mycorrhiza

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Related to Endomycorrhizae: Ectomycorrhizal

mycorrhiza

or

mycorhiza

(mī′kə-rī′zə)
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.

mycorrhiza

(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 ?
Notice that arbuscular mycorrhizae are referred to as "endomycorrhizae" in this Web site.
Graham JH, Hodge NC, Morton JB (1995) Fatty acid methyl ester profiles for characterisation of Glomalean fungi and their endomycorrhizae. Applied and Environmental Microbiology 61, 58-64.
Conceptual approaches for the rational use of VA endomycorrhizae in agriculture: possibilities and limitations.
There are two broad categories of mycorrhizae: ectomycorrhizae and endomycorrhizae.
Most plants, including common crops, host mycorrhizae that grow inside root cells These fungi are called endomycorrhizae. While there are several varieties of endomycorrhizae, crop plants most commonly host VAM, or vesicular-arbuscular mycorrhizae.
Pfeffer and co-workers study the most common type of mycorrhizae, which are called endomycorrhizae because the fungi live inside--rather than between--root cells.
This effect, first recognized by modern agronomists in the early 1950s (Pelissier, 1953; Sowers and Issoufou, 1992), has been variously attributed to improved soil physical and chemical properties (Depommier et al., 1992; Geiger et al., 1992), reduced soil and air temperatures (Dancette and Poulain, 1968; Vandenbeldt and Williams, 1992), symbiosis with rhizobium and arbuscular endomycorrhizae (Ducousso, 1990), previous termite activity (Brouwer et al., 1992), and improved nutrient recycling (Charreau and Vidal, 1965).