Photo of symbiosis of mushrooms with roots
A striking example of fungal symbiosis is mycorrhiza - a community of fungi and higher plants (various trees). With such “cooperation” both the tree and the mushroom benefit. Settling on the roots of a tree, the fungus performs the function of absorbing root hairs and helps the tree absorb nutrients from the soil. With this symbiosis, the fungus receives ready-made organic substances (sugars) from the tree, which are synthesized in the leaves of the plant with the help of chlorophyll.
In addition, during the symbiosis of fungi and plants, the mycelium produces substances such as antibiotics that protect the tree from various pathogenic bacteria and pathogenic fungi, as well as growth stimulants such as gibberellin. It has been noted that trees under which cap mushrooms grow practically do not get sick. In addition, the tree and the mushroom actively exchange vitamins (mainly groups B and PP).
Many cap mushrooms form a symbiosis with roots various types plants. Moreover, it has been established that each type of tree is capable of forming mycorrhiza not with one type of fungus, but with dozens different types.
In the photo Lichen
Another example of the symbiosis of lower fungi with organisms of other species is lichens, which are a union of fungi (mainly ascomycetes) with microscopic algae. What is the symbiosis of fungi and algae, and how does such “cooperation” occur?
Until the middle of the 19th century, it was believed that lichens were separate organisms, but in 1867, Russian botanists A. S. Famintsyn and O. V. Baranetsky established that lichens are not separate organisms, but a community of fungi and algae. Both symbionts benefit from this union. Algae, with the help of chlorophyll, synthesize organic substances (sugars), which the mycelium feeds on, and the mycelium supplies the algae with water and minerals, which it sucks from the substrate, and also protects them from drying out.
Thanks to the symbiosis of fungus and algae, lichens live in places where neither fungi nor algae can exist separately. They inhabit hot deserts, high mountains and harsh northern regions.
Lichens are even more mysterious creatures of nature than mushrooms. They change all the functions that are inherent in separately living fungi and algae. All vital processes in them proceed very slowly, they grow slowly (from 0.0004 to several mm per year), and also age slowly. These unusual creatures are distinguished by a very long life expectancy - scientists suggest that the age of one of the lichens in Antarctica exceeds 10 thousand years, and the age of the most common lichens that are found everywhere is at least 50-100 years.
Thanks to the collaboration of fungi and algae, lichens are much more resilient than mosses. They can live on substrates on which no other organism on our planet can exist. They are found on stone, metal, bones, glass and many other substrates.
Lichens still continue to amaze scientists. They contain substances that no longer exist in nature and which became known to people only thanks to lichens (some organic acids and alcohols, carbohydrates, antibiotics, etc.). The composition of lichens, formed by the symbiosis of fungi and algae, also includes tannins, pectins, amino acids, enzymes, vitamins and many other compounds. They accumulate various metals. Of the more than 300 compounds contained in lichens, at least 80 of them are found nowhere else in the living world of the Earth. Every year, scientists find in them more and more new substances that are not found in any other living organisms. Currently, more than 20 thousand species of lichens are already known, and every year scientists discover several dozen more new species of these organisms.
From this example it is clear that symbiosis is not always simple cohabitation, and sometimes gives rise to new properties that none of the symbionts had individually.
There are a great many such symbioses in nature. With such a partnership, both symbionts win.
It has been established that the desire for unification is most developed in mushrooms.
Mushrooms also enter into symbiosis with insects. An interesting association is the connection between some types of molds and leaf-cutter ants. These ants specifically breed mushrooms in their homes. In separate chambers of the anthill, these insects create entire plantations of these mushrooms. They specially prepare the soil on this plantation: they bring in pieces of leaves, crush them, “fertilize” them with their feces and the feces of caterpillars, which they specially keep in the neighboring chambers of the anthill, and only then introduce the smallest fungal hyphae into this substrate. It has been established that ants breed only mushrooms of certain genera and species that are not found anywhere in nature except anthills (mainly fungi of the genera Fusarium and Hypomyces), and each species of ants breeds certain types of mushrooms.
Ants not only create a mushroom plantation, but also actively care for it: they fertilize, prune and weed. They cut off the emerging fruiting bodies, preventing them from developing. In addition, ants bite off the ends of fungal hyphae, as a result of which proteins accumulate at the ends of the bitten off hyphae, forming nodules resembling fruiting bodies, which the ants then feed on and feed their babies. In addition, when the hyphae are trimmed, the mycelium of the fungi begins to grow faster.
“Weeding” is as follows: if mushrooms of other species appear on the plantation, the ants immediately remove them.
It is interesting that when creating a new anthill, the future queen, after the nuptial flight, flies to a new place, begins to dig tunnels for the home of her future family, and creates a mushroom plantation in one of the chambers. She takes mushroom hyphae from an old anthill before flight, placing them in a special suboral pouch.
Termites are also bred in similar plantations. In addition to ants and termites, bark beetles, boring insects, some types of flies and wasps, and even mosquitoes are involved in “mushroom farming.”
German scientist Fritz Schaudin discovered an interesting symbiosis of our ordinary blood-sucking mosquitoes with actinomycetes yeast fungi, which help them in the process of sucking blood.
Currently, about 300 thousand species of plants grow on our land, of which 90% (according to other sources, even more) live in close collaboration with fungi, and these are not only trees and shrubs, but also herbs.
This relationship between plants and fungi in the scientific world is called mycorrhiza (i.e. fungal root; from the Greek. mykes- mushroom, rhiza– root). Currently, only a small part of plants (and these are certain species from the family of amaranthaceae, goosefoot, and cruciferous plants) can do without mycorrhizae, 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. Throughout their lives, orchids receive nutrition from mycorrhiza, although they have a photosynthetic apparatus and can independently synthesize organic substances.
The first who paid attention to the need for mushrooms for plants were foresters. After all, a good forest is always rich in mushrooms. The connection between mushrooms and certain trees is indicated by their names - boletus, boletus, etc. In practice, foresters encountered this only during artificial afforestation. At the beginning of the twentieth century, attempts were made to plant forests on steppe lands, especially regarding the planting of 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 after a few years, others eked out a miserable existence. Then scientists proposed adding forest soil from the areas where these plants grew when planting seedlings. In this case, the plants began to grow much better.
The same thing happened when planting trees on waste heaps, dumps during the development of ore deposits, and during the reclamation of contaminated areas. It has now been proven that the addition of forest soil (and with it fungal hyphae) has a beneficial effect on 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 the soils, through the selection of a number of agrotechnical techniques (loosening, watering, etc.), was also revealed. A method of introducing pure cultures of mycorrhizal fungi together with seedlings and seeds has also been developed.
At first glance, it may seem that mushrooms live only in forests and soils rich in organic matter. However, this is not true; they are found in all types of soils, including deserts. There are only a few of them in soils where mineral fertilizers and herbicides are abused, and they are completely absent in soils devoid of fertility and treated with fungicides.
Fungal spores are so small that they are carried long distances by the wind. IN favorable conditions the spores germinate and give rise to a new generation of mushrooms. Moist soils rich in organic matter are especially favorable for the development of fungi.
Can all fungi form mycorrhizae, 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 and mycorrhizal fungi.
Fungi - saprophytes live in surface layer soil, among large amounts 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 saprophytic fungi can hardly be overestimated. They process a huge mass of organic residues - leaves, pine needles, branches, stumps. They are active soil formers because they process huge amounts of dead vegetation. Fungi clear the soil surface and prepare it for colonization by new generations of vegetation. The released minerals are again consumed by plants. Saprophytic mushrooms inhabit forest litter, peat bogs, humus, and soils rich in organic matter in abundance. Forest soils are completely permeated with the mycelium of these fungi. Thus, 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 coexist with the roots of plants, where they receive the food they need.
What is mycorrhiza and what fungi form it? The fungus entwines the root with its threads (hyphae), forming a kind of cover up to 40 microns thick. From it, thin threads stretch 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 entwines the root, is characteristic of woody plants and perennial herbs. It is formed mainly by cap mushrooms: boletus, boletus, porcini mushrooms, russula, fly agaric, toadstool, etc. That is, both edible and poisonous mushrooms for humans. All mushrooms are useful and necessary for plants, regardless of their taste. Therefore, you should never destroy mushrooms, including poisonous ones.
Cap mushrooms, such as oyster mushrooms, honey mushrooms, champignons, umbrellas, dung beetles, are saprophytes (i.e. they feed on wood, manure or other organic matter) and do not form mycorrhizae.
The mushrooms that we collect in the forest are the fruiting bodies of mycorrhizae. 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 entwines plant roots with its threads. It sometimes stretches for tens of meters. This can be judged at least by the size of the “witch’s rings”.
In other fungi, hyphae penetrate into the tissue and cells of the root, receiving food from there. This is not done 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 influence of growth substances (auxins) secreted by fungi. This is the most common type of mycorrhiza in herbaceous plants and some trees (apple, maple, elm, alder, lingonberry, heather, orchids, etc.).
Some plants, such as orchids and heather, can develop normally only in the presence of mycorrhizal fungi. In others (oak, birch, conifers, hornbeam) mycotrophy almost always occurs. There are plants (acacia, linden, birch, some fruit trees, many shrubs), which 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 there is no need for mycorrhiza.
A strong connection is established between the plant and the fungi, and very often certain types of fungi are characteristic of certain groups of plants. Most host plants do not have strict specialization towards fungi. They can form mycorrhizae with several types of fungi. For example, boletus develops on a birch tree, White mushroom, red mushroom, volushka, milk mushrooms, russula, red fly agaric and others. On the aspen there is boletus, russula, and aspen milk mushrooms. On different types of spruce - oiler, porcini mushroom, saffron milk cap, yellow podgruzd, types of russula and cobwebs, different types of fly agarics. On the pine tree there are porcini mushrooms, Polish mushrooms, real butterflies, granular butterflies, moss mushrooms, russula, camelina, fly agaric. However, there are plants that are “served” by only one mushroom. For example, larch butterfly creates mycorrhiza only with larch.
At the same time, there are so-called universal mushrooms (among which, oddly enough, the red fly agaric), which are capable of creating mycorrhizae with many trees (both coniferous and deciduous), shrubs and herbs. The number of mushrooms that “serve” certain trees varies. So in pine there are 47 species, in birch - 26, in spruce - 21, in aspen - 8, and in linden - only 4.
How is mycorrhiza useful for higher plants? The mycelium of the fungus replaces the plant's root hairs. Mycorrhiza is like a continuation of the root itself. When mycorrhiza appears in many plants, due to lack of need, root hairs do not form. The mycorrhizal sheath with numerous fungal hyphae extending from it significantly increases the surface area for absorption and supply of water and minerals to plants. For example, in 1 cm 3 of soil surrounding the root, the total length of mycorrhizal threads is 20-40 meters, and they sometimes extend away from the plant for tens of meters. The absorbing surface of branched fungal filaments in mycorrhiza is 1000 times greater than the surface of root hairs, due to which the extraction of nutrients and water from the soil sharply increases. Mycorrhizal plants have a more intense exchange of nutrients with the soil. In the mushroom sheath they accumulate in large quantities phosphorus, nitrogen, calcium, magnesium, iron, potassium and other minerals.
Fungal threads (hyphae) 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 obtain it.
Fungal hyphae release various organic acids into the environment (malic, glycolic, oxalic) and are capable of destroying soil minerals, in particular limestone and marble. They can handle even such durable minerals as quartz and granite. By dissolving minerals, they extract from them mineral plant nutritional elements, including phosphorus, potassium, iron, manganese, cobalt, zinc, etc. Plants without fungi are independently unable to extract these elements from minerals. 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. Thus, balanced plant nutrition, which is ensured by the development of mycorrhiza, stimulates their harmonious development, which affects productivity and the ability to withstand adverse environmental factors.
In addition, fungal hyphae provide plants with vitamins, growth hormones, some enzymes and other substances beneficial to plants. This is especially important for some plants (for example, corn, onions) that lack root hairs. Many types of mycorrhizal fungi secrete antibiotics and thereby protect plants from pathogenic microorganisms. They use antibiotics to 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. By doing this, they stimulate the plant to release the nutrients it needs. Consequently, fungi, with the products of their vital activity, activate the activity of the root system of plants.
What do mushrooms get in return? It turns out that plants give fungi up to 20-30% (according to some data up to 50%) of the organic matter they synthesize, i.e. they feed the mushrooms with easily digestible substances. Root secretions contain sugars, amino acids, vitamins and other substances.
Studies have shown that mycorrhiza-forming fungi are completely dependent on the plants with which they form mycorrhiza. Indeed, it has long been noted that the appearance of fungal fruiting bodies occurs only in the presence of plants - symbionts. This phenomenon has been noted for russula, cobweb mushrooms, and especially for tubular mushrooms - porcini mushrooms, boletus mushrooms, boletus mushrooms, saffron cap mushrooms, and fly agaric mushrooms. After all, after cutting down trees, the fruiting bodies of the accompanying fungi also disappear.
It has been established that there are complex relationships between fungi and plants. Fungi 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 by substances secreted by plant roots. Thus, plants can stimulate the growth of fungi that are antagonists of phytopathogens. Fungi that are dangerous to plants are suppressed not by the plants themselves, but by antagonistic fungi.
However, in the plant community, just as among people, conflicts are possible. If it invades a stable plant community the new kind(either on its own or if it was planted there), the mycorrhiza that predominates in this community can get rid of this plant. It will not supply him with nutrients. A plant of this undesirable species will gradually weaken and eventually die.
You and I have planted a tree and are surprised that it grows poorly, not realizing the “under-the-scenes” struggle. This has a certain environmental meaning. A new plant, having established itself in a new community, will sooner or later “bring along” its characteristic mycorrhiza, which will be an antagonist of 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 existing team.
Further research led to even greater surprises about the role of mycorrhiza in the plant community. It turns out that fungal hyphae, intertwining with each other, are able to form so-called “communication networks” and communicate from one plant to 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 weaker ones. This allows plants, being at some distance, to interact with each other. Plants with very small seeds especially need this. The microscopic seedling would not have been able to survive if the general nutritional network had not initially taken it into its care. 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 mother plant develop better than those isolated or planted. Perhaps the seedlings are associated with mother plant through a fungal "umbilical cord" through which mature plant fed a small sprout. However, this is only possible in natural biocenoses with established symbiotic relationships.
In such “communication networks” the connection is not only trophic, but also informational. It turns out that plants distant from each other, when exposed to a certain influence on one of them, react to this influence 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 nearby, but a single organism connected into a whole by an underground network of numerous thin threads of fungi. Plants are “interested” in a stable community, which allows them to resist the invasion of aliens.
After reading this, a natural desire immediately arises to improve the life of your garden and vegetable crops through mycorrhiza. What needs to be done for this? There are many in various ways, the essence of which comes down to introducing into the root system cultivated plant a small amount of "forest" land where there are presumably mycorrhizal fungi. You can introduce a pure culture of mycorrhizal fungi into the root system, which are commercially available, which is quite expensive. However, in our opinion, the most in a simple way is next. Collect the caps of well-ripened (old, possibly wormy) mushrooms, preferably of different types, including inedible ones. They are placed in a bucket of water, stirred to wash away the spores on them, and garden and garden crops are watered with this water.
During the implementation of the project, state support funds allocated as a grant were used 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 Natural Scientists
http://www.moip.msu.ru
[email protected]
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1.What is mycorrhiza?
2. Mycorrhizal fungi, or symbiotrophs.
3. The role of mycorrhiza in plant life.
Mycorrhiza (from the Greek mykes - mushroom and rhiza - root), fungal root, mutually beneficial cohabitation (symbiosis) of the mycelium of the fungus with the root of a higher plant. There are ectotrophic (external) Mycorrhiza, in which the fungus entwines the integumentary tissue of the endings of young roots and penetrates into the intercellular spaces of the outermost layers of the cortex, and endotrophic (internal), which is characterized by the introduction of mycelium (fungal hyphae) into the cells. Ectotrophic Mycorrhiza is characteristic of many trees (oak, spruce, pine, birch), shrubs (willow), some shrubs (dryad) and herbaceous plants (buckwheat viviparous). Young roots of these plants usually branch, their ends thicken, the growing part of the roots is enveloped in a thick, dense fungal sheath, from which fungal hyphae extend into the soil and along the intercellular spaces into the root to the depth of one or several layers of bark, forming the so-called. Hartig network; the root hairs die off (euectotrophic type of Mycorrhiza). In the arctic shrub, an arctic and herbaceous plant, the wintergreen hyphae of the large-flowered fungus penetrate not only into the intercellular spaces, but also into the cells of the cortex (ectoendotrophic type of Mycorrhiza). Ectotrophic Mycorrhizae are most often formed by hymenomycetes (genus Boletus, Lactarius, Russula, Amanita, etc.), less often by gasteromycetes. Not one, but several species of fungi can participate in the formation of Mycorrhiza on the roots of one plant. However, as a rule, only certain mycorrhizal fungi are found in plant communities - symbionts of these plant species.
With the development of endotrophic Mycorrhiza, the shape of the roots does not change, root hairs usually do not die, a fungal sheath and a “Hartig network” are not formed; The hyphae of the fungus penetrate into the cells of the crustal parenchyma. In plants of the heather, wintergreen, lingonberry and cucumber families, the fungal hyphae in the cells form balls, which are later digested by the plant (ericoid type of Mycorrhiza). Phycomycetes (genus Endogone, Pythium) participate in the formation of this type of mycorrhiza. In plants of the orchid family, fungal hyphae from the soil penetrate into the seed, forming balls that are then digested by the cells of the seed. Of the fungi, this type of Mycorrhiza is characteristic of imperfect ones (genus Rhizoctonia) and less often - basidiomycetes (genus Armillaria, etc.). The most common in nature - in many annual and perennial grasses, shrubs and trees of various families - is the phycomycete type of Mycorrhiza, in which the hyphae of the fungus penetrate through the cells of the epidermis of the root, localizing in the intercellular spaces and cells of the middle layers of the crustal parenchyma. Mycorrhiza has a beneficial effect on the plant: due to the developed mycelium, the absorbing surface of the root increases and the flow of water and nutrients into the plant increases. Mycorrhizal fungi are probably capable of decomposing some soil organic compounds that are inaccessible to plants and producing substances such as vitamins and growth activators. The fungus uses some substances (possibly carbohydrates) that it extracts from the plant root. When cultivating forests on soil that does not contain mycorrhizal fungi, small quantities of forest soil are added to it, for example, when sowing acorns, soil from an old oak forest is added.
Mycorrhizal fungi, or symbiotrophs.
A special group of forest soil fungi consists of very numerous mycorrhizal fungi. This is one of the main groups of mushrooms in the forest. Mycorrhiza - a symbiosis of the roots of higher plants with fungi - is formed in most plants (with the exception of aquatic ones), both woody and herbaceous (especially perennial). In this case, the mycelium located in the soil comes into direct contact with the roots of higher plants. Based on how this contact occurs, three types of mycorrhizae are distinguished: endotrophic, ectotrophic and ectoendotrophic.
In endotrophic mycorrhizae, characteristic of most herbaceous plants, and especially of the orchid family, the fungus spreads mainly inside the root tissues and relatively little comes out. The roots bear normal root hairs. For most orchid species, such mycorrhiza is obligate, i.e. the seeds of these plants cannot germinate and develop in the absence of the fungus. For many other herbaceous plants, the presence of a fungus is not so necessary. Herbaceous plants enter into mycorrhizal symbiosis with microscopic fungi that do not form large fruiting bodies. In endotrophic mycorrhiza, biologically active substances such as vitamins produced by the fungus are probably of great importance for higher plants. In part, the fungus supplies the higher plant with nitrogenous substances, since part of the fungal hyphae located in the root cells is digested by them. The fungus, in turn, receives organic substances - carbohydrates - from the higher plant.
Ectotrophic mycorrhiza is distinguished by the presence of an outer sheath of fungal hyphae on the root. From this sheath, free hyphae extend into the surrounding soil. The root does not have its own root hairs. This mycorrhiza is characteristic of woody plants and is rarely found in herbaceous plants.
The transition between these types of mycorrhizae is ectoendotrophic mycorrhiza, which is more common than purely ectotrophic. Fungal hyphae with such mycorrhiza densely entwine the root from the outside and at the same time give abundant branches that penetrate into the root. This mycorrhiza is found in most tree species. In this mycorrhiza, the fungus receives carbon nutrition from the root, since it itself, being a heterotroph, cannot synthesize organic substances from inorganic ones. Its outer free hyphae diverge widely in the soil from the root, replacing the latter with root hairs. These free hyphae obtain water, mineral salts, and soluble organic substances (mainly nitrogenous) from the soil. Some of these substances enter the root, and some are used by the fungus itself to build mycelium and fruiting bodies.
Most tree species form mycorrhiza with the mycelium of cap mushrooms - macromycetes from the class of basidiomycetes, a group of orders called hymenomycetes. The soil in the forest, especially near the roots of trees, is permeated with mycorrhizal fungi, and numerous fruiting bodies of these fungi appear on the soil surface. These are pink boletus (Leccinum scabrum), red boletus (Leccinum aurantiacum), camelina (Lactarius deliciosus), many types of russula (genus Russula) and many other cap mushrooms found only in the forest. There are significantly fewer mycorrhizal fungi in the group of orders Gasteromycetes. These are mainly species of the genus Scleroderma. The common puffball (see description of the common puffball) enters into a mycorrhizal symbiosis with broad-leaved species. Edible species The genus Melanogaster also forms mycorrhizae mainly with the roots of deciduous trees. Their semi-underground fruiting bodies develop on the soil under a layer of leaf litter or shallowly in the soil, usually in deciduous forests. Melanogaster dubious (M. ambiguus) is especially common in oak and hornbeam forests from May to October. Its black-brown fruit bodies, 1-3 cm in diameter, smell like garlic and have a pleasant spicy taste. A closely related species, Melanogaster broomeianus (M. broomeianus), also found in deciduous forests, has larger (up to 8 cm in diameter) brown fruiting bodies with a pleasant fruity aroma. The class of marsupial fungi (ascomycetes) also contains a small number of mycorrhizal fungi. These are mainly species with underground fruiting bodies belonging to the order Truffles (Tuberales). Black, or true, truffle (Tuber melanosporum) grows in forests along with oak, beech, hornbeam on calcareous gravelly soil, mainly in the south of France; it is not found on Russian territory. White truffle (Choiromyces meandriformis), common in Russia, grows in deciduous forests with birch, poplar, elm, linden, willow, rowan, and hawthorn. For mycorrhizal fungi, such symbiosis is mandatory. Even if their mycelium can develop without the participation of tree roots, fruiting bodies are usually not formed in this case. This is associated with the failure of attempts to artificially breed the most valuable edible forest mushrooms, such as the porcini mushroom (Boletus edulis). It forms mycorrhiza with many tree species: birch, oak, hornbeam, beech, pine, spruce.
Some types of fungi form mycorrhizae with only one specific species. Thus, the larch butterfly (Suillus grevillei) forms mycorrhiza only with larch. For trees, symbiosis with fungi is also important: experiments in forest belts and forest plantations have shown that without mycorrhiza, trees develop worse, are stunted in growth, are weakened, and are more susceptible to diseases.
The role of mycorrhiza in plant life
The existence of mycorrhizae, fungi that live on the roots of plants, has been known for quite some time. This phenomenon - a community, or symbiosis of fungi and higher plants - was discovered by scientists in the mid-19th century. However, for a long time this remained simply a known fact and nothing more. Research in recent decades has shown the enormous role it plays in plant life. The first discoveries were made using a microscope, when fungal threads were discovered entwining the roots of plants. The microscope made it possible to see another type of mycorrhiza, which lives inside the root, penetrating and growing inside the root cells. The first type was called ectomycorrhiza, that is, external mycorrhiza. It has been found on the roots of almost all woody plants. The hyphae of the fungus entwine the root, forming a continuous sheath. From this cover, thin threads stretch in all directions, penetrating the soil for tens of meters around the tree. The mushrooms that we collect in the forest are ectomycorrhizal fruiting bodies in which spores are formed. They can be likened to the underwater part of an iceberg. Anyone who wants to grow edible mushrooms on their plot must first acquire the appropriate tree, then the corresponding mycorrhiza must form on it, and only then, perhaps, fruiting bodies will grow on it. The second type of mycorrhiza is endomycorrhiza, that is, internal mycorrhiza is characteristic mainly of herbaceous plants, including most cultivated plants. It is of much more ancient origin. Both types of mycorrhiza can often be found on one plant.
When scientists found a method to identify the DNA of mycorrhizal fungi, they were amazed by their ubiquity. Firstly, it turned out that about 90% of all plant species have mycorrhizae on their roots. Secondly, it was found that mycorrhizae have existed for as long as they have existed land plants. Endomycorrhizal DNA has been found in the fossil remains of the first land plants, which are about 400 million years old. These first plants were apparently similar to lichens, representing a symbiosis of algae and fungus. The algae, through photosynthesis, creates organic substances to feed the fungus, and the fungus plays the role of a root, extracting mineral elements from the substrate on which the lichen has settled. The fungus accompanied the plant throughout its terrestrial life. Even when the plants had roots, the fungus did not leave them, helping to extract nutrients from the soil. Currently, only a few plant species have gained independence and managed to do without mycorrhiza. These are a number of species from the families Chenopodiaceae, cabbage and amaranthaceae. Actually, it is not entirely clear why this independence is needed, since mycorrhiza increases the absorptive capacity of the roots many times over.
The hyphae of the fungus are more than an order of magnitude thinner than the root hairs and therefore are able to penetrate into the finest pores of soil minerals, which are even present in each individual grain of sand. In one cubic centimeter of soil surrounding the roots, the total length of mycorrhizal threads ranges from 20 to 40 meters. Fungal threads gradually destroy soil minerals, extracting from them mineral plant nutrition elements that are not in the soil solution, including such an important element as phosphorus. Mycorrhiza plays a very significant role in supplying plants with phosphorus, as well as a number of microelements, such as zinc and cobalt. It is clear that the plant does not skimp and pays well for this service, giving mycorrhiza 20 to 30% of the carbon it absorbs in the form of soluble organic compounds.
Further research brought even more unexpected and surprising discoveries regarding the role of mycorrhiza in the plant world. It turned out that the threads of fungi, intertwined underground, can communicate one plant with another through the transfer and exchange of organic and mineral compounds. The concept of plant communities has been illuminated in a completely new light. These are not just plants growing nearby, but a single organism, connected into a single whole by an underground network of numerous thin threads. A kind of mutual aid was discovered, where stronger plants feed weaker ones. Plants with very small seeds especially need this. The microscopic seedling would not have been able to survive if the general nutritional network had not initially taken it into its care. The exchange between plants has been proven by experiments with radioactive isotopes.
Scientists have discovered several species of plants, including orchids, which throughout their lives receive nutrition almost exclusively from mycorrhiza, although they have a photosynthetic apparatus and could synthesize organic substances themselves.
Mycorrhiza helps plants tolerate stress, drought, and lack of nutrition. Scientists believe that without mycorrhizae, majestic tropical forests, forests of oaks, eucalyptus, and redwoods could not withstand the climatic stresses that are inevitable in nature.
However, in a plant community, just as in a human community, conflicts are inevitable. Mycorrhiza has a certain selectivity, and if a certain type of mycorrhiza has spread in a plant community, this does not mean that it will be equally favorable to all types of plants. It is assumed that the species composition of plant communities largely depends on the properties of mycorrhiza. For some species that do not correspond to her, she can simply survive without providing them with food. Plants of this unwanted species gradually weaken and die. For a very long time, mycorrhizal fungi could not be grown under artificial conditions. But since the 1980s these difficulties have been overcome. Firms have emerged that produce some types of mycorrhiza for sale. Ectomycorrhiza is produced for use in forest nurseries and it has been found that its introduction into the root zone significantly improves the growth of seedlings.
Do gardeners need mycorrhizal preparations? Indeed, under natural conditions, mycorrhiza is found in all soils. Its spores are so small and light that they are carried by the wind to any distance. In a healthy garden, where chemicals are not abused, mycorrhiza is always present in the soil. However, it has been established that high doses of mineral fertilizers and pesticides, especially fungicides, suppress the development of mycorrhiza. It is not found in soils deprived of fertility as a result of inept farming, as a result of construction, or in soils deprived of humus for one reason or another. The experience of gardeners in the USA, where there are several commercial companies producing mycorrhiza for gardeners, says that in extreme conditions, adding mycorrhizal preparations to the soil has a very good effect. Gardeners who have received land deprived of fertility for use or are located in areas with an unfavorable climate have learned from their own experience that inoculation with mycorrhiza gives them the opportunity to have a flowering garden even in these unfavorable conditions. Usually the mycorrhiza preparation is in the form of a powder containing spores. It is used to treat seeds or roots of seedlings. Endomycorrhiza preparations are used for ornamental and vegetable plants, and ectomycorrhiza preparations are used for trees and shrubs. However, to get a good effect from mycorrhiza, you need to do important condition– switch to an organic gardening method. This means using organic fertilizers, not digging up the soil (only loosening), mulching, and refusing to use high doses mineral fertilizers and fungicides.
The role of mycorrhiza in plant life.
The symbiosis of plants and fungi has existed for 400 million years and contributes to the great diversity of life forms on Earth. In 1845 it was discovered by German scientists. Mycorrhizal endofunges penetrate directly into the root of the plant and form a “mycelium” (mycelium), which helps the roots strengthen the immune system, fight pathogens of various diseases, and absorb water, phosphorus and nutrients from the soil. With the help of a fungus, the plant uses soil resources to full power. One root could not cope with such a task; Without the support of fungi, plants have to direct additional reserves to increase the root system, instead of increasing the above-ground part. Mycorrhiza improves soil quality, aeration, porosity, and the volume of the total absorbent surface of the plant root increases a thousand times! Due to active human intervention in natural processes: the use of heavy equipment, the introduction of chemical fertilizers, construction work, laying pipelines, asphalt and concrete, air and water pollution, dam construction, soil cultivation, soil erosion, etc. - plants began to be exposed to unprecedented stress, their immunity weakened and led to death.
The German company Mykoplant AG - a leading global manufacturer - sells the endofunge Mykoplant ® BT - an innovative product, an environmentally friendly natural product, an organic plant growth regulator, approved by the Ministry of Agriculture of the Federal Republic of Germany. Mikoplant AG is the only company in the world that produces granular mycorrhizal preparations. Mykoplant ® BT is the spores of the endomycorrhizal fungus (Glomus family), enclosed in 3-5 mm of clay (carrier). It took decades of painstaking research to determine the improving qualities of mycorrhizal fungi. The granulated form of the drug is protected by an international patent. The drug is grown in greenhouses.
Mykoplant ® BT promotes the formation of mycorrhiza in 90% of plants and trees.
Does not have phytopathogens and pathogenic microorganisms.
Not an ounce of chemicals.
No negative impact on people, animals or the environment.
Non-toxic, does not accumulate in plants.
Positive effects of mycorrhiza:
Saves water up to 50%
Stores nutrients for plants
Increases growth and improves plant quality
Increases resistance to drought, lack of drainage
Increases resistance to salts and heavy metals
Improves appearance, taste and aroma
Improves stress resistance and overall plant immunity
Improves disease tolerance
Reduces infection in roots and foliage
Accelerates the establishment of plants in a new place
Increases productivity, growth of green mass
Accelerates root development and flowering by 3-4 weeks
Works well in salty or waste-contaminated soil
Use once with perennial plants
What does a mushroom do? 1. Stores additional water (saving up to 50% depending on region) and nutrients for the plant. 2. Dissolves and supplies the plant with unavailable mineral nutrients, such as phosphates. 3. Protects the plant against underground pests (for example, nematodes).
What does the plant do? Supplies the fungus with carbohydrates (glucose)
To facilitate penetration into the root, the product must have direct contact with it. Used especially effectively in spring, early stages plant development, but is successfully used at any stage of plant development. The activity of mycorrhiza is determined by the number of spores per cm3 of the product (in the USA only 10 spores per cm3 are produced and the price of one liter of the product in the USA is $120). Is the number of spores in a product important? Yes, the number of spores is important, since it determines the efficiency of colony formation and the level of bioactivity.
Mycorrhizal fungi are already in the soil. Why then inoculate crops with the drug? Although mycorrhizal fungi can theoretically be found in the soil, not all types are best suited for your crop. The mycoplant consists of many Glomus families, so successful colonization can be considered almost guaranteed. In which countries is the drug already used? Germany, Bahrain, Qatar, Kuwait, Greece, United Arab Emirates, Turkey, Egypt, Holland.
What is the unit of measurement for the drug? It is customary to measure in liters, which is equal to approx. 0.33 kg
Who else in the world produces mycorrhizal preparations in granular form? Nobody; Mikoplant AG is the only company in the world that has succeeded in this.
How many years has the company been in existence? The company was registered in 2000.
Is there an ISO certificate for the drug? Currently no, because the quality of the drug is checked by the ISO-certified German Institute for Innovation Technology ITA.
Are all aspects of the influence of mycorrhiza on a plant known? There is still a long way to go. Scientists continue to study the unique natural mechanism of interaction between the drug and the plant, and we can only guess about all the positive aspects of the symbiosis.
Unlike chemicals, the drug cannot be overdosed. Without loosening the soil, when adding the drug to the soil for perennial plants It is applied only once, then the mushroom reproduces underground on its own. The technology for using the drug is carried out with the participation of German specialists. Before applying the granulate, the soil is analyzed and the crops to be planted are calculated. In each case, a suitable substrate and host plant are required; it is important to conduct a variety of experiments during the cultivation period in different climatic zones. Burnt clay is used as a spore carrier.
Advantages of granulate:
1. Long shelf life
2. Light weight (350 kg/m3)
3. Convenient transportation
4. Convenient to use
5. Can be selectively disinfected
6. You can change the number of spores depending on the colonies
7. You can easily dose the drug
8. Can be applied using technical means
Methods of application:
1. Apply the granulate closer to the root into a hole in the pot or directly into the soil.
2. Mechanized application into previously plowed soil.
3. Mixing granulate with grain/seeds before sowing.
Application technology:
The use of the drug does not require special equipment. It is important to ensure contact between the fungus and the roots. Drill holes in the tops of an imaginary five-pointed star at a distance of 1-1.5 meters from the tree trunk (diameter = 5-10 cm, depth 30-50 cm), add 100-200g of granules to each hole, cover with soil, water. Results appear after 5-6 weeks. 1 liter of the drug corresponds to 300-330 grams of product.
One-time use depends on the volume of the root:
1. Seedlings 10 - 25 ml/plant
2. Young bushes 25 - 100 ml/bush
3. Young trees 100 - 250 ml/tree
In order to more clearly imagine what mycorrhiza of tree roots looks like externally, it is necessary to compare the appearance of root endings with mycorrhiza with the appearance of roots without it. The roots of Euonymus warty, for example, devoid of mycorrhiza, are sparsely branched and are the same throughout, in contrast to the roots of species that form mycorrhiza, in which the sucking mycorrhizal endings differ from the growth endings that are not mycorrhizal. Mycorrhizal sucking endings either swell club-shaped at the tip in oak, or form very characteristic “forks” and complex complexes of them, reminiscent of 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 influence of the fungus. By making a thin section through the mycorrhizal end of the root, you can be convinced that the anatomical picture can be even more diverse, i.e. the cover of fungal hyphae entwining the root ending can be of different thickness and color, be smooth or fluffy, consisting of so dense intertwined hyphae, which gives the impression of real tissue or, conversely, to be loose.
It happens that the cover consists not of one layer, but of two, differing in color or structure. The so-called Hartig network can also be expressed to varying degrees, i.e. hyphae running along the intercellular spaces and collectively forming something like a network. IN different cases 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 bark parenchyma, which is especially pronounced in the case of mycorrhiza of aspen and birch, and are partially digested there. But no matter how peculiar the picture is internal structure mycorrhizal roots, in all cases it is clear that the fungal hyphae do not penetrate at all into the central cylinder of the root and into the meristem, i.e., into the zone of the root end where root growth occurs due to increased cell division. All such mycorrhizae are called ectoendotrophic, since they have both a surface sheath with hyphae extending from it, and hyphae extending inside the root tissue.
Not all tree species have the types of mycorrhiza described above. In maple, for example, the mycorrhiza is different, that is, the fungus does not form an outer sheath, but in the parenchyma cells you can see not individual hyphae, but entire balls of hyphae, often filling the entire space of the cell. This 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 type of tree, and the structure and surface of the sheath depend on the type of fungus that forms the mycorrhiza, and, as it turned out, mycorrhiza can be formed simultaneously by not one, but two fungi.
What mushrooms form mycorrhiza and with what species? Resolving this issue was not easy. IN different time were proposed for this different methods, up to carefully tracing the course of fungal hyphae in the soil from the base of the fruiting body to the root end. The most effective method It turned out that a certain type of fungus was sown under sterile conditions in the soil on which a seedling of a certain tree species was grown, i.e., 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 pine seedling was grown sterilely and a fungus was introduced in the form of mycelium taken from a young fruiting body at the transition of the cap to the stem, and in the other there was liquid for the necessary soil moisture. Subsequently, scientists who continued 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.
Using the Melin method, by 1953 the connection between tree species and 47 species of fungi from 12 genera had been experimentally proven. It is now known that mycorrhizae with tree species can form more than 600 species of fungi from such genera as fly agarics, rowers, hygrophores, some laticifers (for example, milk mushrooms), russula, etc., and it turned out that everyone can form mycorrhiza not with one, but with different tree species. In this regard, all records were broken by a marsupial fungus that has sclerotia, Caenococcum granuformis, which under experimental conditions formed mycorrhiza with 55 species of tree species. The sublarch butterfly is characterized by the greatest specialization, forming mycorrhiza with larch and cedar pine.
Some genera of fungi are not capable of forming mycorrhizae - talkers, colibia, omphalia, etc.
And yet, despite such wide specialization, the impact of different mycorrhizal fungi on higher plants is not the same. Thus, in the mycorrhiza of Scots pine formed by the oiler, the absorption of phosphorus from hard-to-reach compounds occurs better than when the fly agaric is involved in the formation of mycorrhiza. There are other facts that confirm this. This is very important to take into account in practice, and when using mycorrhization of tree species for their better development, one should select a mushroom for a particular species that would have the most beneficial effect on it.
It has now been established that mycorrhizal hymenomycetes do not form fruiting bodies in 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, saffron milk mushrooms, porcini mushrooms, aspen mushrooms and other valuable types of edible mushrooms in the beds. However, in principle this is possible. Someday, even in the near future, people will learn to give the mycelium everything that it receives from cohabitation with the roots of trees, and will force it to bear fruit. In any case, such experiments are being conducted in laboratory conditions.
As for tree species, spruce, pine, larch, fir, and perhaps most other conifers are considered highly mycotrophic, and hardwood- oak, beech and hornbeam. Birch, elm, hazel, aspen, poplar, linden, willow, alder, rowan, and 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 fast-growing species such as poplar and eucalyptus, the absence of mycorrhiza is often associated with their rapid consumption of the resulting carbohydrates during intensive growth, i.e., carbohydrates do not have time to accumulate in the roots, which is a necessary condition for a fungus to settle on them and mycorrhiza to form.
What are the relationships between the components in mycorrhiza? One of the first hypotheses about the essence 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 fungal mycelium in humus soils, where there are usually a lot of mushrooms. Those plants that had a powerful root system and good transpiration did not suffer much in the conditions of such competition, but those whose root system was relatively weak and transpiration was reduced, i.e. plants that were not able to successfully absorb soil solutions, withdrew difficult situation, forming mycorrhiza with a powerfully developed system of hyphae that penetrate the soil and increase the absorptive capacity of the root. The weakest point of this hypothesis is that there is no direct relationship between the absorption of water and the absorption of mineral salts. Thus, plants that quickly absorb and quickly evaporate water 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 lignin-protein complexes of the soil, destroy them and make them available to higher plants. Suggestions were also made, which were later confirmed, that the fungus and plant can exchange growth substances and vitamins. Fungi, as heterotrophic organisms that require ready-made organic matter, primarily receive carbohydrates from higher plants. This was confirmed not only by experiments, but also by direct observations. For example, if trees grow in a forest in heavily shaded areas, the degree of mycorrhiza formation is greatly reduced, since carbohydrates do not have time to accumulate in the required quantities in the roots. 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.
From the definition of the term mycorrhiza given at the beginning of the section, it follows that this is a symbiosis of fungi with the roots of higher plants.
In this regard, symbiotrophic fungi involved in the formation of mycorrhizae are called mycorrhizal fungi, or mycorrhiza-formers. Isolated from mycorrhizas into culture, these fungi (Shemakhanova, 1962) do not form any reproductive organs by which their systematic position could be directly determined. Therefore, to determine mycorrhizal fungi and their connection with a particular tree species or other plant, they were used at different times. various methods.
The simplest method of direct observation in nature is based on the external connection that exists between mycorrhiza and ground, mainly cap mushrooms. The connections between mushrooms and plants have been noted for a long time, and on this basis the names of mushrooms are given according to the tree in the forest under which they grow, for example: boletus, or birch berry, - under a birch; boletus, or aspen, - under the aspen. The close connection between fungi and plants is evidenced by the spider web mushroom (Cortinarius hemitridus), which, in the apt expression of E. Melin, an outstanding researcher of mycorrhizae of tree species, follows the birch like “a dolphin follows a ship.” Observations in nature served as starting points for subsequent research and have not lost their importance to this day as an auxiliary method.
Mycorrhiza-forming fungi are determined by the hyphae of fungi, both growing in natural conditions and grown in pure culture, by the serological method, the method of semi-sterile and sterile cultures. In the process of application, the methods were modified and improved. For example, to determine the types of mycorrhiza-formers, a method for identifying mycorrhizal mycelium with soil mycelium of fungi considered mycorrhiza-forming was proposed (Vanin and Akhremovich, 1952). The most accurate and reliable method for resolving the question of the actual participation of certain fungi in the formation of mycorrhizae is the method of pure cultures of fungi and the method of sterile cultures of mycorrhizae.
Using various research methods and especially the pure culture method, scientists have determined the composition of mycorrhiza-forming fungi for many tree species: pine, spruce, larch, oak, birch and other coniferous and deciduous species.
Many scientists in our country and abroad have compiled lists of mycorrhizal fungi of various forest tree species. At the same time, different authors cite either a larger or smaller number of fungi that take part in the formation of mycorrhizae of one or another species.
With regard to the systematic composition of fungi involved in the formation of ectotrophic mycorrhizae, all researchers believe that mycorrhizal fungi belong predominantly to the orders of Aphyllophorales and Agaricales of the class of basidiomycetes. In this case, the most frequently named genera of fungi that form ectotrophic mycorrhiza of tree species are: Amanita, Boletus, Cantharellus, Hebe-loma, Lactarius, Tricholoma, etc. Representatives of the order Gasteromycetes (Gasteromycetales) from basidiomycetes, for example, Geaster, Rhisopogon, take part in the formation of mycorrhizae ; from the class of marsupial fungi (Ascomycetes), for example, Gyromitra, Tuber; from imperfect fungi (Fungi inperfecti), for example Phoma, as well as from other systematic categories.
The composition of mycorrhiza-forming fungi and their association with some of the main tree species growing on the territory of the Soviet Union is not indicated full list, compiled primarily from published materials.
The given list of fungi that form ectotrophic mycorrhiza with the roots of some tree species indicates that their number different breeds various. There are 47 species of mycorrhiza-forming fungi in pine, 39 in oak, 27 in fir, 26 in birch and 21 in spruce. At the same time, mycorrhizal fungi include fungi from both the group of orders Hymenomycetes and Gasteromycetes of the Basidiamycetes class, and from the class of marsupial fungi. Other tree species have fewer mycorrhizal fungi, for example, larch has only 15 species, aspen has 6 species, and linden has even fewer - 4 species.
In addition to the quantitative composition by species and belonging to certain systematic categories, mycorrhizal fungi differ in biological features. Thus, mycorrhizal fungi differ in the degree to which they are confined in their development to the roots of certain plants and in their specialization.
Most fungi involved in ectotrophic mycorrhiza are not specialized on one particular host plant, but form mycorrhiza with many types of tree species. For example, the red fly agaric (Amanita muscaria Quel.) is capable of forming mycorrhizae with many coniferous and deciduous tree species. Some species of Boletus, Lactarius, Russula are poorly specialized, the fruiting bodies of which are often found in combination with certain species forest trees. For example, late butterberry (Boletus luteus L.-Ixocomus) grows in pine and spruce forests and is associated with the formation of mycorrhiza on pine: birch grass (Boletus scaber Bull. var. scaber Vassilkov-Krombholzia) forms mycorrhiza mainly on birch roots.
The least specialized among all the mycorrhiza-formers of forest trees is the indiscriminate Cenoccocum graniforme. This fungus was found in the root system of pine, spruce, larch, oak, beech, birch, linden and 16 other woody plants (J. Harley, 1963). The lack of specialization and promiscuity in relation to the substrate of the coenococcus is indicated by its wide distribution even in soils on which none of the known hosts of the fungus grow. Other non-specialized fungi, for example, boletus bovinus L.-Ixocomus and common birch (Boletus scaber Bull. var. scaber Vassilkov-Kroincholzia) can be found in the soil in the form of mycelial strands or rhizomorphs.
The low specialization of mycorrhizal fungi is also manifested in the fact that sometimes several mycorrhizal fungi form ectotrophic mycorrhiza on the roots of the same tree species in natural forest conditions. Such ectotrophic mycorrhiza of the root of one tree or a branch of the root, formed by various symbiont fungi, is called by some scientists multiple infection (Levison, 1963). Just as most mycorrhizal fungi do not have strict specialization with respect to plant species, host plants do not have specialization with respect to fungi. Most species of host plants can form mycorrhizae with several species of fungi, i.e., the same tree can simultaneously be a symbiont of several species of fungi.
Thus, the composition of fungi that form ectotrophic mycorrhiza is diverse in terms of systematic characteristics and biological characteristics. Most of them belong to slightly specialized illegible forms that form mycorrhizae with coniferous and deciduous tree species and are found in the soil in the form of mycelial strands and rhizomorphs. Only some mycorrhizal fungi have a narrower specialization limited to one plant genus.
The composition of fungi that form endotrophic mycorrhiza is no less diverse. Endotrophic mycorrhizal fungi belong to different systematic categories. Here, first of all, a distinction is made between endotrophic mycorrhiza, formed by lower fungi, in which the mycelium is noncellular, nonseptate, and higher fungi with multicellular, septate mycelium. Endotrophic mycorrhiza, formed by mushrooms with nonseptate mycelium, is sometimes called phycomycete mycorrhiza, since nonseptate mycelium is found in lower fungi of the class Phycomycetes. The mycelium of phycomycete mycorrhiza is characterized by a large diameter of hyphae, its endophytic distribution in the tissues of the plant root and the formation of arbuscules and vesicles inside the tissues. For this reason, endotrophic mycorrhiza is sometimes also called vesicular-arbuscular mycorrhiza.
The group of fungi Rhizophagus, consisting of two phycomycetes Endogone and Pythium, which are very different from each other in cultural and other characteristics, takes part in the formation of phycomycete endotrophic mycorrhiza.
The composition of endophytic mycorrhiza fungi with septate mycelium varies depending on the type of mycorrhiza and the group of plants from whose roots it is formed. Orchids (Orchidaceae) have long attracted the attention of botanists for their diversity of forms, methods of reproduction and distribution, and economic value. These fungi have also been studied from the point of view of mycorrhiza, since all representatives of this family are susceptible to infection by fungi and contain fungal mycelium in the cells of the cortex of their absorbing organs. Orchid fungi constitute a separate group in many respects: they have septate mycelium with buckles, and according to this feature they are classified as basidiomycetes. But since they do not form fruiting bodies in culture, they are classified as imperfect stages, the genus Rhizoctonia-Rh. lenuginosa, Rh. repens, etc.
At different times, many species of Rhizoctonia, including perfect stages of basidiomycetes, such as Corticium catoni, were isolated and described from seeds and adult orchid plants. The mycelium of basidiomycetes with buckles, isolated from orchids, is assigned to one or another genus based on its fruiting bodies and other characteristics. For example, Marasmius coniatus forms mycorrhiza with Didymoplexis, and Xeritus javanicus with Gastrodia species. Honey fungus (Armillaria mellea Quel) does not form buckles, but it is easy to identify in its vegetative form by its rhizomorphs. It is a mycorrhiza-former in the galeola vine (Galeola septentrional is), gastrodia (Gastrodia) and other orchids.
Heather fungi (Ericaceae) were originally isolated from the roots of lingonberry (Vaccinium vitis idaea), heather (Erica carnea) and heather (Andromedia polifolia). In culture, these fungi formed pycnidia and were called Phoma radicis with 5 races. Each race was named after the plant from which it was isolated. Subsequently, it was proven that this fungus is a mycorrhiza-former of heathers.
Very little is known about the fungi that form peritrophic mycorrhiza. In all likelihood, this includes some soil fungi that can be found in the rhizosphere of different tree species under different soil conditions.
