What fungi form mycorrhiza with woody plants. What is mycorrhiza in biology? Mycorrhizal fungi, or symbiotrophs

Mycorrhiza is a symbiosis of vascular plant roots with certain fungi. Many tree species do not develop well without mycorrhiza. Mycorrhiza is known in most groups of vascular plants. Only a few flowering families do not form it, such as cruciferous and sedge. Many plants can develop normally without mycorrhiza, but with a good supply of mineral elements, especially phosphorus.

Mycorrhiza in appearance and structure is different. In tree species, mycorrhiza develops more often, forming a dense sheath of thin threads around the root. Such mycorrhiza is called exotrophic (from the Greek "exo" - external and "trophe" - food), as it settles on the surface of the organisms that feed it. Mycorrhiza, the hyphae of which are inside the cells of the plants that feed it, is called endotrophic - internal. There are also transitional forms of mycorrhiza.

Several dozen species of fungi are involved in the formation of mycorrhiza, mainly from the class of basidiomycetes. In some plants, ascomycetes, phycomycetes and imperfect fungi take part in the formation of mycorrhiza.

Edible mushrooms are widely known: in the birch forest - boletus, in aspen - boletus. The main mycorrhiza-forming organisms are camelina, white fungus, butterdish, fly agaric and others. They can occur on one tree species, and on many.

The symbiosis of the roots of higher plants with fungi has developed historically, on peat and humus soils, nitrogen on these soils can be available to plants thanks to fungi.

It is believed that fungi supply plants with mineral nutrients, especially on soils with hard-to-reach forms of phosphorus, potassium, and participate in nitrogen metabolism.

In relation to mycorrhiza, woody plants are divided into: mycotrophic (pine, larch, spruce, fir, oak, etc.), weakly mycotrophic (birch, maple, linden, elm, bird cherry, etc.), non-mycotrophic (ash, legumes, etc.).

Mycotrophic plants suffer in the absence of mycorrhizal fungi in the soil, their growth and development are severely inhibited. Weakly mycotrophic can grow in the absence of mycorrhiza, but with it they develop more successfully.

Mycorrhiza is of great importance in the life of forest species. The presence of mycorrhiza and its deep study as a phenomenon of cohabitation with plants was first discovered and carried out by Kamensky (1881). He studied the interaction of mycorrhiza under spruce, beech and some other conifers.

Mycorrhiza is characteristic of the entire group of conifers, as well as oak, beech, birch, etc. It has been established that without mycorrhiza it is impossible normal development most woody plants. It contributes to a better supply of moisture and nutrients to the plant.

Mycorrhiza is formed by various types of fungi, mainly cap mushrooms, which are widely distributed in our forests. On the roots of forest species, fungal plexuses (mycelia) are formed annually, which in the spring are introduced into the tissues and cells of the sucking extremities of the roots, wrapping them in mushroom caps. By autumn, the mycorrhiza dies off.

Mycorrhiza performs the function of roots. It supplies forest species with water, and, consequently, with nutrients dissolved in water, causes a stronger branching of the root system, contributing to this increase in the active surface of the roots in contact with the soil, destroys the humus substances of the soil and turns them into compounds available to trees. It is believed that mycorrhiza protects trees from toxic substances in the soil.

Cohabitation of roots with fungi causes faster growth of trees. Back in 1902, G. N. Vysotsky found that in the steppe regions, oak and pine seedlings take root better and grow well if mycorrhiza is present on their roots.

Numerous domestic studies, especially recently, have shown that the normal growth of most tree species - oak, hornbeam, conifers is impossible without mycorrhiza. Euonymus, acacia, fruit trees and some other species develop normally without mycorrhiza. They can grow without mycorrhiza, but nevertheless it is formed by linden, birch, elm, most of the shrubs.

Mycorrhiza has acquired great importance in connection with field-protective afforestation, especially in the steppe, where the soil does not contain mycorrhiza.

For the success of steppe afforestation, the most important event is the infection of sown areas with mycorrhiza.

The fungus also, as a result of symbiosis with the root system of a woody plant, apparently uses some nitrogen-free substances present in the root system of a woody plant.

Plants with mycorrhiza on their roots are mycotrophic plants, plants without mycorrhiza are autotrophic. Mycorrhiza has not been found in leguminous plants, but special nodules with nitrogen-fixing bacteria are formed on their roots. Ash, privet, euonymus, skumpia, apricot, mulberry and other woody plants do not form mycorrhiza, even if they grow in forest conditions.

Many forest species (elm and other elms, maple, linden, alder, aspen, birch, mountain ash, apple and pear, willow, poplar, etc.) form mycorrhiza in forest conditions. Under conditions unfavorable for the development of mycorrhiza, they grow without mycorrhiza.

It is obvious that the knowledge of these factors is necessary for the arborist when carrying out silvicultural work, and especially on non-forest areas, where it is necessary to add mycorrhizal soil when growing mycotrophic plants in a nursery or directly in planting or sown areas.

Currently, about 300 thousand plant species grow on our land, of which 90% (according to other sources, even more) live in close cooperation with mushrooms, and these are not only trees and shrubs, but also herbs.

This relationship between plants and fungi scientific world received the name mycorrhiza (i.e. mushroom root; from the Greek. mykes- mushroom, rhiza- root). Currently, only a small part of plants (and these are individual species from the family of amaranth, haze, cruciferous) can do without mycorrhiza, while most of them interact with fungi to one degree or another.

Some plants cannot do without mushrooms at all. For example, in the absence of symbiont fungi, orchid seeds do not germinate. Orchids throughout their lives are fed by mycorrhiza, although they have a photosynthetic apparatus and can independently synthesize organic substances.

The first who drew attention to the need for fungi for plants were foresters. After all, a good forest is always rich in mushrooms. The connection of mushrooms with certain trees is indicated by their names - boletus, boletus, etc. In practice, foresters encountered this only during artificial afforestation. At the beginning of the 20th century, attempts were made to plant forests on the steppe lands, especially for planting valuable species - oaks and coniferous trees. In the steppes, mycorrhiza did not form on the roots of tree seedlings, and the plants died. Some immediately, others a few years later, others eked out a miserable existence. Then the scientists proposed, when planting, along with seedlings, to introduce forest soil from the areas where these plants grew. Plants in this case began to grow much better.

The same thing happened when trees were planted on waste heaps, dumps during the development of ore deposits, and during the reclamation of contaminated areas. It has now been proven that the introduction of forest soil (and with it fungal hyphae) favorably affects the survival rate of young trees and is an important condition for their successful cultivation in treeless areas. The possibility of stimulating mycorrhiza formation due to local fungi present in soils, by selecting a number of agrotechnical methods (loosening, watering, etc.), was also revealed. A method has also been worked out for introducing pure cultures of mycorrhiza-forming fungi together with seedlings and seeds.

At first glance, it may seem that mushrooms live only in forests and soils rich in organic matter. However, this is not the case; they are found in all types of soils, including deserts. There are few of them only in soils where mineral fertilizers and herbicides are abused, and they are completely absent in soils devoid of fertility and treated with fungicides.

Mushroom spores are so small that they are carried by the wind over long distances. Under favorable conditions, spores germinate and give rise to a new generation of fungi. Especially favorable for the development of fungi are moist soils rich in organic matter.

Can all fungi form mycorrhiza, i.e. live with plants? Among the huge variety of fungi (and according to various estimates there are 120-250 thousand species), about 10 thousand species are phytopathogens, the rest are saprophytic fungi and mycorrhiza-forming fungi.

Mushrooms - saprophytes live in the surface layer of the soil, among a large amount of dead organic matter. They have special enzymes that allow them to decompose plant litter (mainly cellulose and lignin), and, accordingly, provide themselves with food. The role of saprophyte fungi can hardly be overestimated. They process a huge mass of organic residues - leaves, needles, branches, stumps. They are active soil formers, as they process a huge amount of dead vegetation. Fungi free the surface of the soil and prepare it for the colonization of new generations of vegetation. The released minerals are re-consumed by the plants. Saprophytic fungi abound in forest litter, peat bogs, humus, and soils rich in organic matter. Forest soils are completely permeated with the mycelium of these fungi. So, in 1 gram of soil, the length of the hyphae of these fungi reaches a kilometer or more.

Mycorrhizal fungi do not have such enzymes, which is why they cannot compete with fungi that decompose dead vegetation. Therefore, they have adapted to coexistence with the roots of plants, where they receive the food they need.

What is mycorrhiza, and what fungi form it? The fungus with its threads (hyphae) braids the root, forming a kind of sheath up to 40 microns thick there. The thinnest threads stretch from it in all directions, penetrating the soil for tens of meters around the tree. Some types of fungi remain on the surface of the root, others grow inside it. Still others represent a transitional form intermediate between them.

Mycorrhiza, which braids the root, is characteristic of woody plants and perennial herbs. It is formed mainly by cap mushrooms: boletus, boletus, porcini mushrooms, russula, fly agaric, pale grebe, etc. That is, both edible and poisonous mushrooms for humans. For plants, all mushrooms are useful and necessary, regardless of their taste. Therefore, in no way should you destroy mushrooms, including poisonous ones.

Cap mushrooms, such as oyster mushrooms, mushrooms, champignons, umbrellas, dung beetles, are saprophytes (i.e., they feed on wood, manure or other organic matter), they do not form mycorrhiza.

The mushrooms that we collect in the forest are mycorrhiza fruiting bodies. Mushrooms are somewhat reminiscent of an iceberg, the apical part of which is represented by fruiting bodies (mushrooms in the everyday sense), necessary for the formation and spread of spores. The underwater part of the iceberg is mycorrhiza, which braids the roots of plants with its threads. It sometimes stretches for tens of meters. This can be judged at least by the size of the "witch rings".

In other fungi, the hyphae penetrate the tissues and cells of the root, receiving food for themselves from there. This is not carried out without the participation of the plant, because. in this case, the process of transferring nutrients is easier. In the presence of such fungi, plant roots undergo significant morphological changes, they branch intensively, forming special protrusions and outgrowths. This occurs under the action of growth substances secreted by fungi (auxins). This is the most common type of mycorrhiza in herbaceous plants and some woody (apple, maple, elm, alder, lingonberry, heather, orchid, etc.).

Some plants, such as orchids, heather, can develop normally only in the presence of mycorrhizal fungi. In others (oak, birch, conifers, hornbeam) - mycotrophy occurs almost always. There are plants (acacia, linden, birch, some fruit trees, many shrubs) that can develop normally both with mushrooms and in their absence. This largely depends on the availability of nutrients in the soil; if there are a lot of them, then the need for mycorrhiza disappears.

A strong connection is established between the plant and fungi, and very often certain types of fungi are also characteristic of certain groups of plants. Most host plants do not have a strict specialization towards fungi. They can form mycorrhiza with several fungal species. For example, boletus, porcini mushroom, red mushroom, volnushka, milk mushrooms, russula, red fly agaric and others develop on a birch. On the aspen - boletus, russula, aspen breast. On different types of spruce - butterdish, white mushroom, camelina, yellow pickle, types of russula and cobwebs, different types of fly agaric. On the pine - white mushroom, Polish mushroom, real butter dish, granular butter dish, flywheel, russula, camelina, fly agaric. However, there are plants that are "served" by only one fungus. For example, larch butterdish creates mycorrhiza only with larch.

At the same time, there are also so-called universal mushrooms (among which, oddly enough, the red fly agaric), which are able to create mycorrhiza with many trees (both coniferous and deciduous), shrubs and herbs. The number of mushrooms that "serve" certain trees is different. So in pine there are 47 species, in birch - 26, in spruce - 21, in aspen - 8, and in linden - only 4.

Why is mycorrhiza useful for higher plants? The mycelium of the fungus replaces the root hairs of the plant. Mycorrhiza is, as it were, a continuation of the root itself. When mycorrhiza appears in many plants, due to the lack of need, root hairs do not form. The mycorrhizal cover with numerous fungal hyphae extending from it significantly increases the surface of absorption and supply of plants with water and minerals. For example, in 1 cm 3 of the soil surrounding the root, the total length of the mycorrhiza threads is 20-40 meters, and they sometimes go away from the plant for tens of meters. The absorbing surface of the branched filaments of the fungus in mycorrhiza is 1000 times larger than the surface of the root hairs, which sharply increases the extraction of nutrients, as well as water from the soil. In mycorrhizal plants, a more intensive exchange of nutrients with the soil is observed. In the mushroom cover accumulate in in large numbers phosphorus, nitrogen, calcium, magnesium, iron, potassium and other minerals.

Threads (hyphae) of fungi are much thinner than root hairs and are about 2-4 microns. Due to this, they can penetrate into the pores of soil minerals, where there are minute amounts of pore water. In the presence of fungi, plants tolerate drought much better, because fungi extract water from the smallest pores, from where plants cannot get it.

Fungal hyphae secrete various organic acids (malic, glycolic, oxalic) into the medium and are capable of destroying soil minerals, in particular limestone, marble. They are too tough for even such durable minerals as quartz and granite. By dissolving minerals, they extract from them the mineral elements of plant nutrition, including such as phosphorus, potassium, iron, manganese, cobalt, zinc, etc. Plants without fungi are unable to extract these elements from minerals on their own. These minerals are found in mycorrhiza in combination with organic substances. Due to this, their solubility is reduced, and they are not washed out of the soil. In this way, balanced diet plants, which is provided by the development of mycorrhiza, stimulates their harmonious development, which affects productivity and ability to withstand unfavorable factors environment.

In addition, fungal hyphae provide plants with vitamins, growth hormones, some enzymes and other substances useful for plants. This is especially important for some plants (for example, corn, onions) that lack root hairs. Many types of mycorrhizal fungi secrete antibiotics and thus protect plants from pathogens. With antibiotics, they protect their habitat, and with it the root of the plant. Many fungi form and release growth-stimulating substances into the environment, which activate the growth of roots and above-ground organs, accelerate the processes of metabolism, respiration, etc. In this way, they stimulate the release of the nutrients they need by the plant. Consequently, fungi with the products of their vital activity activate the activity of the root system of plants.

And what do mushrooms get in return? It turns out that plants donate up to 20-30% (according to some sources, up to 50%) of the organic matter synthesized by them to fungi, i.e. they feed mushrooms with easily digestible substances. Root secretions contain sugars, amino acids, vitamins and other substances.

Studies have shown that mycorrhizal fungi are completely dependent on the plants with which they form mycorrhiza. Indeed, it has long been noted that the appearance of fruiting bodies of fungi occurs only in the presence of plants - symbionts. This phenomenon has been noted for russula, cobwebs, and especially for tubular mushrooms - porcini, boletus, boletus, saffron mushrooms, fly agaric. Indeed, after cutting down the trees, the fruiting bodies of the accompanying mushrooms also disappear.

It has been established that there are complex relationships between fungi and plants. Mushrooms with their secretions stimulate the physiological activity of plants and the intensity of excretion of nutrients for fungi. On the other hand, the composition of the fungal community in the rhizosphere can be regulated due to substances secreted by plant roots. Thus, plants can stimulate the growth of fungi - antagonists of phytopathogens. Fungi that are dangerous to plants are inhibited not by the plants themselves, but by antagonist fungi.

However, in the plant community, as well as among people, conflicts are possible. If a stable plant community is introduced the new kind(on its own or planted there), the mycorrhiza prevailing in this community can get rid of this plant. It will not supply him with nutrients. A plant of this objectionable species will gradually weaken and eventually die.

You and I have planted some kind of tree and we are surprised that it grows poorly, not knowing about the “undercover” struggle. This has a certain ecological meaning. A new plant, having established itself in a new community for itself, sooner or later will “bring” along its own mycorrhiza, which will be an antagonist to the existing one. Isn't that what happens in human society? The new boss always brings his “team”, which most often comes into conflict with the established team.

Further research led to even more surprises, the role of mycorrhiza in the plant community. It turns out that the hyphae of fungi, intertwining with each other, are able to form the so-called "communication networks" and connect one plant with another. Plants with the help of fungi can exchange nutrients and various stimulants with each other. A kind of mutual aid was discovered, when stronger plants feed the weak ones. This allows plants, being at some distance, to interact with each other. Plants with very small seeds are especially in need of this. The microscopic seedling could not have survived if it had not been taken care of at first by the general nutrient network. The exchange of nutrients between plants has been proven by experiments with radioactive isotopes. Special experiments have shown that seedling plants grown by self-sowing near the parent plant develop better than isolated or transplanted ones. It is possible that the seedlings are connected to the mother plant through a fungal "umbilical cord" through which the adult plant feeds the small sprout. However, this is possible only in natural biocenoses with established symbiotic relationships.

In such "communication networks" communication is not only trophic, but also informational. It turns out that plants distant from each other, with a certain impact on one of them, react to this impact instantly and in the same way. Information is transmitted through the transfer of specific chemical compounds. This is somewhat reminiscent of the transmission of information through our nervous system.

These experiments showed that the plants in the community are not just plants growing side by side, but a single organism, connected into a whole by an underground network of numerous finest fungal filaments. Plants are "interested" in a stable community, which allows them to resist the invasion of aliens.

After reading, a natural desire immediately arises to improve the life of their garden and horticultural crops through mycorrhiza. What needs to be done for this? There are many various ways, the essence of which is to introduce a small amount of “forest” land into the root system of a cultivated plant, where mycorrhizal fungi are presumably present. It is possible to introduce a pure culture of mycorrhizal fungi, which are commercially available, into the root system, which is quite expensive. However, in our opinion, the most in a simple way is next. Caps of well-ripened (old, wormy) mushrooms are collected, and it is desirable different types, including the inedible ones. They are placed in a bucket of water, stirred to wash off the spores on them, and garden and horticultural crops are watered with such water.

During the implementation of the project, state support funds were used, allocated as a grant in accordance with the order of the President Russian Federation dated March 29, 2013 No. 115-rp”) and on the basis of a competition held by the Knowledge Society of Russia.

A.P. Sadchikov,
Moscow Society of Naturalists
http://www.moip.msu.ru
[email protected]

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Views: 4831

21.03.2018

Every year the population of people on Earth increases. If the growth dynamics does not undergo any changes, then the milestone of 8 billion inhabitants of the planet will be overcome already in 2024, and scientists from the UN claim that by 2100 the world's population will already be 11 billion (!) People. Therefore, the problem of food security is already extremely acute for humanity today.

Technologies used in agriculture currently, the main focus is on the use of high performance varieties and the use of chemically produced fertilizers and growth promoters. However, in the near future, as most scientists predict, the maximum limit of their effectiveness will be reached, so farmers around the world today are faced with the search for new and non-standard solutions Problems.

One of these solutions is based on the direct use of the capabilities of the earth's ecosystem, including living microorganisms, organic matter and minerals. Microscopic organisms and fungi are literally right under our feet, and they have huge potential to bring real benefits and economically viable benefits to agriculture.

The fact is that all higher plants and fungi are closely interconnected, being elements of one natural system, thus creating a kind of symbiosis that plays a significant role in the life of most cultures.

What is mycorrhiza?

Mycorrhiza or fungus root is a symbiotic association of fungal mycelium with the roots of higher plants. This term was first introduced by Albert Bernhard Frank back in 1885.

As it turned out, about 90% of all plant varieties that exist on earth contain mycorrhiza on their roots, which plays a significant role for their full growth and development.

Currently, scientists - agronomists put forward a scientifically based theory about the content in the soil of a special substance glomalin, which is one of the varieties of vegetable protein. As it turned out, this substance accumulates in the soil precisely due to mycorrhizal fungi. Moreover, without this substance, the existence of plants is generally impossible.

Thanks to mycorrhiza, the absorbing surface of the roots in most plants increases up to 1000 (!) times. At the same time, these fungi contribute to a significant improvement of the soil, increase the porosity of the fertile soil layer and improve the process of its aeration.

The fact is that the root system of plants releases glucose, which attracts symbionts or fungi that form mycorrhiza. Sensitively capturing sugar secretions, fungi begin to entangle the roots of plants with their hyphae, creating a mycelium, and even have the ability to penetrate deep into the culture. The meaning of this penetration is to be able to transfer nutrients to each other.

Reproducing on the roots of plants, fungi create a mass of thin absorbent threads that have the ability to penetrate into the smallest pores of minerals in the ground, thereby increasing the absorption of nutrients and moisture. Surprisingly, in one cubic centimeter there can be mycorrhiza with a total length of threads up to 40 meters (!).

These threads, destroying minerals, extract the most valuable macro and microelements from the soil (for example, phosphorus), which are then supplied to plants.

At the same time, cultures infected with the fungus are better able to resist various pathogenic infections, since mycorrhizae stimulate their protective functions.

Varieties of mycorrhiza

There are several varieties of mycorrhiza, but there are two main types:

Internal (endomycorrhiza). With internal mycorrhiza, fungi form directly in the root system of plants, so the use of endomycorrhiza is more effective and is already used in agriculture.

Most often, this type of mycorrhiza is found on cultivated garden fruit trees (apple trees, pears, and so on), it can also be found on berry and grain crops, on some types of legumes and vegetables (in particular, on tomatoes and eggplants). Endomycorrhiza is also characteristic of most ornamental crops and flowers.

External or external (ectomycorrhiza). With external mycorrhiza, the fungus braids the root from the outside, without penetrating inside it, but forming some formations around the roots like a cover (hyphae mantle).

This type of symbiosis is less effective for agricultural use, since the exchange of nutrients is mainly one-way, in which the fungus consumes the sugars (glucose) synthesized by the plant. Due to the action of special hormones secreted by the fungus, young plant roots begin to branch and thicken profusely.

However, external ectomycorrhiza provides plants with tangible benefits, helping to safely survive the harsh winter time, because together with sugars, the fungus takes away excess moisture from the plant.

Most often, external ectomycorrhiza can be found in forests (in oak forests, birch groves, willows, poplars, maples, and so on, but it is especially characteristic of coniferous species plants), where fungi create a dense mycelium around the root system of trees.

Stages of germination of endomycorrhiza

At first, fungal spores form special attachments to the root system of plants in the form of growths (suction cups), which are called appressors. Gradually, from these formations, a hypha (a special process coming from the mycelium) begins to penetrate into the root. The hyphae is able to pierce the outer epidermis, thus getting into the internal tissues of the root system, where it begins to branch, forming a mushroom mycelium. The hyphae then penetrate into plant cells, where arbuscules are created in the form of complex branches, in which an intensive exchange of nutrients takes place.

Arbuscules can exist for several days, and then dissolve, while instead of old hyphae, new arbuscules begin to form. This process is programmed, controlled by a special set of genes, and is a hereditary system model responsible for the reproduction of mycorrhiza.

Mycorrhiza in the service of man

Due to the fact that mycorrhizae have a positive effect on plants, contributing to their rapid growth and development, these fungi are increasingly used in agriculture, horticulture and forestry.

Alas, scientists have not yet learned how to control the behavior of mycorrhiza, so they are not yet amenable to change and are poorly controlled. Nevertheless, even today mycorrhiza is actively used by some farms to support the growth and development of plants (especially young ones).

Mycorrhiza fungi are also used on heavily depleted soils and in regions experiencing regular problems with irrigation water. In addition, they are effectively used in regions where man-made disasters have occurred, since fungi successfully resist various pollution, including extremely toxic ones (for example, mycorrhiza perfectly neutralizes the negative impact of heavy metals).

Among other things, this type of fungus perfectly fixes nitrogen and solubilizes phosphorus, turning it into a form that is more accessible and well absorbed by plants. Of course, this fact affects the yield of crops, moreover, without the use of expensive fertilizers.

It has been noticed that plants treated with mycorrhiza give more friendly seedlings, their root system develops better, and consumer qualities and fruit sizes improve. At the same time, all products are exclusively environmentally friendly, natural.

In addition, plants treated with mycorrhiza show resistance to pathogenic organisms.

Currently, there are a lot of drugs that process plant seeds that show a positive effect.

Endomycorrhizal mushrooms are great for improving the nutrition of vegetables, ornamental plants and fruit trees.

Especially valuable is the experience of gardeners from the United States, who chose land completely devoid of fertility for planting fruit trees. The use of mycorrhizal preparations allowed scientists, even under such unfavorable conditions, to create a flowering garden in this place after a while.

Beneficial features mycorrhiza

Saves moisture (up to 50%)

Accumulates useful macro and microelements, which improves the growth and development of plants

Increases plant resistance to adverse climatic and weather conditions, and also resists salts and heavy metals, leveling the strong contamination of the soil with toxins

Increases productivity, improves the presentation and taste of fruits

Helps to resist various pathogens and harmful organisms (for example, the fungus is effective against nematodes). Some varieties of fungi can suppress up to 60 varieties of pathogens that cause rot, scab, late blight, fusarium and other diseases.

Enhances plant immunity

Helps speed up the flowering process

Accelerates the process of survival of crops and has a positive effect on the growth of green mass

In fact, mycorrhiza has existed in nature for 450 million years and still works effectively, helping to diversify modern views cultures.

Mycorrhiza works on the principle of a pump, absorbing water from the soil and extracting useful substances from the soil, and in return, receiving vital carbohydrates for itself. Its spores can spread tens of meters, covering a much larger area than conventional cultures can afford. Therefore, thanks to such close cooperation, plants bear fruit better, show resistance to various diseases well tolerated adverse weather conditions and poor soils.

The future of mycorrhiza? Time will show.

In order to visualize more clearly what the mycorrhiza of tree roots looks like, it is necessary to compare the appearance of root endings with mycorrhiza with the appearance of roots without it. The roots of the warty euonymus, for example, devoid of mycorrhiza, branch sparsely and are the same throughout, in contrast to the roots of rocks that form mycorrhiza, in which the sucking mycorrhizal endings differ from the growth, not mycorrhizal ones. Mycorrhizal sucking endings either swell club-shaped at the tip in oak, or form very characteristic "forks" and complex complexes of them, resembling corals, in pine, or have the shape of a brush in spruce. In all these cases, the surface of the sucking endings greatly increases under the action of the fungus. Having made a thin cut through the mycorrhizal end of the root, one can be convinced that the anatomical picture is even more diverse, i.e., the sheath of fungal hyphae braiding the root end can be of different thickness and color, be smooth or fluffy, consisting of such dense intertwined hyphae, which gives the impression of real tissue or, conversely, be loose.

It happens that the cover does not consist of one layer, but of two, differing from each other in color or structure. The so-called Hartig network can also be expressed to varying degrees, i.e., hyphae that go along the intercellular spaces and form together really something like a network. IN different occasions this network may extend to more or fewer layers of root parenchyma cells. The hyphae of the fungus partially penetrate into the cells of the cow parenchyma, which is especially pronounced in the case of aspen and birch mycorrhiza, and are partially digested there. But no matter how peculiar the picture of the internal structure of mycorrhizal roots, in all cases it is clear that the hyphae of the fungus do not enter the central cylinder of the root and the meristem at all, i.e., into that zone of the root ending where, due to increased cell division, the root grows. . All such mycorrhiza are called ectoendotrophic, since they have both a superficial sheath with hyphae extending from it, and hyphae passing inside the root tissue.

Not all tree species have mycorrhiza of the types described above. In maple, for example, mycorrhiza is different, that is, the fungus does not form an outer cover, but in the cells of the parenchyma one can see not separately running hyphae, but whole balls of hyphae, often filling the entire space of the cell. Such mycorrhiza is called endotrophic (from the Greek "endos" - inside, and "trophe" - nutrition) and is especially characteristic of orchids. Appearance mycorrhizal endings (shape, branching, depth of penetration) are determined by the tree species, and the structure and surface of the cover depend on the type of fungus that forms mycorrhiza, and, as it turned out, not one, but two fungi can simultaneously form mycorrhiza.

What fungi form mycorrhiza and with what breed? It was not easy to resolve this issue. IN different time various methods have been proposed for this, up to careful tracing of the course of fungal hyphae in the soil from the base of the fruiting body to the root end. by the most effective method turned out to be sowing under sterile conditions of a certain type of fungus in the soil on which a seedling of a certain tree species was grown, that is, when mycorrhiza was synthesized under experimental conditions. This method was proposed in 1936 by the Swedish scientist E. Melin, who used a simple chamber consisting of two flasks connected to each other. In one of them, a sterile pine seedling was grown and a fungus was introduced in the form of mycelium taken from a young fruiting body at the transition point of the cap to the stem, and in the other there was a liquid for the necessary soil moisture. Subsequently, scientists who continued to work on the synthesis of mycorrhiza made various improvements to the structure of such a device, which made it possible to conduct experiments under more controlled conditions and for a longer time.

When using the Melin method, by 1953, the relationship of tree species with 47 species of fungi from 12 genera was experimentally proven. To date, it is known that mycorrhiza with tree species can form more than 600 species of fungi from such genera as fly agaric, rowing, hygrophores, some lactic (for example, milk mushrooms), russula, etc., and it turned out that each can form mycorrhiza not with one, but with different tree species. In this regard, all records were broken by the marsupial fungus, which has sclerotia, granular coenococcus, which, under experimental conditions, formed mycorrhiza with 55 species of tree species. The greatest specialization is characterized by sublarch butterdish, which forms mycorrhiza with larch and with cedar pine.

Some genera of fungi are not able to form mycorrhiza - govorushki, kollybia, omfalia, etc.

And yet, despite such a wide specialization, the effect of different mycorrhiza-forming fungi on a higher plant is not the same. So, in the mycorrhiza of Scots pine, formed by the butter dish, the absorption of phosphorus from hard-to-reach compounds occurs better than when the fly agaric participates in the formation of mycorrhiza. There are other facts that confirm this. It is very important to take this into account in practice and when accepting the mycorrhization of tree species for their better development it is necessary to select such a mushroom for a particular breed, which would have the most beneficial effect on it.

It has now been established that mycorrhizal hymenomycetes do not form fruiting bodies under natural conditions without connection with tree roots, although their mycelium can exist saprotrophically. That is why until now it was impossible to grow milk mushrooms, mushrooms, porcini mushroom, boletus and other valuable types of edible mushrooms in the beds. However, in principle this is possible. Someday, even in the not too distant future, people will learn to give the mycelium all that it gets from cohabitation with the roots of trees, and make it bear fruit. In any case, such experiments are being conducted under laboratory conditions.

As for tree species, spruce, pine, larch, fir, and possibly most other conifers are considered to be highly mycotrophic, and oak, beech and hornbeam from deciduous species. Birch, elm, hazel, aspen, poplar, linden, willow, alder, mountain ash, bird cherry are weakly mycotrophic. These tree species have mycorrhiza in typical forest conditions, but in parks, gardens, and when growing as individual plants, they may not have it. In such fast-growing species as poplar and eucalyptus, the absence of mycorrhiza is often associated with their rapid consumption of carbohydrates formed during intensive growth, i.e., carbohydrates do not have time to accumulate in the roots, which is necessary condition for the settlement of the fungus on them and the formation of mycorrhiza.

What are the relationships between the components in mycorrhiza? One of the first hypotheses about the nature of mycorrhiza formation was proposed in 1900 by the German biologist E. Stahl. It was as follows: in the soil there is fierce competition between various organisms in the struggle for water and mineral salts. It is especially pronounced in the roots of higher plants and mycelium of fungi in humus soils, where there are usually a lot of fungi. Those plants that had a powerful root system and good transpiration did not suffer much in the conditions of such competition, and those with a relatively weak root system and low transpiration, i.e. plants that were not able to successfully absorb soil solutions, left the predicament, forming mycorrhiza with a powerfully developed system of hyphae penetrating the soil and increasing the absorption capacity of the root. The most vulnerable point of this hypothesis is that there is no direct relationship between the absorption of water and the absorption of mineral salts. Thus, rapidly absorbing and rapidly evaporating water plants are not the most armed in the competition for mineral salts.

Other hypotheses were based on the ability of fungi to act with their enzymes on the lignin-protein complexes of the soil, destroy them and make them available to higher plants. There were also suggestions, which were confirmed later, that the fungus and the plant can exchange growth substances, vitamins. Fungi, as heterotrophic organisms that need ready-made organic matter, receive primarily carbohydrates from a higher plant. This was confirmed not only by experiments, but also by direct observations. For example, if trees grow in heavily shaded places in the forest, the degree of mycorrhiza formation is greatly reduced, since carbohydrates do not have time to accumulate in the roots in the proper amount. The same applies to fast-growing tree species. Consequently, in sparse forest plantations, mycorrhiza forms better, faster and more abundantly, and therefore the process of mycorrhiza formation can improve during thinning.

Fungi that envelop the roots of the host plant require soluble carbohydrates as a source of carbon, and in this respect they differ from most of their free-living, that is, non-symbiotic relatives that break down cellulose. Mycorrhizal fungi do at least part of their carbon requirements come from their hosts. The mycelium absorbs mineral nutrients from the soil, and at present there is no doubt that it actively supplies them to the host plant. In studies using radioactive labels, it was found that phosphorus, nitrogen and calcium can get into the roots through the hyphae of fungi, and then into the shoots. Surprisingly, the mycorrhiza does not appear to be less effective without the hyphae extending from the mycelium "sheath" enveloping the root. Therefore, this “sheath” itself must have well-developed abilities to absorb nutrients and transfer them to the plant.[ ...]

Mycorrhizal cohabitation (symbiosis) is mutually beneficial for both symbionts: the fungus extracts additional, inaccessible nutrients and water from the soil for the tree, and the tree supplies the fungus with the products of its photosynthesis - carbohydrates.[ ...]

Fungi that enter into symbiosis with forest trees, most often belong to the group of basidiomycetes - hat mushrooms, combining both edible and inedible species. The mushrooms that we collect with such enthusiasm in the forest are nothing more than the fruiting bodies of mushrooms associated with roots. various trees. It is curious that some mycorrhizal fungi prefer one kind of tree, others - several, and their list may include both coniferous and deciduous trees.[ ...]

Mycorrhizal symbiosis "fungi - plant roots" is another important adaptive mechanism that has developed as a result of low bioavailability of phosphorus. The fungal component of symbiosis increases the absorbing surface, but is not able to stimulate sorption by chemical or physical influences. The phosphorus of fungal hyphae is exchanged for carbon fixed by the symbiotic plant.[ ...]

E who mycorrhizal fungi need soluble carbohydrates.[ ...]

Pain fungi can form mycorrhiza with one, several or even many tree species, sometimes systematically very distant from each other (for example, with conifers and deciduous trees). But it is often observed that a fungus of one species or another is confined to trees of only one species or one genus: larch, birch, etc. Within the same genus - to individual species - they usually turn out to be "insensitive". However, in the case of the pine genus (Rtiv), there is a greater confinement not to the entire genus as a whole, but to its two subgenera: two-needle pines (for example, Scotch pine) and five-needle pines (for example, Siberian cedar). It is impossible not to note such cases when some mycorrhizal fungi, isolated from tree roots, can apparently develop as saprophytes, content with the litter (falling needles, leaves, rotten wood) of those tree species with which they usually form hikorizu. For example, white fungus was found on top of a huge boulder in a pine forest, Asian boletus (a companion of larch) - on a high, rotten stump of a birch growing in a larch forest.[ ...]

M. plants and mycorrhizal fungi. These relationships with fungi are characteristic of most species of vascular plants (flowering, gymnosperms, ferns, horsetails, club mosses). Mycorrhizal fungi can braid the root of the plant and penetrate into the tissues of the root without causing significant damage to it. Fungi incapable of photosynthesis obtain organic substances from the roots of plants, and in plants, due to the branched fungal filaments, the absorptive surface of the roots increases hundreds of times. In addition, some mycorrhizal fungi not only passively absorb nutrients from the soil solution, but also simultaneously act as decomposers and break down complex substances into simpler ones. Through mycorrhiza, organic substances can be transmitted from one plant to another (of the same or different species).[ ...]

There are also mycorrhizal fungi cohabiting with the roots of higher plants. The mycelium of these fungi envelops the roots of plants and helps to obtain nutrients from the soil. Mycorrhiza is observed mainly in woody plants with short sucking roots (oak, pine, larch, spruce).[ ...]

These are mushrooms of the genera Elaphomyces and truffle (Tuber). The last genera form mycorrhiza with woody plants - beech, oak, etc.[ ...]

In the case of endotrophic mycorrhiza, the relationship between the fungus and the higher plant is even more complex. Due to the low contact of the hyphae of the mycorrhizal fungus with the soil, a relatively small amount of water, as well as mineral and nitrogenous substances, enters the root in this way. In this case, biologically active substances such as vitamins, produced by the fungus, probably become important for the higher plant. In part, the fungus supplies the higher plant with nitrogenous substances, since part of the hyphae of the fungus, located in the root cells, is digested by them. The fungus gets carbohydrates. And in the case of orchid mycorrhiza, the fungus itself gives carbohydrates (in particular, sugar) to the higher plant.[ ...]

Almost all types of trees under normal conditions cohabit with mycorrhizal fungi. The mycelium of the fungus wraps around the thin roots of the tree with a sheath, penetrating into the intercellular space. The mass of the finest fungal filaments extending a considerable distance from this sheath successfully performs the function of root hairs, absorbing the nutrient soil solution.[ ...]

One of the most common species of this genus and the entire family is the white fungus (V. edulis, table 34). It is the most nutritionally valuable of all edible mushrooms in general. It has about two dozen forms, differing mainly in the color of the fruiting body and mycorrhizal confinement to a particular tree species. The hat is whitish, yellow, brownish, yellow-brown, red-brown or even almost black. The spongy layer in young specimens is pure white, later yellowish and yellowish-olive. On the leg there is a light mesh pattern. The pulp is white, does not change at the break. It grows with a lot of tree species - coniferous and deciduous, in the middle zone of the European part of the USSR - more often with birch, oak, pine, spruce, but has never been noted in the USSR with such a common species as larch. In the arctic and mountain tundra occasionally grows with dwarf birch. The species is Holarctic, however, in the cultures of the corresponding tree species, it is also known outside the Holarctic (for example, Australia, South America). It grows in abundance in places. In the USSR, white fungus lives mainly in the European part, in Western Siberia, in the Caucasus. It is very rare in Eastern Siberia and the Far East.[ ...]

The roots of the grasshoppers are thick and fleshy, retracting in many species. The cells of the root bark usually contain a mycorrhizal fungus belonging to phycomycetes. These mycorrhizal roots lack root hairs.[ ...]

The role of mycorrhiza is very great in tropical rainforests, where the absorption of nitrogen and other inorganic substances occurs with the participation of a mycorrhizal fungus that feeds on saprotrophs on fallen leaves, stems, fruits, seeds, etc. The main source of minerals here is not the soil itself, but soil fungi . Mineral substances enter the porcini directly from the hyphae of mycorrhizal fungi. In this way, a more polyoo use of mineral substances and their more complete cycle are ensured. Impossibly, it is explained that most of the root system of rainforest plants is located in the surface layer of the soil at a depth of about 0.3 m.[ ...]

It should also be noted that in artificially created forest plantations from a particular tree species, the accompanying them are especially characteristic species mycorrhizal fungi are sometimes found very far from the boundaries of their natural range. In addition to tree species, the type of forest, the type of soil, its moisture content, acidity, etc. [ ...]

The real mushroom is found in birch and pine-birch forests with linden undergrowth. large groups("flocks"), from July to September. Mandatory mycorrhizal mushroom with birch.[ ...]

Mutualism is a widespread form of mutually beneficial relationships between species. Lichens are a classic example of mutualism. Symbionts in lichen - fungus and algae - physiologically complement each other. The hyphae of the fungus, braiding the cells and threads of algae, form special suction processes, haustoria, through which the fungus receives substances assimilated by algae. Algae get minerals from water. Many grasses and trees normally exist only in cohabitation with soil fungi that settle on their roots. Mycorrhizal fungi promote the penetration of water, mineral and organic substances from the soil into the roots of plants, as well as the absorption of a number of substances. In turn, they receive from the roots of plants carbohydrates and other organic substances necessary for their existence.[ ...]

One of the measures against acidification of forest soils is their liming in the amount of 3 t/ha every 5 years. It may be promising to protect forests from acid rain with the help of some types of mycorrhizal fungi. The symbiotic community of fungal mycelium with the root of a higher plant, expressed in the formation of mycorrhiza, can protect trees from the harmful effects of acidic soil solutions and even significant concentrations of certain heavy metals, such as copper and zinc. Many mycorrhiza-forming fungi have an active ability to protect trees from the effects of drought, which are especially detrimental to trees growing in conditions of anthropogenic pollution.[ ...]

Russula graying (R. decolorans) has a cap at first spherical, spherical, then prostrate, flat-convex and depressed, yellow-brown, reddish-orange or yellowish-orange, more or less reddish, lilac or pinkish along the edge, unequally fading, with scattered red spots, 5-10 cm in diameter with a thin, slightly striated edge. The plates are adherent, white, then yellow. These mushrooms are found mainly in pine forests of the green moss type. Mandatory as mycorrhizal mushrooms with pine. The taste is sweet, then spicy.[ ...]

Most of the elements of mineral nutrition enter the organisms of the forest and the entire biota of the ecosystem exclusively through the roots of plants. Roots extend into the soil, branching into thinner and thinner endings, and thus cover a sufficiently large volume of soil, which provides large surface absorption of nutrients. The surface area of ​​the roots of the community was not measured, and it can be assumed that it exceeds the surface area of ​​the leaves. In any case, nutrients mainly enter the community not through the surface of the roots themselves (and not through the root hairs for most plants), but through the surface of fungal hyphae, which is significantly predominant in area. The surface of the predominant part of the roots is mycorrhizal (that is, covered with fungal mycelium that is in symbiosis with the root), and the hyphae of these fungi extend from the roots into the soil; For most terrestrial plants, fungi are mediators in the absorption of nutrients.[ ...]

The function of ecosystems includes a complex hallmarks metabolism - transfer, transformation, use and accumulation of inorganic and organic substances. Some aspects of this metabolism can be studied using radioactive isotopes, such as radioactive phosphorus: their movements in the aquatic environment (aquarium, lake) are monitored. Radioactive phosphorus circulates very quickly between water and plankton, more slowly penetrates coastal plants and animals, and gradually accumulates in bottom sediments. When phosphate fertilizers are applied to a lake, there is a temporary increase in its productivity, after which the concentration of phosphates in the water returns to the level that was before the application of fertilizer. Nutrient transfer brings together all parts of an ecosystem, and the amount of nutrients in water is determined not only by its supply, but also by the overall function of the ecosystem at a steady state. In the forest ecosystem, nutrients from the soil enter the plants through mycorrhizal fungi and roots and are distributed to various plant tissues. Most of the nutrients go to the leaves and other short-lived tissues, which ensures that the nutrients return to the soil after a short time and thus complete the cycle. Nutrients also enter the soil and into the soil as a result of their washing off from the leaves of plants. Organic substances are also washed off the surface of the leaves into the soil, and some of them have an inhibitory effect on other plants. Chemical inhibition of some plants by others is only one of the manifestations of the allelochemical influence, the chemical effects of some species on others. The most widespread variant of such influences is the use of chemical compounds by organisms for defense against their enemies. Three large groups of substances take part in the metabolism of communities: inorganic nutrients, food (for heterotrophs) and allelochemical compounds.[ ...]

Modern ferns, the geological history of which dates back to the Carboniferous (Permo-Carboniferous genus Psaronius - Rzagopshe - and others). Perennial plants varying from small forms to very large ones. The stems are dorsiventral corpus or thick tuberous trunks. The stems are fleshy. In the stems, as in other vegetative organs, there are large lysigenic mucus ducts, which are one of the features of maratthioisids. In large forms, a dictyostele of a very complex structure is formed (the most complex in the genus Angiopteris - Angiopteris). Tracheids are scalariform. In the genus Angiopteris, a very weak development of secondary xylem is observed. The roots bear peculiar multicellular root hairs. The first roots to form usually contain a mycorrhizal phycomycete fungus in the bark. Young leaves are always spirally twisted. Very characteristic is the presence at the base of the leaves of two thick stipules, connected together by a special transverse bridge.[ ...]

The ability of green plants to carry out photosynthesis is due to the presence of pigments in them. The maximum absorption of light is carried out by chlorophyll. Other pigments absorb the rest, converting it into different kinds energy. In an angiosperm flower, due to pigmentation, the solar spectrum with a certain wavelength is selectively captured. The idea of ​​two plasmas in the organic world predetermined the symbiotrophic origin of plants. Symbiotic endophytes of the Fungi imperfect class isolated from all parts of plants synthesize pigments of all colors, hormones, enzymes, vitamins, amino acids, lipids and supply them to the plant instead of carbohydrates received. The hereditary transmission of endophytes guarantees the integrity of the system. Some plant species have two types of ecto-endophytic mycorrhizal fungi or fungi and bacteria, the combination of which provides flower color, plant growth and development (Geltser, 1990).