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Arthur Schusler - One of the best experts on this subject based on the ideXlab platform.

  • Geosiphon pyriforme a fungus forming endocytobiosis with nostoc cyanobacteria is an ancestral member of the glomales evidence by ssu rrna analysis
    Journal of Molecular Evolution, 1996
    Co-Authors: H Gehrig, Arthur Schusler, Manfred Kluge
    Abstract:

    Geosiphon pyriforme inhabiting the surface of humid soils represents the only known example of endocytobiosis between a fungus (Zygomycotina; macrosymbiont) and cyanobacteria (Nostoc; endosymbiont). In order to elucidate the taxonomical and evolutionary relationship ofGeosiphon pyriforme to fungi forming arbuscular mycorrhiza (AM fungi), the small-subunit (SSU) ribosomal RNA genes ofGeosiphon pyriforme andGlomus versiforme (Glomales; a typical AM fungus) were analyzed and aligned with SSU rRNA sequences of several Basidiomycetes, Ascomycetes, Chytridiomycetes, and Zygomycetes, together with all AM-fungal (Glomales) sequences published yet.

  • Geosiphon pyriforme an endosymbiotic association of fungus and cyanobacteria the spore structure resembles that of arbuscular mycorrhizal am fungi
    Botanica Acta, 1994
    Co-Authors: Arthur Schusler, D Mollenhauer, E Schnepf, Manfred Kluge
    Abstract:

    The zygomycete Geosiphon pyriforme is the only known endocyanosis of a fungus. The Nostoc spp. filaments are included in photosynthetically active and nitrogen fixing, multinucleated bladders, which grow on the soil surface. The spores of the fungus are white or slightly brownish. They are about 250 μm in diameter and develop singly on hyphal ends or, less frequently, intercalarly. The wall of the spores consists of a thin innermost layer, a laminated inner layer with a thickness of about 10–13 μm, and an evanescent outer layer. The laminated layer is composed of helicoidally arranged microfibrils, and is separated from the evanescent outer layer by a thin electron-dense sublayer. Polarisation microscopy indicates the occurrence of chitin. Shape and wall ultrastructure of the Geosiphon spores and their cytoplasm resemble that of Glomus spores, but are different from that of other genera of the Glomales and Endogonales. Germination occurs by a single thick hyphal outgrowth directly through the spore wall. Like various AM forming fungi, Geosiphon pyriforme contains endocytic bacteria-like organisms, which are not surrounded by a host membrane. Our observations indicate that Geosiphon is a potential AM fungus.

Manfred Kluge - One of the best experts on this subject based on the ideXlab platform.

  • Geosiphon pyriforme a fungus forming endocytobiosis with nostoc cyanobacteria is an ancestral member of the glomales evidence by ssu rrna analysis
    Journal of Molecular Evolution, 1996
    Co-Authors: H Gehrig, Arthur Schusler, Manfred Kluge
    Abstract:

    Geosiphon pyriforme inhabiting the surface of humid soils represents the only known example of endocytobiosis between a fungus (Zygomycotina; macrosymbiont) and cyanobacteria (Nostoc; endosymbiont). In order to elucidate the taxonomical and evolutionary relationship ofGeosiphon pyriforme to fungi forming arbuscular mycorrhiza (AM fungi), the small-subunit (SSU) ribosomal RNA genes ofGeosiphon pyriforme andGlomus versiforme (Glomales; a typical AM fungus) were analyzed and aligned with SSU rRNA sequences of several Basidiomycetes, Ascomycetes, Chytridiomycetes, and Zygomycetes, together with all AM-fungal (Glomales) sequences published yet.

  • Geosiphon pyriforme an endosymbiotic association of fungus and cyanobacteria the spore structure resembles that of arbuscular mycorrhizal am fungi
    Botanica Acta, 1994
    Co-Authors: Arthur Schusler, D Mollenhauer, E Schnepf, Manfred Kluge
    Abstract:

    The zygomycete Geosiphon pyriforme is the only known endocyanosis of a fungus. The Nostoc spp. filaments are included in photosynthetically active and nitrogen fixing, multinucleated bladders, which grow on the soil surface. The spores of the fungus are white or slightly brownish. They are about 250 μm in diameter and develop singly on hyphal ends or, less frequently, intercalarly. The wall of the spores consists of a thin innermost layer, a laminated inner layer with a thickness of about 10–13 μm, and an evanescent outer layer. The laminated layer is composed of helicoidally arranged microfibrils, and is separated from the evanescent outer layer by a thin electron-dense sublayer. Polarisation microscopy indicates the occurrence of chitin. Shape and wall ultrastructure of the Geosiphon spores and their cytoplasm resemble that of Glomus spores, but are different from that of other genera of the Glomales and Endogonales. Germination occurs by a single thick hyphal outgrowth directly through the spore wall. Like various AM forming fungi, Geosiphon pyriforme contains endocytic bacteria-like organisms, which are not surrounded by a host membrane. Our observations indicate that Geosiphon is a potential AM fungus.

Thomas D Bruns - One of the best experts on this subject based on the ideXlab platform.

  • ancestral lineages of arbuscular mycorrhizal fungi glomales
    Molecular Phylogenetics and Evolution, 2000
    Co-Authors: Dirk Redecker, Joseph B Morton, Thomas D Bruns
    Abstract:

    Abstract Using new and existing 18S rRNA sequence data, we show that at least five species of glomalean fungi lie outside the previously defined families and diverged very early in the evolution of that group. These five fungi would have been missed by many previous ecological studies because their sequences are not well matched to available taxon-specific primers and they do not stain well with the standard reagents used for morphological analysis. Based upon spore morphology, these species are currently assigned to Glomus and Acaulospora, and two of the species are dimorphic, exhibiting spore stages of both genera. This suggests that dimorphic spores are the ancestral state for the order and that one or the other morphology was lost in various lineages. Our analyses also show that Geosiphon pyriforme, a symbiont with cyanobacteria, is not necessarily a sister group of the Glomales; instead, it may be derived from mycorrhizal ancestors.

Christopher Walker - One of the best experts on this subject based on the ideXlab platform.

  • a new fungal phylum the glomeromycota phylogeny and evolution
    Fungal Biology, 2001
    Co-Authors: Arthur Schuβler, Daniel Schwarzott, Christopher Walker
    Abstract:

    The ecologically and economically important arbuscular mycorrhizal (AM) fungi, crucial in the ecology and physiology of land plants, and the endocytobiotic fungus, Geosiphon pyriformis, are phylogenetically analysed by their small subunit (SSU) rRNA gene sequences. They can, from molecular, morphological and ecological characteristics, unequivocally be separated from all other major fungal groups in a monophyletic clade. Consequently they are removed from the polyphyletic Zygomycota, and placed into a new monophyletic phylum, the Glomeromycota. The recognition of this monophyletic group, which probably diverged from the same common ancestor as the Ascomycota and Basidiomycota, gives these fungi their proper status, and provides a basis for a new and natural systematics of these fascinating, yet largely hidden organisms, with three new orders (Archaeosporales, Paraglomerales, Diversisporales) described herein. Additionally, several clades resolve at family level; their formal description is in progress.

  • Glomus, the Largest Genus of the Arbuscular Mycorrhizal Fungi (Glomales), Is Nonmonophyletic
    Molecular Phylogenetics and Evolution, 2001
    Co-Authors: Daniel Schwarzott, Christopher Walker, Arthur Schüßler
    Abstract:

    Arbuscular mycorrhizal (AM) fungi form a widespread and ecologically important symbiosis with plants in the land ecosystem. The phylogeny of the largest presently accepted genus, Glomus, of the monogeneric family Glomaceae (Glomales; AM fungi) was analyzed. Phylogenetic trees were computed from nearly full-length SSU rRNA gene sequences of 30 isolates, and show that “Glomus” is not monophyletic. Even after the very recent separation of Archaeospora and Paraglomus from “Glomus,” the genus further separates into two suprageneric clades. One of them diverges further into two subclades, differing by phylogenetic distances equivalent to family level. The other, comprising Glomus versiforme, G. spurcum, and a species morphologically similar to G. etunicatum, is not closely related to the Glomaceae, but clusters together with the Acaulosporaceae and Gigasporaceae in a monophyletic clade. Based on the molecular evidence, a new family, separate from the Glomaceae, is required to accommodate this group of organisms, initially named Diversisporaceae fam. ined. The current taxonomic concept of the recently erected family Archaeosporaceae also requires future emendation, because Geosiphon pyriformis (Geosiphonaceae) renders Archaeospora, the sole genus formally included in this family, paraphyletic. The suborders Gigasporineae and Glominaeae are not congruent with the natural phylogeny of the AM fungi. Our data necessitate a general reexamination of the generic concepts within the Glomales. In addition to the new family structure hypothesized herein, establishment of at least three new genera will be necessary in the future.

Daniel Schwarzott - One of the best experts on this subject based on the ideXlab platform.

  • a new fungal phylum the glomeromycota phylogeny and evolution
    Fungal Biology, 2001
    Co-Authors: Arthur Schuβler, Daniel Schwarzott, Christopher Walker
    Abstract:

    The ecologically and economically important arbuscular mycorrhizal (AM) fungi, crucial in the ecology and physiology of land plants, and the endocytobiotic fungus, Geosiphon pyriformis, are phylogenetically analysed by their small subunit (SSU) rRNA gene sequences. They can, from molecular, morphological and ecological characteristics, unequivocally be separated from all other major fungal groups in a monophyletic clade. Consequently they are removed from the polyphyletic Zygomycota, and placed into a new monophyletic phylum, the Glomeromycota. The recognition of this monophyletic group, which probably diverged from the same common ancestor as the Ascomycota and Basidiomycota, gives these fungi their proper status, and provides a basis for a new and natural systematics of these fascinating, yet largely hidden organisms, with three new orders (Archaeosporales, Paraglomerales, Diversisporales) described herein. Additionally, several clades resolve at family level; their formal description is in progress.

  • Glomus, the Largest Genus of the Arbuscular Mycorrhizal Fungi (Glomales), Is Nonmonophyletic
    Molecular Phylogenetics and Evolution, 2001
    Co-Authors: Daniel Schwarzott, Christopher Walker, Arthur Schüßler
    Abstract:

    Arbuscular mycorrhizal (AM) fungi form a widespread and ecologically important symbiosis with plants in the land ecosystem. The phylogeny of the largest presently accepted genus, Glomus, of the monogeneric family Glomaceae (Glomales; AM fungi) was analyzed. Phylogenetic trees were computed from nearly full-length SSU rRNA gene sequences of 30 isolates, and show that “Glomus” is not monophyletic. Even after the very recent separation of Archaeospora and Paraglomus from “Glomus,” the genus further separates into two suprageneric clades. One of them diverges further into two subclades, differing by phylogenetic distances equivalent to family level. The other, comprising Glomus versiforme, G. spurcum, and a species morphologically similar to G. etunicatum, is not closely related to the Glomaceae, but clusters together with the Acaulosporaceae and Gigasporaceae in a monophyletic clade. Based on the molecular evidence, a new family, separate from the Glomaceae, is required to accommodate this group of organisms, initially named Diversisporaceae fam. ined. The current taxonomic concept of the recently erected family Archaeosporaceae also requires future emendation, because Geosiphon pyriformis (Geosiphonaceae) renders Archaeospora, the sole genus formally included in this family, paraphyletic. The suborders Gigasporineae and Glominaeae are not congruent with the natural phylogeny of the AM fungi. Our data necessitate a general reexamination of the generic concepts within the Glomales. In addition to the new family structure hypothesized herein, establishment of at least three new genera will be necessary in the future.