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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 ?
Singer R, Araujo I (1979) Litter decomposition and ectomycorrhiza in Amazonian forest.
4 Ectomycorrhiza and Nitrogen Provision to the Host Tree
On morphoanatomical basis, mycorrhizas are categorised into three different groups, namely ectomycorrhiza, endomycorrhiza and ectendomycorrhiza.
In temperate forests, ectomycorrhiza (ECM) serve as a major organ for controlling nutrient uptake by trees, and it was estimated that up to 95% of the short roots in these trees contain ECM (Smith and Read 1997).
It is not known if the species of the cerrado form ectomycorrhiza.
Accumulation and localization of aluminium in root tips of loblolly pine seedlings and the associated ectomycorrhiza Pisolithus tinctorius.
Ectomycorrhiza is a mutualistic symbiotic relationship between the roots of higher plants and fungi.
Table 1 Physiological Responses of Emergent Seedlings of Picea engelmannii to Colonization of Root Surfaces by the Alpine-White Complex of Ectomycorrhiza Fungi Photosynthesis Conductance ([micro]mol Conductance C[O.
First, different fungal species/strains vary in their ability to form ectomycorrhiza or to enhance plant nutrient uptake when grown in association with different plant species and under different environmental conditions (e.
This is the first detailed report on molecular identification of aboveground fruiting body as well as its ectomycorrhiza, Lactarius species, associated with wide host range.
Ontogeny of Alnus rubra-Alpova diplophloeus ectomycorrhiza.