Introduction to mycorrhizas
Mycorrhizal symbiosis refers to the association of fungi with plant roots. This relationship is predominantly mutualistic, that is, with both partners benefiting from the association. There are seven types of mycorrhizal association, but common to all types is the net movement of carbon, generally (but not always) from the plant host to the fungus partner. In return, a fungus may confer increased nutrient supply, defence against pathogenic attack, and drought resistance to its partner plant. Click here for more information on the effects of mycorrhizas.
The term 'mycorrhiza' was first used by Professor A. B. Frank in the 1880's. Frank was the first person to describe the symbiotic relationship between trees and fungi, which he named 'mykorhiza'. The word comes from the Greek mykes and rhiza, the combination meaning fungus-root.
More than 90% of all plant families studied (80% of species) in both agricultural and natural environments form mycorrhizal associations and they can be essential for plant nutrition. Mycorrhizas are found in a wide range of habitats, including deserts, lowland tropical rainforests, high latitudes and altitudes, and aquatic ecosystems. There are few exceptions to the rule that mycorrhizas are found in all plant species that are economically important to man. Click here to learn about the commercial applications of mycorrhizas.
Mycorrhizal associations are widespread amongst plant families and appear to have evolved and spread with the early land plants (effectively enabling early plants with small ineffective roots to invade and become established in the terrestrial environment). Click here to find out more about the evolution of mycorrhizas.
Most of the non-mycorrhizal plant families have highly specialised nutritional strategies; including carnivorous plants (e.g. Droseraceae, Lentibulariaceae, Nepenthaceae, Sarraceniaceae), parasites, often lacking roots (Apodanthaceae, Balanophoraceae, parasitic Convolvulariaceae, Orobanchaceae, Santalaceae) or plants with cluster roots, which are dense aggregations of lateral roots with long root hairs (many Proteaceae members, especially those occurring in highly infertile soils of Western Australia and South Africa; non-mycorrhizal cluster roots also occur in the Myricaceae and some genera of the Fabaceae (e.g. Lupinus). For a complete list of non-mycorrhizal plant families visit Mark Brundrett's Mycorrhizal Associations website.
Further information about mycorrhizas can be found in the new textbook 21st Century Guidebook to Fungi by David Moore, Geoffrey D. Robson & Anthony P.J. Trinci. Published 2011 by Cambridge University Press: ISBN: 9780521186957. URL: ttp://www.cambridge.org/gb/knowledge/isbn/item6026594/?site_locale=en_GB. View Amazon page.
Updated December 15, 2016