Introduction
mycorrhizae are called the organs formed by the root of a plant and the mycelium of a fungus. Its function is to absorb, so that spread along the ground to provide water and nutrients and protecting the roots of some diseases.
In return, the fungus gets the sugar it needs, from plant photosynthesis. So, thanks to the performance of mycorrhizae, growth is enhanced and improved endurance. Most plants perform this symbiosis with fungi, for which it is necessary that the environmental conditions are favorable to both.
Importance of Mycorrhizae for Ecosystem
Mycorrhizae play a key role in the terrestrial ecosystem, playing a number of functions essential to the health of many plants and crops. And is that the role of the fungus is biotrophic colonize the bark of a particular result, without causing any harm, but rather integrates becoming part of it. In turn, the fungus also colonizes the soil around the root using the external mycelium, so that helps the host to acquire mineral nutrients and water.
For its part, the plant provides the fungus with carbon compounds that come from photosynthesis. For this reason, develop mycorrhizae a key role in the development and maintenance of many ecosystems, so that can be found in all soils and all land climates. Because of the role played mycorrhizae as protectors of crops can reduce fertilizer and herbal medicine in those plants that possess them.
Mycorrhizal Fungi mutualistic association that occurs between the fungus and root is used by the majority of vascular plants and fungi-like basidiomycetes, ascomycetes and zygomycetes. Much of edible mushrooms in the forest of pine, as the nízcalo, the brats, the death cap mushroom, the bold, pomfret or cat's tongue, are fruiting bodies of these fungi. Arbuscular Mycorrhizae
most common mycorrhizal fungi are arbuscular, which provide major economic benefits due to its beneficial effect on growth and stress tolerance of a large crop. Here are some micro earthquakes that are characterized by their inability to reproduce except by the colonization of plant roots, which is called the host.
fungi that lead to this type of mycorrhizae are microscopic Zygomycetes Glomales order. Forming arbuscular mycorrhizae are most herbaceous and some woody legumes, cereals, fruit, the vast majority of horticultural crops and many shrubs, dwarf shrubs and herbs of forest ecosystems. Degraded Soil Benefit
Another major role of mycorrhizae is assisting in the establishment and protection of those plants that are less productive soils, as affected by desertification, pollution by heavy metals or salinity. Thus, it provides many benefits to crops and yields healthy food. Thus, arbuscular mycorrhizae can stop soil erosion and desertification, especially in Mediterranean ecosystems.
On the other hand, in soils affected by the negative effects of heavy metals have shown that mycorrhizal plants have greater resistance, with the ability to get to immobilize the metals in the roots, preventing them from passing to the shoot of the plant. Finally, with regard to salinity should be noted that currently are conducting studies that indicate that these fungi are more appropriate for this factor.
Mycorrhizae: "Fungus-root",
Mycorrhizae are organs formed by the root of a plant and the mycelium of a fungus. Function as an absorption system which extends along the ground and is able to provide water and nutrients (nitrogen and phosphorus in particular) to the plant roots and protect against some diseases. The fungus in turn receive plant sugars from photosynthesis. There are thousands of species of fungi that form mycorrhizal symbiosis with trees. Most families of higher plants mycorrhizal Earth.
What are mycorrhizae? The term mycorrhiza
globally describes a series of structures formed by the partnerships established between various kinds of soil fungi and the roots of most vascular plants (Frank, 1885), and has even been described on non-vascular plants .
As a widespread phenomenon, the term "mycorrhiza" has become at the user level in the name designating the fungi involved in their formation, although this name is not very correct, these same routines have been coined colloquial terms such as "mycorrhizal 'fungi make contact mycorrhizal plants and 'mycorrhization' to indicate the establishment of symbiosis.
How They Work?
type in these mutualistic symbiosis, the fungus supplies the plant inorganic compounds (minerals) it needs for nutrition (mycotrophy) and the plant provides the fungus heterotrophic organic compounds (photosynthates).
The establishment of these associations involves creating strong interdependencies, so much so that the fungus becomes a part of the root system, so perfectly integrated into the same looks very difficult or even impossible to develop without the assistance of its host plant, and it may have Range dependence of the fungus, ranging from absolute to relative to a greater or lesser degree (Barea et al., 1993).
How many types of mycorrhizae exist?
generally allowed five types of mycorrhizae (Harley and Smith, 1983), namely:
Ectomycorrhizae: The fungi that form, Basidiomycetes and Ascomycetes, develop a thick layer of mycelium on the cortical area feeder roots of the plant. Occur mainly on forest and woody species.
Endomycorrhizae: The fungi that produce them are characterized by intracellularly colonize the root cortex. Within this group there are three distinct types:
Orquideomicorrizas (associated with Orquidiáceas).
Ericomicorrizas (linked to the family Ericaceae, with many structural similarities with
ectendomicorrizas.
arbuscular mycorrhizae: Characterized by forming intracellular arbuscules and certainly the most widespread and economic and ecological importance.
Ectendomicorrizas:
fungi that produce dual colonize the roots: externally forming a cortical mantle and internally penetrating intracellularly in the cortex.
On what plants are established?
mycorrhizal associations occurring on almost all vascular plants with a few exceptions such as the families Cruciferae, Chenopodiaceae, Cyperaceae, Caryophyllaceae and Juncaceae (Azcón Aguilar and Barea, 1997) and also set in Bryophytes and Pteridophytes, although there is little information on these symbiosis with vascular plants (Moser and Haselwandter, 1983).
Among the vascular plants colonized by 'mycorrhiza' are all woody species of forestry interest (Fagaceae, Betulaceae, Pinaceae, etc.), all species of horticultural interest (Solanaceae, grass, etc..) and many families of ornamental importance (Orquidiáceas, Rosaceae ...). This gives a clear idea of \u200b\u200bthe ecological and economic importance of mycorrhizae.
What are the Major Categories of mycorrhizal fungi?
• In ectomycorrhizae: Suillus, Cortinarius, Rhizopogon, Cenococcuym, Thelefora, Pisolithus. • In orquideomicorrizas
: Armillariella, Gymnopilus, Marasmius, Fomes, Xerotus, Ceratobasidium, Corticium, Sebacina, Tulasnella. • In ericomicorrizas
: Pezizella.
• In arbuscular mycorrhizae: Acaulospora, Entrophospora, Gigaspora, Glomus, and Scutellospora Sclerocystis. • In ectendomicorrizas
: Endogone. How to Produce
Colonization?
At first there is a mutual identification plant fungus in the rhizosphere, in regions close to the feeder roots, this recognition seems mediated by substances exuded by the root cause of the mycelium growth and a positive biotropism it towards the root. Then there is the intercellular contact to form a structure called appressorium Thirdly, morphological and structural changes in tissues colonized by the fungus, and the organization of the cell wall of the symbiont fungi. Is subsequently physiological integration of both symbionts, and finally there is an alteration of enzymatic activities that are coordinated between the symbionts to integrate metabolic processes (
Specificity in the Formation of Mycorrhizae? While
mycorrhizal associations are generally considered non-specific, meaning that any symbiotic fungus can colonize any plant receptive, however there are "preferences" or better compatibility between certain pairs affinity fungus / plant. In contrast there are also cases such as Eucalyptus, Malus, Arbutus (Meyer, 1973) that the total associative specificity makes these and other species are colonized at the same time as different as ectomycorrhiza formation and endomycorrhizas.
What are the Effects of mycorrhizal associations?
Mycorrhizae act at several levels, causing morphological and anatomical changes in the host plants such as changes in root stem ratio in root tissue structure, the number of chloroplasts, increased lignification, disruption of hormonal balances. .., effects that are not only explicable as a mere improvement of plant nutrition due to increased efficiency of nutrient uptake by the root through to the formation of mycorrhizae, but responds to metabolic changes deeper and more complex due to physiological integration of symbionts.
Another most interesting effects of mycorrhizae is their role in the ecosystem in which they develop, and interact with various microorganisms mycorrhizosphere establishment for profitable cooperation with each other and generally competing with pathogenic type, and even interacting with rhizosphere microfauna (nematodes, aphids, mites, ...), but its apparent protective role is relative (and Haselwandter Moser, 1983).
What are the Practical Applications of Mycorrhizae?
Apart from their scientific, studies of plant physiological type, microbiology, biotechnology applications in commercial production and ornamental horticulture, is to highlight its application to processes of reforestation revegetation (Salamanca et al., 1992) and recovery in arid and degraded soils (Daft et al., 1975).
Another cutting-edge applications is easy to deduce from all this, its application in biological control against pathogens in the rhizosphere.
But the best reason to work with and the satisfaction they offer to their handlers is to get vigorous and healthy plants.
Conclusion
In Nature this symbiosis occurs spontaneously. It is estimated that between 90 and 95% of higher plants have mycorrhizae as usual.
is possible that one fungus forms mycorrhizae with more than one plant at a time, thus establishing a connection between different plants, and this facilitates the existence of parasitic plants (some of whom do not even carry out photosynthesis, such as the genus Monotropa), which extracted all they need mycobiont fungus and other plants with which it also establishes symbiosis. In addition, several fungi (in Sometimes different species) may mycorrhizal same plant at the same time.
www.encuentros.uma.es/encuentros55/micorrizas Bibliographies References.
www.plantasyhogar.com / garden
Carlos López Encina is Scientific Collaborator (CSIC) in the Experimental Station Mayora. Muñoz Araceli Barceló
Researcher
es.wikipedia.org CIFA / wiki / Mycorrhiza
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