BACTERIUM‐LIKE ORGANELLES IN THE VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGUS <i>GLOMUS CALEDONIUS</i>

Macdonald, R. M.; Chandler, Muriel R.

doi:10.1111/j.1469-8137.1981.tb07486.x

Cited by 67 publications

(37 citation statements)

References 6 publications

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“…They seem to belong to the Gram-positive bacteria. Their ultrastructure is similar to the BLOs described in other members of the Glomales and Endogonales, like Glomus mosseae (Macdonald et al, 1982;Meier and Charvat, 1992), Gigaspora heterogama, an unidentified "white reticulate" AM fungus (Macdonald et al, 1982), Glomus caledonium (Macdonald and Chandler, 1981), Acaulospora laevis (Mosse, 1970b), Gigaspora margarita (Macdonald et al, 1982;Sward, 1981a, b, c), another unidentified AM fungus (Protzenko, 1974(Protzenko, , 1975, Endogone flammicorona (Bonfante-Fasolo and Scannerini, 1977b), Glomus versiforme (Garriock et al, 1989), a member of the Glomus fasciculatus complex (BonfanteFasolo and Scannerini, 1977a;Scannerini and BonfanteFasolo, 1982), and in undetermined members of the Glomales, forming an AM-like association with hepatophytes (Ligrone and Lopes, 1989), anthocerophytes (Ligrone, 1988) and a Lycopodium species (Schmid and Oberwinkler, 1993) (for a review of BLOs in AM fungi see Scannerini and Bonfante-Fasolo, 1992).…”

Section: Discussionmentioning

confidence: 71%

Geosiphon pyriforme, an Endosymbiotic Association of Fungus and Cyanobacteria: the Spore Structure Resembles that of Arbuscular Mycorrhizal (AM) Fungi

et al. 1994

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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.

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Section: Discussionmentioning

confidence: 71%

Geosiphon pyriforme, an Endosymbiotic Association of Fungus and Cyanobacteria: the Spore Structure Resembles that of Arbuscular Mycorrhizal (AM) Fungi

et al. 1994

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“…Nevertheless, some bacteria have been found in the cytoplasm of AMF spores (4,18). The role of AMF sporeassociated bacteria is not clear.…”

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confidence: 99%

Bacteria Associated with Spores of the Arbuscular Mycorrhizal Fungi Glomus geosporum and Glomus constrictum

Roesti

Ineichen

Braissant

et al. 2005

Appl Environ Microbiol

125

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Spores of the arbuscular mycorrhizal fungi (AMF) Glomus geosporum and Glomus constrictum were harvested from single-spore-derived pot cultures with either Plantago lanceolata or Hieracium pilosella as host plants. PCR-denaturing gradient gel electrophoresis analysis revealed that the bacterial communities associated with the spores depended more on AMF than host plant identity. The composition of the bacterial populations linked to the spores could be predominantly influenced by a specific spore wall composition or AMF exudate rather than by specific root exudates. The majority of the bacterial sequences that were common to both G. geosporum and G. constrictum spores were affiliated with taxonomic groups known to degrade biopolymers (Cellvibrio, Chondromyces, Flexibacter, Lysobacter, and Pseudomonas). Scanning electron microscopy of G. geosporum spores revealed that these bacteria are possibly feeding on the outer hyaline spore layer. The process of maturation and eventual germination of AMF spores might then benefit from the activity of the surface microorganisms degrading the outer hyaline wall layer.

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“…In addition to interacting with environmental and ectosymbiotic bacteria, some plant-associated fungi harbor bacteria within their hyphae (first noted as "bacteria-like organisms" of unknown function) (38). These bacteria, best known from living hyphae of several species of the Glomeromycota and Mucoromycotina, can alter fungal interactions with host plants in diverse ways (see references 12, 31, and 51).…”

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confidence: 99%

Diverse Bacteria Inhabit Living Hyphae of Phylogenetically Diverse Fungal Endophytes

Hoffman

Arnold

2010

Appl Environ Microbiol

230

224

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Both the establishment and outcomes of plant-fungus symbioses can be influenced by abiotic factors, the interplay of fungal and plant genotypes, and additional microbes associated with fungal mycelia. Recently bacterial endosymbionts were documented in soilborne Glomeromycota and Mucoromycotina and in at least one species each of mycorrhizal Basidiomycota and Ascomycota. Here we show for the first time that phylogenetically diverse endohyphal bacteria occur in living hyphae of diverse foliar endophytes, including representatives of four classes of Ascomycota. We examined 414 isolates of endophytic fungi, isolated from photosynthetic tissues of six species of cupressaceous trees in five biogeographic provinces, for endohyphal bacteria using microscopy and molecular techniques. Viable bacteria were observed within living hyphae of endophytic Pezizomycetes, Dothideomycetes, Eurotiomycetes, and Sordariomycetes from all tree species and biotic regions surveyed. A focus on 29 fungus/bacterium associations revealed that bacterial and fungal phylogenies were incongruent with each other and with taxonomic relationships of host plants. Overall, eight families and 15 distinct genotypes of endohyphal bacteria were recovered; most were members of the Proteobacteria, but a small number of Bacillaceae also were found, including one that appears to occur as an endophyte of plants. Frequent loss of bacteria following subculturing suggests a facultative association. Our study recovered distinct lineages of endohyphal bacteria relative to previous studies, is the first to document their occurrence in foliar endophytes representing four of the most species-rich classes of fungi, and highlights for the first time their diversity and phylogenetic relationships with regard both to the endophytes they inhabit and the plants in which these endophyte-bacterium symbiota occur.Traits related to the establishment and outcome of plantfungus symbioses can reflect not only abiotic conditions and the unique interactions of particular fungal and plant genotypes (49,50,56,59,62,67) but also additional microbes that interact intimately with fungal mycelia (4, 12, 42). For example, mycorrhizosphere-associated actinomycetes release volatile compounds that influence spore germination in the arbuscular mycorrhizal (AM) fungus Gigaspora margarita (Glomeromycota) (14). Levy et al. (34) describe Burkholderia spp. that colonize spores and hyphae of the AM fungus Gigaspora decipiens and are associated with decreased spore germination. Diverse "helper" bacteria have been implicated in promoting hyphal growth and the establishment of ectomycorrhizal symbioses (23,26,57,70). Minerdi et al. (43) found that a consortium of ectosymbiotic bacteria limited the ability of the pathogen Fusarium oxysporum to infect and cause vascular wilts in lettuce, with virulence restored to the pathogen when ectosymbionts were removed.In addition to interacting with environmental and ectosymbiotic bacteria, some plant-associated fungi harbor bacteria within their hyphae (first ...

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BACTERIUM‐LIKE ORGANELLES IN THE VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGUS GLOMUS CALEDONIUS

Cited by 67 publications

References 6 publications

Geosiphon pyriforme, an Endosymbiotic Association of Fungus and Cyanobacteria: the Spore Structure Resembles that of Arbuscular Mycorrhizal (AM) Fungi

Geosiphon pyriforme, an Endosymbiotic Association of Fungus and Cyanobacteria: the Spore Structure Resembles that of Arbuscular Mycorrhizal (AM) Fungi

Bacteria Associated with Spores of the Arbuscular Mycorrhizal Fungi Glomus geosporum and Glomus constrictum

Diverse Bacteria Inhabit Living Hyphae of Phylogenetically Diverse Fungal Endophytes

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