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n. pl. mycorrhi·zae (-zē) or mycorrhi·zas
The symbiotic association of the mycelium of a fungus with the roots of a plant, as is found in the majority of vascular plants.

my′cor·rhi′zal adj.


(Greek myco- fungus, rhiza root) an association between a FUNGUS and the roots of a higher plant. In some cases the fungus breaks down PROTEINS or AMINO ACIDS that are soluble and can be absorbed by the higher plant. In most cases, only nitrogen and phosphorus compounds result from fungal activity. Carbohydrates synthesized by the higher plants are absorbed by the fungus, so the relationship is a form of SYMBIOSIS. Some plants which lack chlorophyll, such as the bird's nest orchid, rely on mycorrhizas for carbohydrates in addition to protein.

There are two types of mycorrhiza: ectomycorrhiza and endomycorrhiza. In an ectomycorrhiza the infecting fungus occurs on the surface of the root and possibly between the cells of the root cortex, but does not penetrate such cells. The root becomes covered by a sheath of fungal tissue and looks different from an uninfected root. It is thicker, has no root hairs or root cap and may be a different colour. Ectomycorrhizae are found mainly on trees, such as oak and pine. In an endomycorrhiza the fungus develops within the cells of the root cortex. Subsequently the root cells digest the fungus leaving only knots of fungal material in the cells. There is usually little difference in the morphology of the root and a sheath of fungal tissue is not normally formed.

References in periodicals archive ?
Intra-specific and intra-sporocarp ITS variation of ectomycorrhizal fungi as assessed by rDNA sequencing of sporocarps and pooled ectomycorrhizal roots from a Quercus woodland.
Caption: FIGURE 1: Toots volume of Eucalyptus granais produced in a Quartzarenic Neosols, or non-inoculated with different isolates of ectomycorrhizal fungi alone or in mixture, at 60 and 90 days after planting in the greenhouse.
Genetic study on indole-3-acetic acid production by ectomycorrhizal Hebeloma species: inter- and intraspecific variability in homo- and dikaryotic mycelia.
Utilization of rocks and ectomycorrhizal fungi to promote growth of eucalypt.
Fungus tendrils provides almost 70% to 100% phosphate directly to the plant though both ectomycorrhizal and endomycorrhizal association, huge mineral boost which may ultimately reduce the need for farmers to saturate crop fields with phosphate fertilizer.
Diagne N, Thioulouse J, Sanguin H, Prin Y, Krasova-Wade T, Sylla S, Galiana A, Baudoin E, Neyra M, SvistoonoffS, Lebrun M, Duponnois R (2013) Ectomycorrhizal diversity enhances growth and nitrogen fixation of Acacia mangium seedlings.
Genetic variability phosphate solubilizing activity of the ectomycorrhizal fungus Laccaria bicolor (Maire) P.
2016, Testing the importance of a common ectomycorrhizal network for dipterocarp seedling growth and survival in tropical forests of Borneo.
Patterns of ectomycorrhizal host specificity and potential among Pacific Northwest conifers and fungi.
At our study site in the Mealy Mountains, the necessary ectomycorrhizal fungal communities (Reithmeier and Kernaghan, 2013), soil nutrients (Jacobs et al.
This grazing system has been found to improve soil quality in mixed-grass prairie by stimulating ectomycorrhizal fungal activity (Manske and Caesar-TonThat, 2003).
However, small whorled pogonia's dependency on a subterranean, ectomycorrhizal fungus is believed to be a limiting factor--without the fungus and the trees that support it, the species cannot survive.