scholarly journals The ftsZ Gene of the Endocellular Bacterium ‘Candidatus Glomeribacter gigasporarum’ Is Preferentially Expressed During the Symbiotic Phases of Its Host Mycorrhizal Fungus

2009 ◽  
Vol 22 (3) ◽  
pp. 302-310 ◽  
Author(s):  
Iulia-Andra Anca ◽  
Erica Lumini ◽  
Stefano Ghignone ◽  
Alessandra Salvioli ◽  
Valeria Bianciotto ◽  
...  
Keyword(s):  
Positive Impact ◽  
Marker Gene ◽  
Mycorrhizal Fungus ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Bacterial Gene ◽  
Gene Transcripts ◽  
Polymerase Chain ◽  
Fungal Life Cycle ◽  
Polymerase Chain Reaction Data

The arbuscular mycorrhizal fungus (AM) Gigaspora margarita consistently hosts bacteria, named ‘Candidatus Glomeribacter gigasporarum,’ inside its cytoplasm. Endobacteria have a positive impact on fungal fitness during the presymbiotic phase, prior to plant roots colonization. We tested the hypothesis that the endobacterium and its cell divisions depend on fungal metabolism, mirroring also the events of the fungal life cycle which are influenced by plant signals. We first cloned a fragment of ftsZ, a marker gene for bacterial division, and then analyzed its expression along the different stages of fungus development. The bacterial gene transcripts showed the highest values when the fungus was associated to the plant, and peaked in the extraradical mycelium. Strigolactones, which are known to stimulate the AM fungal growth, caused a significant transcript increase in the germinated spores in the absence of the plant. The quantitative real-time reverse-transcription polymerase chain reaction data were strengthened by the quantification of the dividing bacteria, which were increasing in number in germinating spores after the strigolactone treatment. The bioactive molecule alone did not cause any change in the number of bacteria after their isolation from the fungus, thus showing that the strigolactone alone cannot confer free-living capacities to the bacterium.

scholarly journals Towards Growth of Arbuscular Mycorrhizal Fungi Independent of a Plant Host

2002 ◽  
Vol 68 (4) ◽  
pp. 1919-1924 ◽  
Author(s):  
Ulrich Hildebrandt ◽  
Katharina Janetta ◽  
Hermann Bothe
Keyword(s):  
Mycorrhizal Fungi ◽  
Glomus Intraradices ◽  
Mycorrhizal Fungus ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Plant Host ◽  
Significant Step ◽  
Hyphal Coils ◽  
K 12 ◽  
Root Tissues

ABSTRACT When surface-sterilized spores of the arbuscular mycorrhizal fungus (AMF) Glomus intraradices Sy167 were germinated on agar plates in the slightly modified minimum mineral medium described by G. Bécard and J. A. Fortin (New Phytol. 108:211-218, 1988), slime-forming bacteria, identified as Paenibacillus validus, frequently grew up. These bacteria were able to support growth of the fungus on the agar plates. In the presence of P. validus, hyphae branched profusely and formed coiled structures. These were much more densely packed than the so-called arbuscule-like structures which are formed by AMF grown in coculture with carrot roots transformed with T-DNA from Agrobacterium rhizogenes. The presence of P. validus alone also enabled G. intraradices to form new spores, mainly at the densely packed hyphal coils. The new spores were not as abundant as and were smaller than those formed by AMF in the monoxenic culture with carrot root tissues, but they also contained lipid droplets and a large number of nuclei. In these experiments P. validus could not be replaced by bacteria such as Escherichia coli K-12 or Azospirillum brasilense Sp7. Although no conditions under which the daughter spores regerminate and colonize plants have been found yet, and no factor(s) from P. validus which stimulates fungal growth has been identified, the present findings might be a significant step forward toward growth of AMF independent of any plant host.

scholarly journals Asymbiotic mass production of the arbuscular mycorrhizal fungus Rhizophagus clarus

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Sachiko Tanaka ◽  
Kayo Hashimoto ◽  
Yuuki Kobayashi ◽  
Koji Yano ◽  
Taro Maeda ◽  
...  
Keyword(s):  
Life Cycle ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Terrestrial Ecosystems ◽  
Hormonal Control ◽  
Root Colonisation ◽  
Rhizophagus Clarus ◽  
Am Symbiosis ◽  
Fungal Life Cycle

AbstractArbuscular mycorrhizal (AM) symbiosis is a mutually beneficial interaction between fungi and land plants and promotes global phosphate cycling in terrestrial ecosystems. AM fungi are recognised as obligate symbionts that require root colonisation to complete a life cycle involving the production of propagules, asexual spores. Recently, it has been shown that Rhizophagus irregularis can produce infection-competent secondary spores asymbiotically by adding a fatty acid, palmitoleic acid. Furthermore, asymbiotic growth can be supported using myristate as a carbon and energy source for their asymbiotic growth to increase fungal biomass. However, the spore production and the ability of these spores to colonise host roots were still limited compared to the co-culture of the fungus with plant roots. Here we show that a combination of two plant hormones, strigolactone and jasmonate, induces the production of a large number of infection-competent spores in asymbiotic cultures of Rhizophagus clarus HR1 in the presence of myristate and organic nitrogen. Inoculation of asymbiotically-generated spores promoted the growth of host plants, as observed for spores produced by symbiotic culture system. Our findings provide a foundation for the elucidation of hormonal control of the fungal life cycle and the development of inoculum production schemes.

Adhesion to hyphal matrix and antifungal activity ofPseudomonasstrains isolated fromTuber borchiiascocarps

2000 ◽  
Vol 46 (3) ◽  
pp. 259-268 ◽  
Author(s):  
C Sbrana ◽  
G Bagnoli ◽  
S Bedini ◽  
C Filippi ◽  
M Giovannetti ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Mycorrhizal Fungus ◽  
Physiological Role ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Ectomycorrhizal Fungus ◽  
Growth Modulation ◽  
Tuber Borchii ◽  
Pseudomonas Spp ◽  
Fungal Contaminants

Pseudomonas spp. isolates from Tuber borchii ascocarps, known to be able to produce phytoregulatory and biocontrol substances in pure culture, were used to perform studies on their possible physiological role in nature. Antimycotic activity was confirmed against fungal contaminants isolated from the ascocarps, suggesting that populations associated with Tuber borchii fruit bodies may play a role in the maintenance of ascocarp health. Fifty-five percent of strains tested were also able to release metabolites which affected T. borchii mycelial growth and morphogenesis in culture. On the contrary, growth of the arbuscular mycorrhizal fungus Glomus mosseae and the ectomycorrhizal fungus Laccaria bicolor, putative competitors of Tuber for mycorrhizal infection sites on roots, was not influenced by the presence of any bacterial strain. The possibility that these bacteria, which show antifungal activity and fungal growth modulation activities, might be incorporated in the developing ascocarp by means of their preferential adhesion to Tuber mycelium is discussed.Key words: Tuber borchii, associated bacteria, Pseudomonas spp., biocontrol, adhesion.

scholarly journals Asymbiotic mass production of the arbuscular mycorrhizal fungus Rhizophagus clarus

2020 ◽  
Author(s):  
Sachiko Tanaka ◽  
Kayo Hashimoto ◽  
Yuuki Kobayashi ◽  
Koji Yano ◽  
Taro Maeda ◽  
...  
Keyword(s):  
Life Cycle ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Terrestrial Ecosystems ◽  
Hormonal Control ◽  
Root Colonisation ◽  
Rhizophagus Clarus ◽  
Am Symbiosis ◽  
Fungal Life Cycle

AbstractArbuscular mycorrhizal (AM) symbiosis is a mutually beneficial interaction between fungi and land plants and promotes global phosphate cycling in terrestrial ecosystems. AM fungi are recognised as obligate symbionts that require root colonisation to complete a life cycle involving the production of propagules, asexual spores. Recently it has been shown that Rhizophagus irregularis can produce infection-competent secondary spores asymbiotically by adding a fatty acid, palmitoleic acid. Further, asymbiotic growth can be supported using myristate as a carbon and energy source for their asymbiotic growth to increase fungal biomass. However, spore production and the ability of these spores to colonise host roots were still limited compared to co-culture of the fungus with plant roots. Here we show that a combination of two plant hormones, strigolactone and methyl jasmonate, induces production of a large number of infection-competent spores in asymbiotic cultures of Rhizophagus clarus HR1 in the presence of myristate and organic nitrogen. Inoculation of asymbiotically-generated spores promoted the growth of Welsh onions, as observed for spores produced by symbiotic culture system. Our findings provide a foundation for elucidation of hormonal control of the fungal life cycle and development of new inoculum production schemes.

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