Phylum Fungus
First, the economic use of fungi
1. Food There are more than 800 kinds of fungi that can be eaten in China, many of which are delicious, nutritious, and personally hypertrophied, such as mushrooms, shiitake mushrooms, mouth mushrooms, lion's mane mushrooms, fungus, silver fungus, etc.
2. Medicine There are more than 100 kinds of fungi with anti-cancer effects, and there are many fungi that can be used medicinally, such as poria, Ganoderma lucidum, bamboo yellow and so on.
3. Industrial aspects use yeast, aspergillus, mucorus and other fungi for winemaking, the effect is good; Fungi are also used in chemicals, paper, leather, etc.; Yeast decomposes paraffin in petroleum and reduces the freezing point of petroleum; People also use fungi to extract growth hormone to stimulate crop growth.
4. Fungus in decaying trees and dead branches and leaves can decompose lignin and cellulose, purify the environment, and are more useful than bacteria in promoting material circulation.
Sometimes fungi are harmful to humans, such as causing food mold, human skin diseases, etc., aflatoxin causes human liver cancer, poisonous mushrooms cause death, etc. It is not uncommon.
Second, the main characteristics of fungi
1. Vegetative body A few of the vegetative bodies of fungi are single cells, most of them are branched filamentous bodies, each called hyphae together is called mycelium, hyphae are tubular bodies, with separation or no septum, lower fungi without septum, there are multiple nuclei, higher fungi have transverse septum, there are 1-2 nuclei; In the life history of the fungus, the hyphae will be interwoven into some tissues, which is the trophic structure or reproductive structure of the fungus, common rhizome, substellation, sclerotia, collectively known as mycelial tissue body, their main role is to complete the transition from the trophic to the reproductive stage, dormant in the harsh environment and then wait for the environment to improve after germination into hyphae or fungal entities.
2. Nutritional mode Fungus heterotrophic way of life, some fungal hyphae evolved into a variety of absorbed organs, residing on the living animal and plant bodies directly rely on the high osmotic pressure of mycelial cells to absorb nutrients from the host; Some fungi can secrete decomposition enzymes, which can decompose animal and plant corpses to absorb nutrients; Rhizobia are fungi that live in symbiosis with plants.
3. Fungal cells Most fungal cells have a cell wall composed of chitin, a formed nucleus, a large number of organelles in the cytoplasm, and a large amount of sugar, oil, and protein stored in the cytoplasm; A small number of cells also have various pigments.
4. Reproductive mode Fungi reproduce through vegetative reproduction, asexual reproduction, sexual reproduction, etc.
Vegetative propagation is that some single-celled fungi reproduce through cell division, and some fungal hyphae produce arthrospores or spores to reproduce. Asexual reproduction is when fungi reproduce by producing a large number of asexual spores; Lower and middle fungi in sexual reproduction can combine into zygotes through gametes, or produce sperm and eggs and then cooperate to form oospores.
Third, the main taxa of fungi
The taxa of fungi include more than 10,000 genera and more than 120,000 species, and according to the classification of Ainzworth, the fungal phylum is divided into five subphyla: flagella, zygomycetes, ascomycetes, basidiomycetes, and hemizys. The first two subphylum fungi are lower fungi with no transverse septum in hyphae, the middle two subphylum are higher fungi with transverse septum, and the last subphylum is also higher fungi, but it has not been found to have a sexual stage.
1. Subphylum Dinoflagella Except for a few single-celled fungi, most of the fungi are branched filamentous bodies, and there is no interval between cells during the vegetative period, only in the reproductive period, and swimming spores with flagella are produced during asexual reproduction, which is a typical feature of this subphylum; Oospores and dormant spores are produced during sexual reproduction. For example, water mold is a typical representative of Benyaphylum, which lives on fish gills, broken fish skin, and dead tadpoles, which is very harmful to fish.
2. Zygotic subphylum The fungi of this subphylum are mycelium formed by septate multinucleated cells, which produce static sporangia during asexual reproduction, and gametes form zygotes when sexual reproduction, and this subphylum is a group of fungi that transition from aquatic to terrestrial. Typical representatives are creeping rhizopus, also known as Rhizopus niger or bread mold, which occurs on starchy foods such as bread and steamed buns, causing mildew in food.
3. Ascomycetes subphylum There are many types of fungi in this subphylum, except for yeast that is single-celled, all others are multicellular, these cells have mononuclear or multinucleated, multicellular species are hyphae and have transverse septal walls; During asexual reproduction, single-celled yeasts germinate and multiply, and multicellular spore propagation; During sexual reproduction, ascomycetes are produced, and zygotes meiosis within the ascospores produce ascospores, which are located in the entity of the fungus, and the solid morphology is the basis for further classification of this subphylum. Typical representatives of this subphylum are yeast and gibberella, yeast is unicellular lower ascomycetes, and gibberella parasitizes on wheat, barley, oats and other grasses, which is very harmful to crops.
4. Basidiomycetes subphylum Benya is a higher terrestrial fungus, with saprophytic and parasitic, edible and poisonous, and is closely related to humans; They are multicellular organisms, the hyphae have transverse septa, and the hyphae are divided into primary, secondary and tertiary mycelium; Asexual reproduction of basidiomycetes is accomplished by producing arthrospores, spores, conidia, etc., and sexual reproduction is accomplished through basidiospores through body matching. The entity of basidiomycetes is called basidiocarp, which has various forms such as umbrella and star-shaped. A typical representative is that maize powdery mildew caused corn to suffer from powdery mildew; Black fungus, shiitake mushrooms, and lion's mane mushrooms are delicious fungal ingredients; Ganoderma lucidum is a precious medicinal herb.
5. Subphylum Hemimycetes This subphylum is also called incomplete bacteria, mostly developed septic hyphae, which is haploid; They can only reproduce asexually in the form of buns, and sexual reproduction has not been found. There are more than 1,800 genera and more than 26,000 species of semi-known fungi, of which 300 genera are very harmful pathogens to crops and forests. For example, the rice blast fungus, which is common in rice fields, is the fungus that harms rice the most seriously, which may lead to the failure of rice grains.
Fourth, the origin of the phylum of fungi and the kinship of the subphyla
Fungi are part of the fungus kingdom, and the fungal kingdom shares a common primitive ancestor with animals and plants, but the evolutionary direction is different. The flagella subphylum produces swimming spores, aquatic, zygomycetes similar to its hyphae, only static spores, which are characteristic of binding reproduction and a sign of aquatic to terrestrial transition; The ascomycete subphylum has cysts and zygotic processes, which are more suitable for terrestrial and may have evolved from zygobacteria; The ascomycetes subphylum is terrestrial and the secondary hyphae are binucleated, and basidiomycetes are thought to have evolved from ascomycetes.
