Asexual reproduction of fungi. Mushroom propagation. Mushroom propagation methods

In fungi, vegetative reproduction can be carried out by body parts or spores. Its most primitive form is reproduction by particles of hyphae, as well as sclerotia, fragments of cords and rhizomorphs. Separating from the mother mycelium and entering a favorable environment, they give rise to a new organism.

One of the forms of vegetative propagation is the formation of chlamydospores and oidia. Chlamydospores appear when the contents of certain mycelial cells become compacted and isolated. At the same time, they are covered with a dark-colored dense shell. Chlamydospores can persist for a long time in unfavorable conditions after separation from the mother hyphae cells. When they germinate, they form mycelium or sporulation organs.

Oidia appear after the hyphae disintegrate into individual segments; they are short-lived and equipped with a thin shell. Subsequently, they give rise to a new mycelium. One of their varieties is gemma with a denser dark shell that can be preserved in winter.

Some fungi reproduce by cell budding, a process characteristic of yeast fungi. At first they develop small outgrowths, gradually they increase in size and separate from the mother cell, after which they begin to bud. These cells are blastospores.

Reproductive propagation of fungi

Reproductive reproduction occurs with the help of spores; they can form on the surface of special organs or inside them. In their structure, spores differ from vegetative hyphae. Asexual reproductive reproduction occurs with the formation of spores without fertilization; in sexual reproduction, the appearance of spores is preceded by the sexual process.

Most often, asexual reproduction begins on a well-developed mycelium with a sufficient amount of nutrients. In this process, the spore-bearing organs are sections of hyphae or their special branches. The formation of zoosporangia is the most simple form asexual reproduction. Zoospores retain their viability only in water; they have one or two flagella with which they can move.

The sexual process of fungi is very diverse; in its simplest form, it is the fusion of two identical-shaped, heterosexual zoospores. Zygogamy and oogamy - more complex processes. In the first case, the contents of two outwardly identical germ cells of different sex mycelia are combined; with oogamy, germ cells of different structures are laid on the mycelium - oogonium (female) and antheridium (male). When their contents fuse, an oospore is formed.

Mushrooms reproduce using spores, as well as particles of mycelium, sclerotia and other elements. Any structure that can cause the development of young mycelium is called a diaspora, or propagule. Taking into account their origin, diaspores are divided into specialized, that is, those formed specifically for reproduction (spores), and non-specialized (in particular, pieces of mycelium).

Reproduction by unspecialized diaspores is called vegetative due to the fact that it is carried out using parts or elements of the vegetative bodies of fungi. Regarding filamentous fungi, it should be noted that they reproduce exclusively through pieces of mycelium. This method is used to propagate many types of mushrooms in culture, for example champignons, summer honey fungus, oyster mushrooms, etc.

Reproduction methods

Fungal spores are intended solely for reproduction. In their structure, there are one or more cells that are microscopic in size. Finding yourself in a favorable environment, not large number spores give rise to new mycelium. Most of them die, so all mushrooms form a huge number of spores. Thus, champignons produce approximately 40 million spores per hour, tinder fungus - up to 30 billion.

Taking into account the origin and function of spores in the life of fungi, there are two ways:

1. Spores of sexual reproduction (meiospores).

2. Asexual (mitospores).

With the help of mitospores, fungi spread en masse during the growing season in the absence of recombination of hereditary properties. With the appearance of new mycelia from meiospores, the diversity of fungi increases due to the recombination of characteristics of the parent organisms. In many fungi, both mitospores and meiospores are formed in the life cycle. But in some groups of fungi - deuteromycetes, which unite 30 thousand species, the ability to sexually reproduce is completely reduced. They form only mitospores.

For the formation of mitospores in fungi, special cells (reproductive organ) are used - sporangia, or branches of aerial mycelium. The first spores are called sporangiospores, and the second, formed exogenously, are called conidia.

Sporangiospores can be immobile or have flagella, which gives them the ability to actively move. These are so-called zoospores, which move only in an aquatic environment, and accordingly, reproduction is possible only in the presence of a drop-liquid medium. Reproduction by zoospores is characteristic of all groups of primarily aquatic forms of fungi. In terrestrial species, the ability to produce them has been lost.

In most fungi, asexual reproduction using conidia is widespread. These structures are formed in higher fungi with cellular mycelium on the hyphae of aerial mycelium, most often on special branches - conidiophores. They are small and are formed in huge quantities. The release of conidia is carried out in most cases passively; less often, active discarding is possible, as in nigrospora. During the process of evolution, conidia have acquired multiple adaptations that facilitate their spread.

Meiospores are formed in fungi inside or on the surface of special cells called bursae, asci, or basidia. These are the reproductive organs of fungi. A large group of fungi - ascomycetes, or marsupials - is characterized by the formation of bags with meiospores. Basidia with meiospores are formed in a large group of basidiomycetes, or basidiomycetes (about 30 thousand species). The release of basidiospores or ascospores occurs through their active discarding from the basidium or ascus. When two meiospores merge, a zygote is formed, which, when exposed to favorable conditions, gives rise to a new mycelium

to the word grub, which meant “hump”, “hill”, “hillock”. For comparison, this is also where the name of the hump-nosed breeds of pigeons comes from - “mushroomy”.

In some Russian dialects, all mushrooms are called the word lips, but to a greater extent this applies to popular names some tinder fungi - “lips”, “sponges”. In this form the word passed into some Slavic languages, for example, into Czech ( hoby) and Slovak ( huby). Latin fungus comes from Greek σφογγος , also denoting a sponge, a porous body.

Another interpretation derives the word “mushroom” from the verb “row” (“row”) - when growing, the mushroom is “raked” out of the ground.

A connection with Old Russian is also possible glib- mucus, sticky substance (compare with the Lithuanian word gleivės, having the same meaning). This root passed into the South Slavic languages: Slovenian gliva, Serbian giva. In Ukrainian glyva- name of oyster mushroom.

Systematic position and origin

For a long time, fungi were classified as plants, with which they are similar in their ability to unlimited growth, the presence of a cell wall, adsorptive nutrition, for which they have a very large external surface (rather than phagocytosis and pinocytosis), and the inability to move. But due to the lack of chlorophyll, fungi are deprived of the ability for photosynthesis inherent in plants and have a heterotrophic type of nutrition characteristic of animals, they deposit glycogen, and not starch as a storage substance, the basis of the cell wall is chitin, not cellulose (except for oomycetes), they are used in metabolism urea - all this brings them closer to animals. They are distinguished from both animals and plants by the presence in many groups of a dikaryonic phase and perforations in the intercellular septum.

As a result, fungi have been recognized as a separate independent kingdom, although they have a polyphyletic origin from various flagellated and non-flagellate unicellular organisms. The latter gave rise to zygomycetes, from which higher fungi are derived. Oomycetes may have evolved from heteroflagellate algae. Forms close to modern ones appeared a very long time ago; spores similar to those of Saprolegniaceae are 185 million years old.

Structure

Most fungal cells have a cell wall; only zoospores and vegetative cells of some primitive fungi lack it. 80-90% of it consists of nitrogenous and non-nitrogenous polysaccharides; in most, the main polysaccharide is chitin, in oomycetes it is cellulose. The cell wall also includes proteins, lipids and polyphosphates. Inside there is a protoplast surrounded by a cytoplasmic membrane. The protoplast has a structure typical of eukaryotes. There are storage vacuoles containing volutin, lipids, glycogen, fatty acids (mostly unsaturated) and other substances. One or more nuclei. Different groups have different predominant ploidy stages.

Classification

There is currently no generally accepted classification of fungi, so the information given in the literature or other sources may vary significantly among different authors.

Asco-, basidio- and deuteromycetes are often grouped into the group Higher Fungi ( Dikarya).

Other small groups are also distinguished.

Role in biocenosis

Fungi can live in a variety of environments - soil, forest floor, water, decaying and living organisms. Depending on the method of consumption of organic substances there are:

Meaning for humans

Food use

Edible mushrooms

IN food industry Various microscopic fungi are used: numerous yeast cultures are important for the preparation of vinegar, alcohol and various alcoholic beverages: wine, vodka, beer, koumiss, kefir, yoghurt, as well as in baking. Mold cultures have long been used to make cheeses (Roquefort, Camembert), as well as some wines (sherry).

Due to the high content of chitin in mushrooms, they nutritional value small, and they are difficult to absorb by the body. However nutritional value The benefits of mushrooms lies not so much in their nutritional value, but in their high aromatic and taste qualities, which is why they are used for seasonings, dressings, in dried, salted, pickled form, and also in the form of powders.

Poisonous mushrooms

Mushrooms and preparations made from them are widely used in medicine. For example, in oriental medicine use whole mushrooms - reishi (ganoderma), shiitake, cordyceps, etc. folk medicine Preparations from white fungus, veselka, some tinder fungus and other species are used.

The list of official preparations contains numerous preparations from mushrooms:

• substances extracted from the culture medium of penicillium and other fungi (used in the production of antibiotics).

Use for hallucinogenic purposes

Some types of mushrooms contain psychoactive substances and have a hallucinogenic effect, so ancient peoples used them in various rituals and initiations; in particular, fly agaric mushrooms were used by the shamans of some peoples of Siberia.

Use as pesticides

Preparations based on micromycetes.

Many fungi are capable of interacting with other organisms through their metabolites, or by directly infecting them. The use of agricultural pesticides from some of these fungi is being considered as an opportunity to control pest population sizes agriculture, such as insect pests, nematodes, or other fungi that damage plants. For example, entomopathogenic fungi are used as biopesticides (for example, the drug Boverin from Beauveria bassiana, other drugs from Metarhizium anisopliae, Hirsutella, Paecilomyces fumosoroseus And Verticillium lecanii (=Lecanicillium lecanii). Fly agaric has long been used as an insecticide.

Technical Application

The production of citric acid based on biotechnology - microbiological synthesis - has become widespread.

Damage to the farm

A large number of different pathogenic fungi are known to cause diseases of plants (up to 1/3 of the growing crop and during storage are lost annually due to their fault), animals and humans (dermatoses, diseases of the hair, nails, respiratory and genital tracts, oral cavity). They cause severe food poisoning. Wood-destroying fungi cause rapid destruction of wood materials, buildings and products, and therefore are considered pathogenic in forest phytopathology.

Literature

• "Funghi", - Instituto Geografico De Agostini, Novara, Italy, 1997
• Bondartseva M.A. Key to mushrooms of Russia. Order Aphyllophoraceae. St. Petersburg: Nauka, 1998. Vol. 2
• Garibova L.V., Sidorova I. I. Mushrooms. Encyclopedia of Russian nature. - M.: 1999
• Garibova L.V., Lekomtseva S.N. Fundamentals of mycology (morphology and taxonomy of fungi and fungi-like organisms). M.: KMK, 2007
• Gorlenko M.V. etc. Mushrooms of the USSR. - M.: 1980
• Dyakov Yu., Shnyreva A., Sergeev A. Introduction to fungal genetics. M.: Academy, 2005
• World of plants. in 7 volumes / Ed. A.L. Takhtajyan(chief ed.) and others. T. 2. Mushrooms. / Ed. M.V. Gorlenko. 2nd ed., revised. - M.: Education, 1991. - 475 pp., 24 sheets: ill. - ISBN 5-09-002851-9
• Tobias A. Morphology and reproduction of fungi. M.: Academy, 2006
• Fedorov F.V., Mushrooms. - M., Rosagropromizdat
• Cherepanova N.P. Taxonomy of fungi. - St. Petersburg: SSU Publishing House, 2005

Links

In Russian

• Garibova L.V., Sidorova I.I. Mushrooms. Encyclopedia of Russian nature. - M.: 1999

Fungi are characterized by vegetative, asexual and sexual reproduction. In representatives of teleomorphic fungi, these types of reproduction successively replace each other. During asexual and sexual reproduction, complex morphological structures are formed that differ from each other. Some representatives of the kingdom Fungi in development cycles, two or more different types of spores can be formed, which, as a rule, perform different functions. This phenomenon is called pleomorphism. This is especially true for oomycots, ascomycots and some basidiomycots (rust fungi).

Vegetative propagation. The mycelial hyphae of most types of fungi have a high ability to regenerate, which underlies one of the methods of vegetative propagation of fungi by fragmentation. It is widely used in the national economy for the cultivation of champignons and oyster mushrooms, as well as for obtaining hyphal biomass in the laboratory.

During vegetative propagation, many fungi form specialized structures: 1) oidia; 2) chlamydospores. In addition to reproduction, they also perform the function of tolerating extreme conditions (increasing and decreasing temperature, humidity, etc.); 3) in most yeasts, reproduction occurs by budding.

Asexual reproduction is reproduction through spores: specialized unicellular or multicellular structures resulting from mitosis. Asexual reproduction of fungi is richer in structure and function than vegetative reproduction. Several trends have been observed in the evolution of asexual reproduction. Spores of asexual reproduction can be either mobile (zoospores) or immobile (sporangiospores and conidia, etc.). Motile spores (zoospores) are formed in more primitive fungi, usually living in water (divisions Chytridiomycota, Oomycota etc.). In evolution, the replacement of motile spores by immobile ones is due to the transition of fungi from an aquatic to a terrestrial lifestyle. Examples of transitional forms can be traced to representatives of the order Peronosporales(department Oomycota). In mucor fungi, asexual reproduction is carried out by immobile endogenous spores, huge amount which is formed in a spherical sporangium. However, in many genera of these fungi there is a tendency towards a sharp decrease in the number of spores in the sporangium (sporangioles are formed in the genus Chonaphora– syn. Blakeslea trispora) and subsequently to the replacement of endogenous sporangiospores with exogenous conidia (for example, in species of the genus Thamnidium, department Zygomycota). Due to the fact that in the process of evolution endogenous sporulation is replaced by exogenous one, natural selection initiated the formation of various simple, branching conidiophores and other structures that increase the number of conidia formed. An increase in the diversity of forms of asexual reproduction, leading to a sharp increase in the number of exogenous spores, is accompanied by a loss of the sexual cycle. The predominant part of such fungi belongs to ascomycots, which are characterized by the alternation of many generations of asexual reproduction, which takes on the functions of direct reproduction and dispersal, and one generation of sexual reproduction during the season, ensuring the transfer of extreme conditions and an increase in genetic diversity due to recombination.

However, during the formation of asexual generations, these fungi form so many conidia that the mutation process creates the necessary pool of variability (heterokaryosis, parasexual process), replacing recombination during the process of meiosis, and their wintering is possible in the form of resting vegetative structures (sclerotia, chlamydospores, etc. .). This explains Yu. T. Dyakov (2000) the loss of the sexual stage of the life cycle by many marsupial fungi.

It is with the help of asexual reproduction spores that the vast majority of fungi disperse in natural conditions. In many fungi, for example, ascomycotas, asexual reproduction can be repeated 8–10 times during the growing season. Asexual sporulation (aeciospores, urediniospores, teliospores) are also observed in basidiomycota, but unlike marsupial fungi, in which the conidial stages are haploid, in basidiomycota conidia are usually dikaryotic (urediniospores) and rarely haploid.

Heterothallism and homothallism. Based on gender and sexual compatibility, fungi are divided into two groups: 1) bisexual organisms, in which female and male reproductive structures develop on the same thallus; 2) dioecious, or dimorphic, organisms - male and female reproductive structures develop on different thalli, male and female, respectively. Bisexual organisms of fungi are called homothallic, dioecious ones are called heterothallic. In heterothallic fungi, the sexual cycle can only occur if there are two thalli that are different in gender. Morphologically indistinguishable strains are designated conventionally as “+” and “–”, which indicates a difference in the sexes.

Heterothallism (dioeciousness) in fungi can be of two types: 1) bipolar, when sex is determined by one pair of alleles; 2) tetrapolar, when sex is determined by two pairs of alleles localized on different chromosomes and independently combining.

In bipolar heterothallism, all hyphae grown from spores of one fruiting body are divided into two groups, and when hyphae from these two different groups unite, the sexual process occurs.

In tetrapolar heterothallism, hyphae grown from spores of one fruiting body fall into four sexual groups. In this case, group I merges only with group II and group III - only with group IV. The numerical ratio of these groups for agaricoid fungi (division Basidiomycota), in which tetrapolar heterothallism is very widespread, corresponds to the ratio 1:1:1:1.

Sexual reproduction. Sexual reproduction is called reproduction in which the sexual process takes place, ending with the fusion of the nuclei of specialized cells (gametes, gametangia) or somatic cells. The following types of sexual process are observed in fungi.

1. Gametogamy (planogamy). This is a sexual process in which two gametes (one or both mobile, identical or different sizes) merge. Motile gametes are called planogametes. Gametogamy is divided into isogamy, in which both gametes, mobile and morphologically indistinguishable, merge (copulate), and heterogamy (anisogamy), in which motile gametes differing in size and often in the degree of mobility merge (copulate) (for example, in representatives of the divisions Chytridiomycota).

2. Oogamy, in which reproductive structures are formed - oogonia and antheridium. In the oogonia, a large, immobile egg is formed, and in the antheridium, small, motile sperm are formed, which ultimately penetrate the egg and fertilize it. As a result, a zygote (oospore) is formed. However, in many fungi, during the oogamous sexual process, spermatozoa are not formed in the antheridium (for example, the section Oomycota), and the egg is fertilized by the contents of the multinucleate antheridium, undifferentiated into sperm.

Among the lower fungi there is also gametogamy, called merogamy, in which two specific gametes of much smaller size than vegetative cells merge.

3. Gametangiogamy- a sexual process in which the contents of two specialized reproductive structures - gametangia, not differentiated into gametes, merge. Gametangia are usually multinucleated, and as a result of their fusion, along with the fusion of the cytoplasm, multiple nuclear fusions occur. In zygomycetes, gametangia fuse, in most cases morphologically clearly distinguishable from the hyphae of the mycelium on which they are formed. As a result of fusion, a zygospore is formed, which, after a period of rest, grows into a sporangium.

In ascomycetes, one of the gametangia - the female - is often divided into two parts - askogon And trichogyna. Through the latter, the contents of the male gametangium - the antheridium - enter the ascogon. In this case, only plasmogamy occurs. Male and female nuclei are distributed in pairs along the perimeter of the askogon and form dikaryons. Then the ascogon shell protrudes in different places and forms ascogenous hyphae, on top of which bags are formed.

A detailed description of the completion of the sexual process and the formation of bursae is given in the systematic section.

4. Somatogamy- a process in which reproductive structures are not formed, but ordinary somatic or vegetative cells of mycelial hyphae merge. This type of sexual process is characteristic of some representatives of chytridiomycotes and hyphochytridiomycotes with a unicellular thallus. In this case, two single-celled individuals merge. This type of somatogamy is called hologamia. In basidiomycetes, two vegetative cells of haploid hyphae of the mycelium merge, and, as in ascomycotes, plasmogamy first occurs and dikaryons are formed. In some species of basidiomycetes, fusion of homothallic forms occurs, and since most basidiomycota are heterothallic, the sexual process more often occurs between the latter. Basidiospores can also fuse to form a dikaryotic cell. However, unlike ascomycots (marsupial fungi), basidiomycots have a very long dikaryotic stage. At a certain stage of development, basidia are formed on these dikaryotic hyphae, where the fusion of dikaryon nuclei occurs. A short-lived zygote is formed, the nucleus of which divides meiotically. Basidiospores are formed on the basidium (exogenously), into which the resulting haploid nuclei migrate.

After the dormant period, the zygospore germinates, and all diploid nuclei, except one, die (degenerate). The surviving diploid nucleus divides meiotically, of the 4 resulting haploid nuclei, one germinates and, as a result, a sporangiophorus with a sporangium is formed, in which all sporangiospores are unisexual.

6. Spermatization. Some fungi form small mononuclear structures like conidia on the conidiophore, microconidia capable of copulation, generally called spermatozoa (for example, in many representatives of the departments Ascomycota and less often Basidiomycota). In many ascomycotes, instead of the antheridium, its function is performed by vegetative cells of hyphae, microconidia, conidia or sperm, ascospores, and budding cells. Marsupial fungi are characterized by parthenogamy - self-fertilization inside the ascogon, as well as apomixis.

The main stages of the sexual process in fungi. Fungi, like all eukaryotes, have three cardinal stages of the sexual process.

1. Plasmogamy- fusion of the cytoplasm of two sexually specialized cells, the transition of the nucleus and cytoplasm into the female reproductive structure or even into a somatic cell.

2. Karyogamy– nuclear fusion and, as a result, diploidization. In lower fungi (zygomycetes, endomycetes in marsupial fungi), nuclear fusion occurs immediately after plasmogamy. In higher fungi, this process is delayed and occurs in dikaryotic cells, often after the formation of the corresponding morphological structures - fruiting bodies. Plasmogamy in basidiomycetes occurs shortly after spore germination by primary mycelial hyphae. In the further vegetative phase of the cycle, the mycelial hyphae are dikaryotic.

3. Meiosis(reduction division) typically follows karyogamy. Then one or more mitotic divisions often occur. Ultimately, the number of spores is most often 4 (2) or a multiple of 4: 8 – 32.

Fungi reproduce vegetatively, asexually and sexually. Fungal spores are intended solely for reproduction. However, despite this, each type of fungus lives only in certain conditions and colonizes only a substrate suitable for its development.

It allows you to grow different strains edible mushrooms, differing in yield, quality of fruiting bodies and other economically valuable characteristics.

The oldest heterotrophic organisms are fungi. They occupy a particularly significant place in the entire system of living nature. Mushrooms are our protectors. The mycelium particles carry out the vegetative method of propagation. Special formations on mushrooms take part in this difficult process.

Mushrooms reproduce by budding individual cells or mycelium. A striking example of fungi that reproduce by budding is yeast. The DNA of offspring during vegetative propagation does not differ from the DNA of the parent. There is a lot of literature about which mushrooms reproduce using budding.

This method is when mushrooms reproduce by spores. It is considered to be common to all truffles, molds and other species. Sexual reproduction is when, during the process of fertilization, the DNA of offspring is formed from the DNA of both parents. DNA fusion occurs very differently in the fungal kingdom. Spores consist of one or more cells 3-20 microns in size. Individually, they are not visible to the naked eye.

How do mushrooms reproduce?

In earlier times, pieces of substrate with viable mycelium were selected and transferred to another place where conditions were favorable for the growth and development of mycelium. Mushrooms are studied by the science of mycology, which is considered a branch of botany, since mushrooms were previously classified as part of the plant kingdom.

The biological and ecological diversity of mushrooms is very large. According to modern estimates, there are from 100 to 250 thousand, and according to some estimates, up to 1.5 million species of mushrooms on Earth. The role of mushrooms in nature and in human agriculture can hardly be overestimated. Fungi are present in all biological niches - in water and on land, in soil and on all kinds of other substrates.

Vegetative propagation of mushrooms

In animals and humans, fungi cause skin diseases (dermatomycosis), and sometimes lesions internal organs(deep mycoses). Very dangerous and can be fatal poisoning poisonous mushrooms, as well as mycotoxicosis - poisoning food products, infected with toxins of microscopic fungi.