springer, Pages: 267-296, ISBN: 978-1-4614-5209-6
Corcoran P, Jacobson DJ, Bidartondo MI, et al., 2012, Quantifying functional heterothallism in the pseudohomothallic ascomycete Neurospora tetrasperma, FUNGAL BIOLOGY, Vol: 116, Pages: 962-975, ISSN: 1878-6146
Neurospora tetrasperma is a pseudohomothallic filamentous ascomycete that has evolved from heterothallic ancestors. Throughout its life cycle, it is predominantly heterokaryotic for mating type, and thereby self-fertile. However, studies of N. tetrasperma have revealed the occasional production of self-sterile asexual and sexual spores of a single-mating type, indicating that it can be functionally heterothallic. Here, we report the extensive sampling and isolation of natural, heterokaryotic, strains of N. tetrasperma from the United Kingdom (UK): 99 strains were collected from Surrey, England, and four from Edinburgh, Scotland. We verified by phylogenetic analyses that these strains belong to N. tetrasperma. We isolated cultures from single germinated asexual spores (conidia) from 17 of these newly sampled UK strains from Surrey, and 16 previously sampled strains of N. tetrasperma from New Zealand (NZ). Our results show that the N. tetrasperma strains from the UK population produced a significantly greater proportion of self-sterile, homokaryotic conidia than the NZ population: the proportion of homokaryotic conidia was 42.6 % (133/312 spores) and 15.3 % (59/386) from the UK and the NZ populations, respectively. Although homokaryons recovered from several strains show a bias for one of the mating types, the total ratio of mat A to mat a mating type in homokaryons (UK: 72/61, NZ 28/31) did not deviate significantly from the expected 1:1 ratio for either of these populations. These results indicate that different populations exhibit differences in their life cycle characteristics, and that a higher degree of outcrossing might be expected from the UK population. This study points to the importance of studying multiple strains and populations when investigating life history traits of an organism with a complex life cycle, as previously undetected differences between populations may be revealed.
Field KJ, Cameron DD, Leake JR, et al., 2012, Contrasting arbuscular mycorrhizal responses of vascular and non-vascular plants to a simulated Palaeozoic CO2 decline, NATURE COMMUNICATIONS, Vol: 3, Pages: 835-835, ISSN: 2041-1723
The arbuscular mycorrhizal (AM) fungal symbiosis is widely hypothesized to have promoted the evolution of land plants from rootless gametophytes to rooted sporophytes during the mid-Palaeozoic (480-360 Myr, ago), at a time coincident with a 90% fall in the atmospheric CO(2) concentration ([CO(2)](a)). Here we show using standardized dual isotopic tracers ((14)C and (33)P) that AM symbiosis efficiency (defined as plant P gain per unit of C invested into fungi) of liverwort gametophytes declines, but increases in the sporophytes of vascular plants (ferns and angiosperms), at 440 p.p.m. compared with 1,500 p.p.m. [CO(2)](a). These contrasting responses are associated with larger AM hyphal networks, and structural advances in vascular plant water-conducting systems, promoting P transport that enhances AM efficiency at 440 p.p.m. [CO(2)](a). Our results suggest that non-vascular land plants not only faced intense competition for light, as vascular land floras grew taller in the Palaeozoic, but also markedly reduced efficiency and total capture of P as [CO(2)](a) fell.
Sommer J, Pausch J, Brundrett MC, et al., 2012, Limited carbon and mineral nutrient gain from mycorrhizal fungi by adult Australian orchids., American Journal of Botany, Vol: 99, Pages: 1133-1145, ISSN: 0002-9122
• Premise of the study: In addition to autotrophic and fully mycoheterotrophic representatives, the orchid family comprises species that at maturity obtain C and N partially from fungal sources. These partial mycoheterotrophs are often associated with fungi that simultaneously form ectomycorrhizas with trees. This study investigates mycorrhizal nutrition for orchids from the southwestern Australian biodiversity hotspot.• Methods: The mycorrhizal fungi of 35 green and one achlorophyllous orchid species were analyzed using molecular methods. Nutritional mode was identified for 27 species by C and N isotope abundance analysis in comparison to non-orchids from the same habitat. As a complementary approach, (13)CO(2) pulse labeling was applied to a subset of six orchid species to measure photosynthetic capacity.• Key results: Almost all orchids associated with rhizoctonia-forming fungi. Due to much higher than expected variation within the co-occurring nonorchid reference plants, the stable isotope approach proved challenging for assigning most orchids to a specialized nutritional mode; therefore, these orchids were classified as autotrophic at maturity. The (13)CO(2) pulse labeling confirmed full autotrophy for six selected species. Nonetheless, at least three orchid species (Gastrodia lacista, Prasophyllum elatum, Corybas recurvus) were identified as nutritionally distinctive from autotrophic orchids and reference plants.• Conclusions: Despite the orchid-rich flora in southwestern Australia, partial mycoheterotrophy among these orchids is less common than in other parts of the world, most likely because most associate with saprotrophic fungi rather than ectomycorrhizal fungi.
The colonization of land by plants relied on fundamental biological innovations, among which was symbiosis with fungi to enhance nutrient uptake. Here we present evidence that several species representing the earliest groups of land plants are symbiotic with fungi of the Mucoromycotina. This finding brings up the possibility that terrestrialization was facilitated by these fungi rather than, as conventionally proposed, by members of the Glomeromycota. Since the 1970s it has been assumed, largely from the observation that vascular plant fossils of the early Devonian (400 Ma) show arbuscule-like structures, that fungi of the Glomeromycota were the earliest to form mycorrhizas, and evolutionary trees have, until now, placed Glomeromycota as the oldest known lineage of endomycorrhizal fungi. Our observation that Endogone-like fungi are widely associated with the earliest branching land plants, and give way to glomeromycotan fungi in later lineages, raises the new hypothesis that members of the Mucoromycotina rather than the Glomeromycota enabled the establishment and growth of early land colonists.
Hardwick KA, Fiedler P, Lee LC, et al., 2011, The Role of Botanic Gardens in the Science and Practice of Ecological Restoration, CONSERVATION BIOLOGY, Vol: 25, Pages: 265-275, ISSN: 0888-8892
Many of the skills and resources associated with botanic gardens and arboreta, including plant taxonomy, horticulture, and seed bank management, are fundamental to ecological restoration efforts, yet few of the world's botanic gardens are involved in the science or practice of restoration. Thus, we examined the potential role of botanic gardens in these emerging fields. We believe a reorientation of certain existing institutional strengths, such as plant-based research and knowledge transfer, would enable many more botanic gardens worldwide to provide effective science-based support to restoration efforts. We recommend botanic gardens widen research to include ecosystems as well as species, increase involvement in practical restoration projects and training practitioners, and serve as information hubs for data archiving and exchange.
Pennington HG, Bidartondo MI, Barsoum N, et al., 2011, A few exotic mycorrhizal fungi dominate eucalypts planted in England, FUNGAL ECOLOGY, Vol: 4, Pages: 299-302, ISSN: 1754-5048
Eucalypts have been planted widely outside of their native habitat for the purposes of commercial forestry. Mycorrhizal fungi are known to have spread with these trees around the world but little is known of the degree to which pre-existing mutualistic associations are maintained, or new associations are formed with Eucalyptus spp. outside of their native range. Molecular methods were used in this study to assess ectomycorrhizal communities colonising eucalypts in England. Our analyses revealed that only a dozen, mainly exotic, fungi were associated with eucalypts and that these mycorrhizal communities were dominated by a Laccaria sp. (C) 2011 Elsevier Ltd and The British Mycological Society. All rights reserved.
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