mycorrhiza

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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 ?
Mycorhizal plants uptake Zn over more distances crossing the depletion zone.
The effects of whey on the colonization and sporulation of arbuscular mycorhizal fungus (AMF), Glomus intraradices, in lentil (Lens orientalis) plants.
Improved procedures for clearing roots and staining parasitic and vasicular-arbuscular mycorhizal fungi for rapid assessment of infection.
Arbuscular mycorhizal fungi infection in desert riparian forest and its environmental implications: A case study in the lower reach of Tarim River.
Unfortunately, any hypothesis based on this premise would be faulty on two counts: (1) it would not be falsifiable sensu Popper (1972), and (2) the Vaccinium corymbosum root system (as in all ericads) is strictly mycorhizal (Vander Kloet, 1988), thus part of the "wood-wide-web" where resources are shared among taxa related or not (Simard et al., 1997).
In view of the well established role of AMF in nutrient uptake for host plants in different forms and from different sources, plant-wide mycorhizal web is likely to influence competitive interactions of invasive and native plant species through differential exchange of nutrients between them.