Cultural Characteristics of Ectomycorrhizal Fungi

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Mycorrhizae Fungal Symbioses with Roots Ectomycorrhizae Cultural Characteristics of Ectomycorrhizal Fungi Absorption of Nutrients Techniques of Ectomycorrhizal Inoculation Resistance to Plant Diseases by Ectomycorrhiza

Cultural Characteristics of Ectomycorrhizal Fungi

Cultural Characteristics of Ectomycorrhizal Fungi
The ectomycorrhizal fungi can easily be isolated in the vegetative form although the identification of such fungi becomes difficult since reproductive bodies are not readily formed in culture media. Fruiting bodies can, however, be seen on the soil surface near the trees, from which fungal cultures can easily be isolated. These fungi grow slowly in culture and require special nutrients such as thiamine, simple amino acids and other undefined constituents (collectively known as the M-factor) of root exudates. Melin and his associates in sweden have shown that the M-factor is exuded by roots of plants susceptible to mycorrhizal infection and not by plants resistant to it. Experiments with Boletus variegatus have shown that low doses of M-factor are stimulatory to growth of the fungus whereas high doses become inhibitory.

The inhibitory portions of M-factor appear to be excessive in old secondarily thickened axils or roots while the stimulatory portions appear to be so in the primary rootlets. Ectomycorrhizal fungi are generally not cellulolytic or lignolytic and therefore have to depend on carbohydrates from their host plants. Experiments with 14C labelled sucrose, glucose, fructose and 14CO₂ have shown that most of the carbon requirements of the fungus come from the host plant by way of root excretions. Metabolites produced by the fungus influence the structure and morphology of the root system. These substances include auxins such as indole acetic acid and other unknown growth substances. They are partly responsible for the dichotomy of pine rootlets. In this way, the fungus and the host plant mutually control the morphological and physiological activities of the symbiotic system. The carbon nutrition of the fungus is dependent on the photosynthetic activity of the host which is balanced by the greater efficiency of absorption and storage of nutrients afforded by the fungal partner

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Endomycorrhizae of Orchids Arbuscular Mycorrhiza Isolation of AM Fungal Spores Methods of AM Fungal Inoculation Legume Arbuscular Mycorrhiza Interaction

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