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Phylogenetic position of an arbuscular mycorrhizal fungus, Acaulospora gerdemannii, and its synanamorph Glomus leptotichum, based upon 18S rRNA gene sequence
Abstract
We examined the phylogenetic position of an arbuscular mycorrhizal fungus which produces two types of spore,Acaulospora gerdemannii andGlomus leptotichum, based upon the DNA sequence of the 18S rRNA gene. DNA was extracted separately from bothGlomus-like orAcaulospora-like spores and partial 5′-terminus segments of 18S rRNA gene were amplified by the PCR method. Several clones derived from
each spore type were sequenced and compared. The sequences from both spore types agreed well, confirming that these morphologically
different spores were formed by the same fungus. Nucleotide substitutions were found among several clones, suggesting polymorphism
of the rRNA gene in glomalean fungi. Further phylogenetic analysis based upon the whole sequence of the 18S rRNA gene showed
thatA. gerdemannii may be within the order Glomales but is far from the fungi that have been analyzed and probably should be in a new family.
... AM fungi are multi-nuclear organisms and often show polymorphisms in their sequence. It is advisable to sequence several clones from fungus and to check the phylogenetic position of the sequence by constructing phylogentic tree if the target genes are located within a reasonable clade of the tree(Sawaki et al. 1998). ...
This biofertilizer manual is the product of the Biofertilizer Project in FNCA (Forum of Nuclear Cooperation in Asia). Eight countries, China, Indonesia, Japan, Korea, Malaysia, Philippines, Thailand, and Viet Nam participate in this project. The Editor-in-Chief is Dr. Pham Van Toan, the Project Leader of Viet Nam. The activities of this project are introduced in FNCA homepage (http://www.fnca.jp/english/index.
html) in English.The biofertilizer manual is written by project members and other experts to share information and experiences of biofertilizer use in Asian countries, their effectiveness, efficient production processes, storage and application on different crops.It has the following chapters: 1) Introduction, 2) General methods to evaluate microbial
activity, 3) Carriers for biofertilizers, 4) Inoculant for biofertilizers including rhizobia, non-symbiotic nitrogen fixers, mycorrhiza, phosphorous solubilizers, and 5) Quality control of biofertilizers, from advanced basic information to practical methods in each participating country.
... Schenck et G.S. Smith. Subsequently, Sawaki et al. (1998) showed, by molecular analysis of spores from single spore isolates, that A. gerdemannii and G. leptotichum were indeed conspecific. This pattern was further confirmed when single spore isolates from both glomoid spores and acaulospores of a newly described species, Ambispora fennica C. Walker, Vestberg et A. Schüßler, grown to maturity, produced both kinds of spores (Walker et al., 2007). ...
Glomeromycotan propagules (spores) are morphologically diverse in the Early Devonian Rhynie chert; however, only relatively few of these fossils have been documented and critically evaluated. This study re-examines propagules previously described informally as ‘reproductive unit 1’, and identified as glomeromycotan acaulospores borne within the neck of a sporiferous saccule. Size and morphology, spore wall structure, and the close association of specimens in land plant axes with small glomoid spores, are solid arguments for affinities of ‘reproductive unit 1’ to the Ambisporaceae (Archaeosporales). Moreover, the acaulospores correspond morphologically to Mycokidstonia sphaerialoides, a Rhynie chert fossil originally interpreted as an ascomycete perithecium that, consequently, is redefined here as a member of the Glomeromycota conspecific with ‘reproductive unit 1’. The diagnosis for M. sphaerialoides is emended to be compliant with glomeromycotan taxonomy; features of the saccule, acaulospore wall, and associated glomoid spores are included. An epitype is also designated. Mycokidstonia sphaerialoides adds to an increasing body of fossil data depicting Devonian Glomeromycota as a diverse fungal lineage which is likely to have been an ecologically important constituent of early terrestrial ecosystems.
... Mycorrhizal plants can absorb and accumulate several times more phosphate from the soil or solution than nonmycorrhizal plants (3). Plants inoculated with endomycorrhiza were be more resistant to some root diseases (4). Mycorrhiza increase root surface area for water and nutrients uptake. ...
Bio-fertilizers have not been exploited in Kenya on tea production despite benefits demonstrated in many crops. The bio-fertilizers are organisms that enrich nutrient soil quality. Plants have beneficial relationships with such organisms. Shubhodoya mycorrhizal bio-fertilizer is a consortium of three different species of Glomus mycorrhizal fungus, produced in laboratory under sterile conditions. They are cultured and used for inoculating seed or soil or both under ideal conditions to increase availability of plant nutrients. A nursery experiment was conducted to evaluate the efficacy of Shubhodaya mycorrhizal bio-fertilizer (SMB) in enhancing growth of two tea clones, TRFK 306 and EPK TN14-3. Different rates of SMB (0.6g, 0.9g, and 1.2g), standard treatment (6g diammonium phosphate) and control (no fertilizer) were laid out in randomized complete block design. Sleeved seedlings with the soil were randomly sampled from the nursery for analysis of soil pH, assessment of growth parameters and mycorrhizal colonization were conducted. Root samples were used to determine dry weight and to conduct assays for VAM infection. The SMB did not have adverse effects on soil pH in the nursery. Plants subjected to the DAP treatment all died after weeks 27. Increasing application of SMB rates and frequency increased shoot growth. SMB at 1.2 g exhibited the lowest shoots dry weight while SMB at 0.6 and 0.9g had the highest. After 62 weeks from planting, there was an abrupt increase in shoot dry weight. Successful colonization of tea roots with inoculation of SMB was also observed. SMB colonized the tea roots an indication that it has potential for exploitation.
... Studies from the last decade thus unequivocally showed that G. pyriformis indeed is a member of the Glomeromycota. Previous sequence analyses (Sawaki et al. 1999;Schüßler 1999;Schüßler et al. 2001a;Redecker et al. 2000b) showed it to be closely related to an AMF forming two different spore morphs, at the time named Acaulospora gerdemannii (synanamorph Glomus leptotichum). Nowadays, the clade containing these lineages is defined as the order Archaeosporales and represents one of the basal main phylogenetic lineages in the Glomeromycota (Schüßler et al. 2001b). ...
The only known endosymbiosis with cyanobacteria (endocyanosis) formed by a fungus is that of Geosiphon pyriformis with Nostoc punctiforme. The obligatory symbiotic fungus, G. pyriformis, belongs in the Glomeromycota, members of which form arbuscular mycorrhiza (AM) with the majority of vascular land plants and also with many ‘lower’ plants, thus driving most terrestrial ecosystems. There are many parallels between the Geosiphon–Nostoc and the AM symbioses. The fungal hyphae absorb soil nutrients and water, which they provide to the photoautotrophic partner. In turn, the plant supplies the biotrophic fungus with energy-rich soluble carbohydrates derived from photosynthesis. Here, the knowledge about the Geosiphon symbiosis is reviewed, as well as its role as a model symbiosis for the AM, a symbiosis inherently difficult to study. This is turned into relation to the probably >450 million years long-lasting co-evolution of AM fungi and land plants, and the functioning and ecology of the AM symbiosis.
The fungal symbionts of arbuscular mycorrhiza form a monophyletic group in the true Fungi, the phylum Glomeromycota. Fewer than 200 described species currently are included in this group. The only member of this clade known to form a different type of symbiosis is Geosiphon pyriformis, which associates with cyanobacteria. Because none of these fungi has been cultivated without their plant hosts or cyanobacterial partners, progress in obtaining multigene phylogenies has been slow and the nuclear-encoded ribosomal RNA genes have remained the only widely accessible molecular markers. rDNA phylogenies have revealed considerable poly-phyly of some glomeromycotan genera that has been used to reassess taxonomic concepts. Environmental studies using phylogenetic methods for molecular identification have recovered an amazing diversity of unknown phylotypes, suggesting considerable cryptic species diversity. Protein gene sequences that have become available recently have challenged the rDNA-supported sister group relationship of the Glomeromycota with Asco/Basidiomycota. However the number of taxa analyzed with these new markers is still too small to provide a comprehensive picture of intraphylum relationships. We use nuclear-encoded rDNA and rpb1 protein gene sequences to reassess the phylogeny of the Glomeromycota and discuss possible implications.
Une des solutions les plus prometteuses pour la restauration écologique des milieux dégradés, mais aussi pour l’agriculture, est l’utilisation des champignons mycorhiziens à arbuscules (CMA). En effet, ces champignons permettent de conférer aux plantes une meilleure nutrition minérale et une tolérance aux stress biotiques et abiotiques du milieu. L’étude réalisée ici part de l’hypothèse que les effets simultanés de plusieurs CMA taxonomiquement bien différents pourraient permettre de réduire la majorité des contraintes et permettre ainsi à la plante de s’adapter et se développer de façon optimale dans les sols extrêmes (ultramafiques) dégradés par l’activité minière. Les objectifs de cette thèse sont de caractériser les CMA isolés de ces milieux ultramafiques d’un point de vue taxonomique et fonctionnel (croissance et d’adaptation de la plante hôte). Ce travail a permis la découverte de cinq espèces nouvelles de CMA (Błaszkowski et al. 2017 ; Crossay et al. 2018). La complexité des méthodes d’identification de ces symbiotes, a suscité une réflexion scientifique qui a permis d’aboutir à la mise au point d’une méthode d’identification par MALDI-TOF MS précise et routinière pour l’identification des CMA (Crossay et al. 2017). Les différents isolats identifiés et cultivés en laboratoire ont ensuite été testés en conditions expérimentales afin d’évaluer leurs fonctions individuelles et collectives au sein des plantes hôtes (Crossay et al. 2019). En conclusion, la co-inoculation de ces différentes nouvelles espèces de CMA natives des sols ultramafiques de Nouvelle-Calédonie permet une grande amélioration de la croissance des plantes et de leur adaptation à ces milieux extrêmes.
Phosphorus is one of the most important limiting nutrients in Brazilian grasslands. Therefore, the function of soil microorganisms, especially arbuscular mycorrhizal fungi (AM fungi), has been attracted considerable attention, because AM fungi can absorb phosphorus from soil and supply it to host plants. To clarify their function in the Agropastoral system, the AM fungi in some fields in the Agropastoral system experiment in Brazil was investigated. The colonization of AM fungi was higher in soybean roots in the Continuous Crop field than in grass roots in Continuous Pasture and Degraded Pasture. Spore density was higher in the Continuous Crop field, where soybean was cultivated, than in the Pastures. Especially, Gigaspora sp. was abundantly found in the Continuous Crop field. These results suggest that even if the fields are close to each other, the dynamics of AM fungi is different probably due to different host plant species and fertilizer conditions.
Two ancestral clades of arbuscular mycorrhizal fungal species were discovered from deeply divergent ribosomal DNA sequences. They are classified here as two new families Archaeosporaceae and Paraglomaceae. Each family is phylogenetically distant from each other and from other glomalean families, despite similarities in mycorrhizal morphology and fatty acid profiles. Shared mycorrhizal morphology is not surprising, since it is highly conserved and resolves other taxa in Glomales at both family and suborder levels. At the present time, each family consists of one genus. Archaeospora (Archaeosporaceae) includes three species forming atypical Acaulospora-like spores from sporiferous saccules. Two of these species are dimorphic, forming Glomus-like spores as well. Paraglomus (Paraglomaceae) consists of two species forming spores indistinguishable from those of Glomus species. Morphological characters once considered unique, such as the sporiferous saccule defining species of Acaulosporaceae, clearly are distributed in phylogenetically distant groups. The simple design of spores of some species in Glomus also masks considerable divergence at the molecular level. It is the combination of DNA sequences, fatty acid profiles, immunological reactions against specific monoclonal antibodies, and mycorrhizal morphology which provides the basis for recognizing Archaeospora and Paraglomus. These results reinforce the value of molecular data sets in providing a clearer understanding of phylogenetic relationships, which in turn can lead to a more robust taxonomy.
The most common benefit host plants receive form arbusular mcycorrhizal fungi is enhanced phosphorus nutrition. Important aspects of this process: P metabolism in the fungus, cytological and enzymological factors involved in transport, and what is known about the mechanism and location of transfer to host cells are summarized Finally a model is proposed which synthesizes these data to describe the flow of P from soil, though the AM fungus, to the root cortical cell.
ThefirstDNAsequencesobtainedfromarbuscularendomycorrhizalfungiarereported.Theywere obtained bydirectlysequencingoverlappingamplifiedfragmentsofthenucleargenes codingforthesmallsubunit rRNA.Thesesequences were usedtodevelopa polymerasechainreactionprimer(VANSI)thatenablesthe specificamplificationofa portionofthevesicular-arbuscularendomycorrhizalfungussmallsubunitrRNA directlyfroma mixtureofplantandfungaltissues.Thespecificityofthisprimerforarbuscularendomycor- rhizalfungiwas demonstratedbytestingiton a numberoforganismsandbysequencingthefragmentamplified from colonized leek (Allium porum) roots. This approach, coupled with other molecular techniques, will facilitate rapid detection, identification, and possibly quantitation of arbuscular endomycorrhizal fungi.
To analyze the phylogeny and molecular evolution of the entomophthoralean fungi, we determined the small subunit nuclear ribosomal RNA gene sequences for four representative species of the En- tomophthorales and the trichomycete Smittium culi- setae (Harpellales) in the Zygomycota. Ten published reference sequences were added to this analysis. The phylogeny, inferred from the aligned 1480 positions and using the choanoflagellate Diaphanoeca grandis (Choanoflagellida) as an outgroup, divided seven zygomycete species into four clusters. The four species in the Entomophthorales were placed in two clusters, i.e., Basidiobolus ranarum in one cluster containing Chy- tridium, Spizellomyces and Neocallimastix, and the remaining three species Conidiobolus coronatus, Entomo- phthora muscae, and Zoophthora radicans in another cluster containing Mucor. Glomus etunicatum is basal to ascomycetes and basidiomycetes, and Smittium culi- setae was placed close to the divergence of Entomophthorales from the chytrid-GZojrews-ascomycete-basid- iomycete clade. Our analysis also suggests loss of flagella on several lineages in the tree and great phylogenetic divergence among the chytrids.
To analyze the phylogeny and molecular evolution of the entomophthoralean fungi, we determined the small subunit nuclear ribosomal RNA gene sequences for four representative species of the Entomophthorales and the trichomycete Smittium culisetae (Harpellales) in the Zygomycota. Ten published reference sequences were added to this analysis. The phylogeny, inferred from the aligned 1480 positions and using the choanoflagellate Diaphanoeca grandis (Choanoflagellida) as an outgroup, divided seven zygomycete species into four clusters. The four species in the Entomophthorales were placed in two clusters, i.e., Basidiobolus ranarum in one cluster containing Chytridium, Spizellomyces and Neocallimastix, and the remaining three species Conidiobolus coronatus, Entomophthora muscae, and Zoophthora radicans in another cluster containing Mucor. Glomus etunicatum is basal to ascomycetes and basidiomycetes, and Smittium culisetae was placed close to the divergence of Entomophthorales from the chytrid-Glomus-ascomycete-basidiomycete clade. Our analysis also suggests loss of flagella on several lineages in the tree and great phylogenetic divergence among the chytrids.
summaryLittle information currently exists on species diversity in communities of arbuscular mycorrhizal fungi (AMF), mainly owing to difficulties in identification of field extracted spores on the basis of morphology. The possibility was explored to identify individual AMF spores from the field on the basis of a molecular marker, namely the nuclear ribosomal DNA encoding the highly conserved 5.8S rRNA with the two flanking internal transcribed spacers (ITS region), known to vary between species. A technique involving polymerase chain reaction followed by restriction fragment length polymorphism analysis (PCR–RFLP) was developed to amplify and characterize the ITS region from single AMF spores. PCR reactions with extracts from single spores of three AMF species, raised under glasshouse conditions, yielded reproducibly a single amplification product of the ITS region in sufficient amounts to allow cleavage with several restriction enzymes. The size of the ITS region, c. 600 base pairs, varied only slightly between species. Digestion of the PCR products with the restriction enzymes Hinfl and Taq I resulted in banding patterns that were reproducible for different individual spores of a given species, but showed clear differences between the three species tested. The sum of the fragment sizes was sometimes greater than the size of the original PCR product, e.g. in Glomus mosseae. Clones of the amplification product from a single spore of this fungus were obtained and sequenced. This yielded two closely related but different sequences, indicating that two different ITS regions co-existed in the spore. The RLFP pattern of the amplification product of the spore was a result of an amalgamation of these two sequences. The technique was applied to AMF spores collected from a species-rich grassland. Spores were sorted into morphological groups on the basis of their colour, size, and shape, and then subjected to PCR–RFLP analysis. In some morphological groups, a large percentage of spores failed to yield an amplification product, probably because they had lost their contents. A group of Glomus spores yielding amplification products in the majority of cases was further investigated: PCR RFLP analysis on 10 individual spores from the field produced 10 different patterns. Similar results were obtained with other groups of spores. The results suggest that the diversity in natural AMF communities and the genetic diversity within individual spores might he much greater than previously thought.
The internal transcribed spacer (ITS) region of the nuclear ribosomal RNA was amplified, cloned and sequenced from spores of five isolates of the arbuscular mycorrhizal fungus Glomus mosseae and one isolate each of G. fasciculatum, G. dimorphicum and G. coronatum. The sequences comprised ITSI (113–121 base pairs), 5.8S rRNA gene (154 base pairs) and ITS2 (222–230 base pairs). The ITS sequences were at least 84% identical, but only distantly related to other published sequences. Their identification as Glomus sequences was confirmed by sequencing part of the adjoining SSU rRNA gene from one isolate; it was 98% identical to the published G. mosseae sequence. Two to four clones were sequenced from each isolate, and in many instances these were substantially different (up to 6 % divergence) even when they were obtained from a single spore. Sequences from a single isolate were generally, but not always, more similar to each other than to those from different isolates. In addition to base substitutions, many ITS sequences differed slightly in length because of the insertion or deletion of up to three nucleotides within short runs of a single base, generally A or T. These changes were found at 22 separate sites within the ITS, and were more common between than within isolates. Phylogenetic relationships deduced from length variation and from base substitution were similar. The variation among isolates from different continents (Europe, Asia, South America) was no greater than among those from a smaller geographic range. The ITS1 and 2 sequences from G. caronatum were clearly distinct from the other isolates (11–16% divergence), but those of G. fasciculatum and G. dimorphicum fell within the range of variation exhibited by G. mosseae.
A new species of endogonaceous fungus, Acaulospora nicolsonii, is described from Great Britain. Attempts to obtain the species in pure pot culture have failed, though it sporulated in a pot containing Zea mays and mycorrhizal Glomus species. Wound healing of the type previously thought to be confined to Gigaspora spp. was noted on a hypha attached to a sporiferous saccule of A. nicolsonii.