The micorriza word, of Greek origin, defines Symbiosis between fungus (mycos) and the roots (rhizos) of one Planta . Like in all symbiotic relation, the participants obtain benefit. In this case the plant mainly receives from the fungus mineral nutrients and water, and the fungus obtains from the plant carbohydrates and Vitamins that it by itself is incapable to synthesize whereas she it can make thanks to Photosynthesis and other internal reactions.

Many plants present/display micorrizas to increase to the water absorption and mineral salts of the ground. The micorrizas are the association between roots of a plant and the mycelium of a fungus, so that all the extension of the mycelium participates in the absorption of nutrients for the plant.

In the Nature this symbiosis takes place spontaneously. Esteem that enters the 90 and 95% of the plants superiors present/display micorrizas of habitual form.

It is possible that a same fungus forms the micorriza with more than a plant simultaneously, settling down in this way a connection enters different plants; this facilitates the existence of parasitic plants (some of which not even realize the photosynthesis, like those of sort Monotroops ), that extract everything what micobionte needs the fungus and the other plants with which this one also establishes symbiosis. Also, several fungi (sometimes of different species) can micorrizar a same plant at the same time.

Advantages of the micorrización

The advantages provided by micorrización : for the plants they are numerous. Thanks to her, the plant is able to explore more volume of ground del that reaches with its roots, when adding him in this work Hifas of the fungus; also it catches with greater facility certain elements ( phosphorus, Nitrogen, Calcium and Potassium ) and water of the ground. The protection offered by the fungus causes that, in addition, the plant is more resistant to the changes of temperature and the acidification of the ground derived from the presence of Sulfur, Magnesium and Aluminum . In case all this outside little, some physiological reactions of the fungus induce to the root to stay activates during more time than if she were not micorrizada.

All this results in a greater longevity of the plant: in fact, it has been verified that some trees, as pines are incapable to live more than two years when they are without micorrizar. In other species, this union is so narrow that without her the plant cannot subsist, as is the case of Orchids the plants whose Seeds lack endosperma (nutritional substances of reserve) depend completely on the fungus to feed themselves and to germinate later.

The infection by the root by the fungus takes place from propágulos presents in the ground. They also can be esporas and pieces of hifas of the fungus and roots already micorrizadas. With the purpose of to ensure the forest success of the company, seedtime of the majority of plants foods or decoration and repopulations that are carried out at present accompanies the new plants and buds with fragments by the fungus more adapted to establish micorrícicas associations with each species that goes away to cultivar.soya enbolatada

Types of micorrizas

The majority of the terrestrial plants presents/displays micorrizas, and most probable it is than the rest descend from micorrizadas plants that are lost secondly this characteristic. In the case of the fungi, most of the 5000 identified Species in the micorrizas belongs to the division Basidiomycota, whereas in more exceptional cases members of are observed Ascomycota . The third division that has been observed forming micorrizas is Glomeromycota, a group that, in fact, only knows itself in micorrizógena association and whose members die when it is deprived to them of the presence by roots.

According to their morphology, the micorrizas are divided in different groups between which it is possible to emphasize two main ones: ectomicorrizas and endomicorrizas .

  • the ectomicorrizas are characterized because hifas of the fungus by the root does not penetrate inside Cells, if not that are located on and between the separations of these. They are possible to be observed at first and they present/display the call Network of Hartig . This type of micorrización is the one that predominates between the trees of temperate zones, being especially characteristic in pines, There are Robles and Níscalos the fungi is as much Basidiomycota like Ascomycota .

  • In the endomicorrizas, however, is no external mantle that can be seen at first. Hifas is introduced initially between the cells by the root, but soon they penetrate inside these, forming arbúsculos nutritional vesicles and . For this reason, or is known also like micorrizas micorrizas VAM vesículoarbusculares . The fungi belong to the division Glomeromycota and they occur in all type of plants, although with predominance of grass and Pulses Abundan in poor grounds like those with the prairies and Steppes the high mountain and tropical Forests . In Atlantic Forest appears next to the ectomicorrizas.

Besides these two great groups, the following smaller types are distinguished:

  • Ectendomicorrizas: they present/display external mantle, like the ectomicorrizas, but also they penetrate inside the cells, like the endomicorrizas. Arbúsculos vesicles do not exist nor. is observed so much in Basidiomycota as Ascomycota and is more abundant in Angiospermaes that in Gimnospermas .

  • Orquidoides or micorrizas of ball of yarn: Micorrizas of essential Orchids for its development and youthful life. In adult state, the plant can get to become independent from the fungus in some cases.

  • Ericoides: simpler and simple type. It penetrates in the cells to form balls of yarn.

  • Arbutoides: external mantle and penetration in the cells, where rollers form .

  • Monotropoides: the form of penetration in the cells is something different.

Discovery

First in observing the micorrizas and baptizing them with the name that take at the moment he was botanical German Albert Berhhard Frank, in 1885, after detecting his presence in several fruit trees. In 1900, French Bernard discovered its extreme importance in the life and development of the orchids. In 1910 began to extend its study in the plants used in Agriculture and Gardening .

However, 1955 were not until, with the publication of the first studies of Mosse in England, when the micorrizas stopped considering themselves as exceptions and accepted their real importance and majority. In more recent times, numerous Fossil findings have allowed to determine that the origin and is present at of the micorrizas are enormously old, because they have been gotten to find Esporas of Glomeromycota in layers of up to 460 million years of antiquity, pertaining to the period Ordovícico . The forms arbusculares already are enough extended at the time of appearance of the first terrestrial plants in the fossil registry, makes 400 million years. These plants, like the species major Rhynia, lacked authentic roots, presenting/displaying solely an underground stem or Rizoma del that several aerial stems excelled. The absorption of nutrients, therefore fell almost exclusively on the micorrícico fungus, reason why which can be said that the presence of these was essential for the extension of the vegetal life to mainland, after would arrive later Animal

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