It has been proposed that habitat type and the distinct functions of different mycorrhizas help determine which type of symbiosis is predominant in a given area. Pinaceae is the oldest extant plant family in which symbiosis with EcM fungi occurs, and fossils from this family date back to 156 million years ago. ĮcM plants and fungi exhibit a wide taxonomic distribution across all continents (apart from Antarctica), suggesting that the EcM symbiosis has ancient evolutionary roots. There is paleobiological and molecular evidence that arbuscular mycorrhizas (AM) originated at least 460 million years ago. Mycorrhizal symbioses are ubiquitous in terrestrial ecosystems, and it is possible that these associations helped to facilitate land colonization by plants. Well known EcM fungal fruiting bodies include the economically important and edible truffle ( Tuber) and the deadly death caps and destroying angels ( Amanita). In exchange, the fungal symbiont is provided with access to carbohydrates.Īlthough samples of ectomycorrhizas are usually taken from the surface horizon due to of higher root density, ectomycorrhizas are known to occur in deep tree roots (a depth more than 2 meters), some occurring at least as deep as 4 meters. The hyphal network helps the plant to take up nutrients including water and minerals, often helping the host plant to survive adverse conditions. This sheathing mantle can be up to 40 µm thick, with hyphae extending up to several centimeters into the surrounding soil. Instead they form an entirely intercellular interface known as the Hartig net, consisting of highly branched hyphae forming a latticework between epidermal and cortical root cells.Įctomycorrhizas are further differentiated from other mycorrhizas by the formation of a dense hyphal sheath, known as the mantle, surrounding the root surface. Unlike other mycorrhizal relationships, such as arbuscular mycorrhiza and ericoid mycorrhiza, ectomycorrhizal fungi do not penetrate their host's cell walls. Research on ectomycorrhizas is increasingly important in areas such as ecosystem management and restoration, forestry and agriculture. Ectomycorrhizas form on the roots of around 2% of plant species, usually woody plants, including species from the birch, dipterocarp, myrtle, beech, willow, pine and rose families. The mycobiont is often from the phyla Basidiomycota and Ascomycota, and more rarely from the Zygomycota. ectomycorrhizas or ectomycorrhizae, abbreviated EcM) is a form of symbiotic relationship that occurs between a fungal symbiont, or mycobiont, and the roots of various plant species. Ectomycorrhizal symbiosis, showing root tips with fungal mycelium from the genus AmanitaĪn ectomycorrhiza (from Greek ἐκτός ektos, "outside", μύκης mykes, "fungus", and ῥίζα rhiza, "root" pl.
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