Mycorrhizas: Integrated Development between Roots and Fungi

Peterson, R. L.; Farquhar, M. L.

doi:10.2307/3760561

Cited by 50 publications

(21 citation statements)

References 34 publications

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“…The establishment of a symbiosis between soilborne fungi is indispensable for germination under natural conditions. The symbiotic association between orchids and fungi is relatively unique in the plant kingdom in that the symbiotic fungi of orchid plants seem to acquire no benefits (Peterson and Farquhar 1994, Smith and Read 1997). The association is parasitism rather than mutualistic symbiosis and has received much attention from both evolutionary and symbiotic points of view.…”

Section: Introductionmentioning

confidence: 99%

Enhanced symbiotic seed germination of Cypripedium macranthos var. rebunense following inoculation after cold treatment

Shimura

Koda

2005

Physiologia Plantarum

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Cypripedium macranthos var. rebunense is a well‐known wild orchid in Japan, and is considered to be a symbol for rare plant conservation. A fungus isolated from roots of C. macranthos var. rebunense induced symbiotic germination of the species in vitro. Cold treatment of the seeds at 4°C prior to fungal inoculation was required for the symbiotic germination. Changing the timing of inoculation of the fungus to the seeds greatly improved germination frequency. Maximum germination was attained after seeds were inoculated just after the cold treatment for 12 weeks, and approximately 20% of the seeds developed into protocorms more than 1 mm long. These results suggest that fungal inoculation takes place at the beginning of spring in nature, and the tough impervious seed coat may preserve the seed from the infection during autumn and winter seasons. The lengthy culture period of more than 16 weeks at 20°C on the same medium with the fungus caused gradual browning and rot of the protocorms. By elimination of the fungus with a fungicide and by transfer to a nutrient rich medium, approximately 20% of the protocorms developed into healthy plantlets. The methods obtained here appear to be applicable to symbiotic germination of many other threatened Cypripedium spp.

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Section: Introductionmentioning

confidence: 99%

Enhanced symbiotic seed germination of Cypripedium macranthos var. rebunense following inoculation after cold treatment

Shimura

Koda

2005

Physiologia Plantarum

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“…formation of ectomycorrhiza) and non‐symbiosis‐related processes (i.e., fruiting body formation). Both the ectomycorrhizal mantle sheath and the fruiting body tissues are composed of pseudoparenchyma, a pseudotissue made of aggregated hyphae that looks like the plant parenchyma (Brunner and Scheidegger, ; Peterson and Farquhar, ). ECM developed by MiSSP8‐ RNAi lines display a disorganized fungal mantle and no Hartig net formation.…”

Section: Discussionmentioning

confidence: 99%

Laccaria bicolor MiSSP8 is a small‐secreted protein decisive for the establishment of the ectomycorrhizal symbiosis

Pellegrin

Daguerre

Ruytinx

et al. 2019

Environmental Microbiology

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Summary The ectomycorrhizal symbiosis is a predominant tree–microbe interaction in forest ecosystems sustaining tree growth and health. Its establishment and functioning implies a long‐term and intimate relationship between the soil‐borne fungi and the roots of trees. Mycorrhiza‐induced Small‐Secreted Proteins (MiSSPs) are hypothesized as keystone symbiotic proteins, required to set up the symbiosis by modifying the host metabolism and/or building the symbiotic interfaces. L. bicolor MiSSP8 is the third most highly induced MiSSPs in symbiotic tissues and it is also expressed in fruiting bodies. The MiSSP8‐RNAi knockdown mutants are strongly impaired in their mycorrhization ability with Populus, with the lack of fungal mantle and Hartig net development due to the lack of hyphal aggregation. MiSSP8 C‐terminus displays a repetitive motif containing a kexin cleavage site, recognized by KEX2 in vitro. This suggests MiSSP8 protein might be cleaved into small peptides. Moreover, the MiSSP8 repetitive motif is found in other proteins predicted secreted by both saprotrophic and ectomycorrhizal fungi. Thus, our data indicate that MiSSP8 is a small‐secreted protein involved at early stages of ectomycorrhizal symbiosis, likely by regulating hyphal aggregation and pseudoparenchyma formation.

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“…They suggested that G. carbonaria was moderately pathogenic, but supposed that the formation of a rudimentary Hartig net indicated that the fungus may be capable of forming mutualistic mycorrhizal symbiosis under some conditions (Egger & Paden 1986b). Under artificial conditions, ectomycorrhizal fungi may sometimes turn pathogenic, penetrating the cell walls and causing chlorotic reactions of the host tissue (Peterson & Farquhar 1994), indicating that there is a fine balance between being a mutualistic mycorrhizal symbiont and an intracellular pathogen. The inter‐ and intracellular infections by G. carbonaria of epidermal and cortical root cells of lodgepole pine in vitro observed by Egger & Paden (1986b), may be related to the ectendomycorrhizal infection of pine observed in Wilcoxina species.…”

Section: Discussionmentioning

confidence: 99%

“…Contrastingly, spruce, fir, hemlock and Douglas fir became universally ectomycorrhizal, i.e. with intercellular penetration only, with the same mycobionts, suggesting that the nature of symbiosis and mycorrhizal morphology is largely determined by the phytobiont (Peterson & Farquhar 1994). Thus, the biotrophic relationship between G. carbonaria and Norway spruce may well be ‘pure’ ectomycorrhizal in nature, while associations with pines may be ectendomycorrhizal.…”

Section: Discussionmentioning

confidence: 99%

The postfire discomycete Geopyxis carbonaria (Ascomycota) is a biotrophic root associate with Norway spruce (Picea abies) in nature

1998

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The hypothesis that the postfire discomycete Geopyxis carbonaria (Ascomycota, Pezizales, Pyronemataceae) has a biotrophic association with roots of Norway spruce (Picea abies) in nature was tested by isolation of fungal strains from fresh, brown, smooth mycorrhiza-like root tips of Norway spruce collected from below the depth of detrimental heat penetration in a postfire site. The morphology of seven culture isolates originating from the smooth mycorrhiza-like root tips of two different spruce trees was congruent with the morphology of axenic culture isolates obtained from ascospores of G. carbonaria. DNA sequences of the nuclear ribosomal internal transcribed spacers ITS1 and ITS2 from these root-derived cultures and the ascosporic G. carbonaria culture isolates were found to be identical, further supporting the conclusion that the isolates were conspecific. The extensive ascocarp and ascospore formation of G. carbonaria which succeeds a forest fire may be explained in terms of a fungal escape from a moribund tree associate. Possible ecological adaptations of G. carbonaria to the pre- and postfire community are discussed.

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Mycorrhizas: Integrated Development between Roots and Fungi

Cited by 50 publications

References 34 publications

Enhanced symbiotic seed germination of Cypripedium macranthos var. rebunense following inoculation after cold treatment

Enhanced symbiotic seed germination of Cypripedium macranthos var. rebunense following inoculation after cold treatment

Laccaria bicolor MiSSP8 is a small‐secreted protein decisive for the establishment of the ectomycorrhizal symbiosis

The postfire discomycete Geopyxis carbonaria (Ascomycota) is a biotrophic root associate with Norway spruce (Picea abies) in nature

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