Why do trees grow fungi?

It is a fungus (fungus; Fungi) is a kind of heterotrophs with eukaryotes and cell walls. There are many species and genera, with 654.38+100,000 reported genera and 654.38+100,000 species. Except for a few lower types of single cells, most of its vegetative bodies are composed of slender tubular mycelium. The hyphae of lower fungi have no septa, while those of higher fungi have septa. The former is called partition, and the latter is called partition. In the cell walls of most fungi, chitin is the most characteristic, followed by cellulose. Common fungal organelles are mitochondria, microsomes, ribosomes, vacuoles, lysosomes, vesicles, endoplasmic reticulum, microtubules, flagella and so on. Common inclusion bodies are glycogen, crystals, liposomes and so on.

Fungi are usually divided into three categories, namely, yeast, mold and mushroom (large fungi), belonging to different subphylum.

Macrofungi refer to fruiting bodies or sclerotia that can form fleshy or gelatinous substances, most of which belong to Basidiomycotina, and a few belong to Ascomycota. Common macrofungi are Lentinus edodes, Volvariella volvacea, Flammulina velutipes, Agaricus bisporus, Pleurotus ostreatus, Auricularia, Tremella, Dictyophora, Morchella and so on. They are not only important fungi and vegetables, but also important resources for food and pharmaceutical industries.

Edit the plant of this fungus.

The structure of the vegetative growth stage of fungi is called vegetative body. The vegetative bodies of most fungi are branched filaments, and a single filament is called mycelium. Many hyphae are collectively called mycelium. The hyphae growing on the substrate are called hyphae. Microscopically, the mycelium is tubular, with cell walls and cytoplasm, colorless or colored. Mycelium can grow indefinitely, but the diameter is limited, generally 2-30 microns, and the maximum can reach 100 micron. The hyphae of lower fungi are called septate hyphae, and those of higher fungi are called septate hyphae. In addition, the vegetative bodies of a few fungi are not filamentous. But heteroplasmic plasmodium without cell wall or oval single cell with cell wall. Fungi parasitic on plants usually spread from cell to cell in the form of mycelium.

When the mycelium comes into contact with the host cell wall or protoplasm, nutrients enter the mycelium due to osmotic pressure. After some fungi, such as living vegetative organisms, invade the host, hyphae form a special mechanism to absorb nutrients in the host cell, which is called haustorium. The shape of haustorium varies from species to species, for example, the haustorium of powdery mildew is palm-shaped, the mold is filamentous, the rust is finger-shaped, and the white rust is spherical. The mycelium of some fungi grows to a certain stage and can form loose or tight tissues. The tissue of seedling silk mainly includes sclerotia, matrix and rhizome. Sclerotinia sclerotiorum is a dormant body formed by closely intertwined hyphae. The inner layer is sparse and the outer layer is quasi-thin-walled. The epidermal cell wall is thick, dark and hard. The function of sclerotia is mainly to resist adverse environment. However, when the conditions are suitable, sclerotia can germinate to produce new vegetative hyphae or form new propagules from them. The shape and size of sclerotia vary greatly, usually like mung beans, rat droppings or irregular. Matrix is a mat-like structure formed by hyphae interwoven on the surface or under the epidermis of the host, sometimes combined with the host tissue. The main function of the base is to form a mechanism for holding children, but it also has the function of overcoming harsh environment. The funicle is a long rope-like structure composed of parallel mycelium, which is similar in shape to the roots of plants, so it is also called rhizome. The bacteria rope can resist the harsh environment and help bacteria spread on the substrate.

Some cells in hyphae or spores of some fungi swell and become round, protoplasm is concentrated, and cell walls are thickened to form chlamydospores. It can resist adverse environment and germinate into mycelium when conditions are suitable.

Edit the propagule of this fungus.

When the vegetative life lasts for a certain period of time, fungi begin to transfer to the reproductive stage, forming various propagators, namely fruiting bodies. The propagules of fungi include asexual spores formed by asexual reproduction and sexual spores produced by sexual reproduction.

1. Asexual reproduction

Asexual reproduction refers to the reproduction of offspring individuals without nuclear matching and meiosis. Its basic feature is that vegetative propagation usually produces asexual spores directly from mycelium differentiation. There are three common asexual spores:

(1) zoospores: formed in zoospore sacs. The swimming sporangium is formed by the expansion of mycelium or the top of sporangium. Zoospores have no cell wall and have 1-2 flagella, which can swim in water after release.

(2) sporangium spores: formed in sporangium. Sporangium is formed by the swelling of the top of sporangium. Ascomycetes have cell walls and no flagella, and can fly with the wind after being released.

(3) Conidia are produced on the conidiophore formed by mycelium differentiation. They are terminal, lateral or cross-growing, with various shapes and sizes. They are unicellular or multicellular, colorless or colored, and fall off from the robe handle after maturity. Conidia and conidiophore of some fungi are still embedded in conidia. There are two main types of fruit, that is, nearly spherical meristem and cup-shaped or disk-shaped apetalous meristem

2. Sexual reproduction fungi grow and develop to a certain period (usually to the later stage) for sexual reproduction. Sexual reproduction is a way of reproduction in which two sexual cells combine and the nucleus undergoes meiosis to produce robes. Most fungi differentiate from hyphae to produce gametophytes, which are sex organs and form sexual vesicles through the combination of male and female gametophytes. The whole process can be divided into three stages: mass matching, nuclear matching and meiosis. The first stage is mass matching, that is, after the fusion of two sex cells, the cytoplasm and nucleus (N) of the two cells are fused in the same cell to form a binuclear phase (N+N). The second stage is nuclear matching, that is, two haploid nuclei are combined into a diploid nucleus (2N) in the fusion cell. The third stage is meiosis, in which diploid nuclei undergo two successive divisions to form four haploid nuclei (N), thus returning to the initial haploid stage. Fungi can produce four types of sexual spores after sexual reproduction.

Oospore: the sexual spore of oomycete. After the two heterozygotes-male organ and egg storage-contact, the cytoplasm and nucleus of male organ enter the egg storage through the insemination tube, which matches with the nucleus of the egg ball, and finally the fertilized egg ball develops into a thick-walled diploid oospore.

(2) Conjunctive spores: the sexual spores of zygobacteria. It is a thick-walled spore formed by the fusion of two gametophytes into 1 cell in the way of gametophyte combination, and the mass matching and nuclear matching in this cell.

(3) Ascomycetes: the sexual spores of Ascomycetes. Usually, it is a haploid spore formed by the combination of two heterogametes, male organs and ascomycetes through mass matching, nuclear matching and meiosis. Ascomycetes are attached to colorless, transparent, rod-shaped or oval cystic structures, which are called ascomycetes. Usually, 8 ascospores are formed in each ascocyst. Ascomycetes are usually produced in the covered fruit. Ascomycetes are generally divided into four types, namely, spherical closed capsules without holes, bottle-shaped or spherical capsules with true shell walls and fixed holes, sub-chambers without true shell walls and fixed holes due to seat disintegration, and disk-shaped or cup-shaped pistils.

(4) Basidiospores: sexual spores of basidiomycetes. Usually, "+"and "-"hyphae directly combine to form binuclear hyphae, and then the cells at the top of binuclear hyphae expand into rod-shaped burdens. After nuclear pairing and meiosis, four exogenous haploid basidiospores are produced on the basidium.

In addition, some lower fungi, such as Rhizopus, produce sexual spores. And hypha species. It is a thick-walled resting spore, which is formed by the combination of swimming gametes and then developed from fertilized eggs.

Edit the origin and evolution of fungi in this section.

There are two main schools of thought about the origin and evolution of fungi. One school thinks that fungi evolved from algae. Due to the loss of pigment, these algae changed from autotrophic to heterotrophic, and the physiological changes caused morphological changes. Another school thinks that except oomycetes from algae, other fungi come from primitive flagellates.

Fungi is a rich natural resource. People and animals consume a lot of fungi and fruiting bodies every year; Fungi are also important medicinal materials. Some metabolites of fungi are widely used in industry, such as ethanol, citric acid, glycerol, enzyme preparations, sterols, fats, plastics, growth promoters, vitamins and so on. And these things can be produced on a large scale. During the decomposition of fungi, it recovered many important chemical elements. Fungi directly or indirectly affect the material circulation and energy conversion of the earth's biosphere.

There are several kinds of fungi:

mould

Also known as "filamentous bacteria". This is a fungus. The body is filamentous and tufted, and can produce various forms of spores. More rotten. There are many kinds, such as Rhizopus, Mucor, Aspergillus and Penicillium. Mold can be used to produce industrial raw materials (citric acid, methylene succinic acid, etc. ), food processing (brewing soy sauce, etc. ), antibiotics (such as penicillin and griseofulvin) and pesticides (such as "920" and Beauveria bassiana). However, it will also lead to mildew and deterioration of industrial raw materials and products, as well as agricultural and forestry products. Another small number of molds can cause diseases of people, animals and plants, such as tinea capitis, tinea pedis and sweet potato rot.

yeast

This is a fungus. The body is round, oval or ovoid, and there are nuclei, vacuoles and granular substances inside. Usually propagated by budding; Some can be split in half; Some species can produce ascospores. Widely distributed in nature, especially in grapes and other fruits and vegetables. It is an important starter, which can decompose carbohydrates to produce alcohol and carbon dioxide. Bread yeast, feed yeast, alcohol yeast and wine yeast are commonly used in production. Some can synthesize medical cellulose, and some can be used for petroleum fermentation.

brewer's yeast

It belongs to the genus Saccharomyces. Cells are round, oval or oval. Bud grafting can form ascospores. In the fermentation industry, it can be used to produce alcohol or medicinal yeast, and products such as clots, ergosterol, lecithin, coenzyme A and cytochrome C can be extracted through comprehensive utilization of bacteria.

Monascuspurpureus belongs to Ascomycetes, Aspergillus. The mycelium is purplish red. In the process of asexual reproduction, a single or a small cluster of spherical or pear-shaped meristems is formed at the top of the mycelium branches. During sexual reproduction, spherical and orange-red fruit is produced, and an ascospore containing 8 ascospores is endogenous. Monascus can make Monascus, brew red lactobacillus and produce glucoamylase.

mycotoruloides

Yeast that can form pseudohyphae without producing ascospores. Many candida species can use n-alkanes as carbon sources for petroleum fermentation and dewaxing, and produce valuable products. Among them, Candida lipolytica or Candida tropicalis is a Candida species with strong ability to oxidize n-alkanes. Some species can be used as feed yeast; Individual species can cause human or animal diseases.

Candida albicans

Or Candida albicans. An oval candida, which can germinate and reproduce. It usually exists in the mouth, intestines and upper respiratory tract of normal people and can cause oral diseases, such as thrush or other diseases.

Aspergillus flavus

A little knowledge of fungi, Aspergillus flavus common saprophytic fungi. More common in moldy grains, grain products or other moldy organic matter. The colony grows rapidly, with loose structure, yellow-green surface and colorless or slightly brown back. The thallus is composed of many complicated branched hyphae. Vegetative hyphae are separated; Some aerial hyphae form a long and rough conidiophore, and a bottle-shaped or nearly spherical apical sac is produced at the top of the stem. There are many peduncles (usually double-layered) on the surface of the capsule, and spherical conidia with rough surface are formed on the peduncles. Conidiophore, apical sac, peduncle and conidia are in the ear of synthetic spores. It can be used to produce amylase, protease and phosphodiesterase, and it is also a common strain in wine-making industry. In recent years, it has been found that some of these strains can produce aflatoxin, causing cancer in human and livestock liver. As early as the 6th century AD, Qi Shu Yao Min recorded that soy sauce was made from yellow clothes and yellow steamed wheat koji. These two kinds of yellow wheat starter are mainly composed of a large number of spores produced by Aspergillus flavus, protease and amylase.

Geotrichum candidum

This is a fungus. Colony plane diffusion, tissue light and soft, milky white. When the mycelium grows to a certain stage, it will break into cylindrical fruit. The optimum temperature for cell growth is 28℃. Common in milk and various dairy products (such as yogurt and cheese); Geotrichum candidum is usually found in pickles and soy sauce. Can be used for making picric acid and yeast tablets.

Antibiotic bacteria

Also known as "antagonistic (antagonistic) antibacterial". It can inhibit the growth and development of other microorganisms and even kill some microorganisms of other microorganisms. Some of them can produce antibiotics, mainly actinomycetes and some fungi and bacteria. Such as streptomycin produced by Streptomyces, penicillin produced by Penicillium, polymyxin produced by Myxomycetes, etc.

pseudohypha

Some yeasts, such as Candida, germinate and reproduce, and their daughter cells form long chains and have branches, which are called pseudohyphae. The intercellular junction is narrow, such as lotus root node, and there is generally no diaphragm.

antibiotic

Also known as "antibiotics". Mainly refers to the chemical substances produced by microorganisms that can inhibit or kill other microorganisms, such as penicillin, streptomycin, chlortetracycline, kasugamycin, gentamicin and so on. Antibiotics can also be extracted from some higher plants and animal tissues. Some antibiotics, such as chloramphenicol and cycloserine, are mainly produced by chemical synthesis at present. By changing the chemical structure of antibiotics, new antibiotics with better performance can be obtained, such as semi-synthetic neopenicillin. In medicine, antibiotics are widely used to treat many microbial infectious diseases and some cancers. In animal husbandry and veterinary medicine, it is not only used to prevent some infectious diseases, but also used for some antibiotics to promote the growth of poultry and livestock. In agriculture and forestry, it can be used to control microbial diseases of plants. In the food industry, it can be used as a preservative for some foods.

Pathogenic bacteria

Fungi (fungi) are eukaryotic microorganisms, which belong to phycomycetes in biological classification. They are widely distributed in nature, and most of them are beneficial to people, such as wine making, sauce making, fermented feed, fattening farmland, making antibiotics, planting mushrooms, food processing and providing Chinese herbal medicine sources (such as Ganoderma lucidum, Poria cocos and Cordyceps sinensis). ), which are all products of fungi, are prepared by themselves or by fungi. Fungi that cause diseases to human beings can be divided into superficial fungi and deep fungi. The former is chronic and difficult to treat, but it has little effect on the body. The latter can invade the internal organs of the whole body and cause death in severe cases. In addition, some fungi are parasitic in grain, feed and food, which will produce toxins and cause toxic mycosis.

Common fungal media are:

Sabouraud medium's formula

Peptone 10g agar 20g

Maltose 40g water 1000ml.

Firstly, add water to peptone and agar, then heat and stir constantly. After the agar is dissolved, 40g of maltose (or glucose) is added, stirred and dissolved, and then packaged and sterilized for later use.

This culture strain is usually used to cultivate a variety of fungi.

Potato sugar agar medium of formula II

Wash and peel potatoes, cut 200 grams into small pieces, add 1000 ml of water, and cook for half an hour to make up the water. Add 10g agar to the filtrate, boil and dissolve, then add 20g sugar (sucrose for mold culture and glucose for yeast culture), replenish water, and package and sterilize for later use.

Adjust the pH value of this culture medium to 7.2 ~ 7.4, and the sugar in the formula, such as glucose, can also be used to cultivate actinomycetes and Bacillus.

Formula bean sprout juice medium

Soybean sprouts 100g agar 15g.

Glucose 20g, water 1000ml.

Wash soybean sprouts and add water to boil for 30 minutes. Filtering with gauze, adding agar into the filtrate, heating to dissolve, adding sugar, stirring to dissolve, adding water to 1000 ml, subpackaging, and sterilizing.

Adjusting the pH value of this culture medium to 7.2 ~ 7.4 can be used to cultivate bacteria and actinomycetes.

Formula four pea agar medium

Pea 80 agar 5g

Water 200 ml

Add water to 80 dried peas, boil for 65438 0 hours, filter with gauze, add agar to the filtrate, boil until dissolved, package and sterilize for later use.

Edit this paragraph of fungi and life

Environmental recovery

Fungi, like bacteria and microorganisms, are decomposers, that is, some organisms that decompose dead organisms. Fungi decompose organisms into various inorganic substances, thus enhancing the fertility of the land.

Food and fungi

Some fungi have also become important food sources. There are more than 200 kinds of edible fungi, such as mushrooms, straw mushrooms, auricularia auricula and tremella aurantialba. And the shells of organisms (animals) invaded by fungi, such as Cordyceps sinensis.

There are also fungi used for food processing, such as yeast used for bread processing, and fungi are also needed for wine making.

Pathogenic bacteria

Fungi have a harmful side in agriculture, forestry and animal husbandry. Fungi can cause a variety of plant diseases and cause huge economic losses. For example, in 1845, 5/6 of potatoes were destroyed in Europe due to the epidemic of potato late blight, and in China, due to 1950 wheat rust and 1974 rice blast, the output of wheat and rice decreased by 6 billion kilograms each.

Fungi can also cause many diseases of animals, plants and humans. There are three main types of human beings: ① fungal infection; 2. Allergic diseases; ③ Toxic diseases.

Resistant fungi

Alexander fleming was lucky to find penicillin. Once he went on holiday and forgot that bacteria were growing in the Petri dish in the laboratory. When he returned to the laboratory three weeks later, he noticed a mold spot growing in the Petri dish. All the bacteria around the mold spot are dead.

What powerful substance does the mold give off? Fleming called it penicillin and found that it could kill many deadly bacteria. However, because penicillin is quickly inactivated after being mixed with serum in a test tube, Fleming believes that it has no effect on humans and animals.

Relationship between fungi and plant roots

The roots of plants are also related to fungi, and the roots with fungi are called mycorrhiza.

Ectomycorrhiza: Fungal hyphae form hyphae on the root surface, winding around the surface of young roots, sometimes invading between cortical cells, but not entering cells. At this time, hyphae replace root hairs and increase the absorption area of roots, such as pine trees;

Endophytic mycorrhiza: hyphae invade epidermal and cortical cells through cell walls, strengthen absorption function and promote the transportation of root substances, such as citrus and walnut;

Endophytic mycorrhiza: There are also hyphae not only wrapped on the surface of young roots, but also infiltrated into cells, which are called endophytic mycorrhiza, such as apples and willows.

Mycelium absorbs water, inorganic salts, etc. For plants, plant hormones and vitamin B are produced at the same time to promote the growth of roots; Plants provide organic nutrients for fungi, such as sugar and amino acids.

More than 2000 kinds of higher plants can form mycorrhiza, such as Platycladus orientalis, Populus tomentosa, Ginkgo biloba, wheat, onion and so on.

Plants with mycorrhiza can't grow normally without fungi, so it is necessary to inoculate and infect the required fungi in advance to facilitate the successful afforestation on the wasteland.