Fungi are characterized by not originating from the same ancestor, due to this, specialists consider that they are the product of convergent evolution. These are eukaryotic living beings, without chlorophyll, they reproduce by sexual or asexual spores. About 98.000 species of fungi are known so far. Here you will know the Characteristics of Fungi, their types and their way of reproduction.
mushrooms
Fungi are living eukaryotic specimens that are part of the Fungi kingdom, which includes yeasts, molds and mushrooms. In a previous classification, they were placed in the plant kingdom, however, in subsequent studies and descriptions of their particular characteristics that distinguished them, they were placed in a different and specific kingdom, the Fungi kingdom, differentiating them from vegetables.
Fungi do not contain chlorophyll for this reason their brownish white coloration, they have cells with nuclei, they can be unicellular and multicellular organisms. When they are multicellular or multicellular, they are found in nature in their vegetative form, forming hyphae. When these hyphae grow, they form intertwined branches that are called mycelia.
They reproduce by means of spores, they are formed by a cell wall composed of chitin and also in some fungi it contains cellulose. They divide into asexual spores called conidiospores and sexual spores or zygospores and ascospores. These characters of the spores and the biological cycle of the fungi are decisive for the taxonomic classification of the fungi, although many species still do not have a defined class.
Features
Before they were classified as part of the plant kingdom, due to their own characteristics, botanists specializing in mycology grouped them within a specific kingdom, the Fungi kingdom. The particularities that distinguish fungi from plants, as they are heterotrophic organisms (they produce their own food), their cell walls are made up of a biopolymer called chitin and they lack cellulose. Currently, more than 144.000 species of fungi have been described, including yeasts, molds and mushrooms.
Fungi can be unicellular or multicellular, the latter when they are in their vegetative phase form mycelia, which are composed of hyphae. The hyphae are made up of several cells and have elongated shapes; the cells that make up the hyphae each contain essential cellular components for the proper functioning of the entire hyphae.
Mushrooms can be found in different habitats around the planet earth, with different shapes and presentations. In addition, the well-known mushroom-shaped fungi, with a speckled cap with a long white body, are just forms in which fungi appear because even microscopic fungi exist. Mycologists estimate that 5% of the planet's fungi have been identified so far, which means around 1,5 million unidentified fungal species.
Their reproduction can be sexual and asexual, these sporulate depending on the climatic conditions to spread and colonize surrounding environments, they remain dormant in adverse conditions. The so-called true fungi, such as mushrooms and macromycetes, form a fruiting body that most of us know and give it the name of fungi, these can be edible or poisonous. Although they do not have the macroscopic characteristics of mushrooms, yeasts and molds are also fungi.
Origin of the Mushrooms
For more than a billion years, fungi have differed from other kingdoms, but resemble plants in the lack of locomotion mechanisms and some body structures, but do not contain chlorophyll. They also resemble protists in their biochemical makeup. Fungi are organisms with a true nucleus or eukaryotes, so they form a more modern evolved branch with respect to the prokaryotic organisms of the Monera kingdom.
Taxonomic Classification
The Fungi kingdom groups more than 98.000 species of classified fungi. The Basidiomycota and Ascomycota phyla are the fungi that have been studied the most in this kingdom and are called "true fungi". This occurs given that for most species it is only feasible to study their sexual stage in the field, and for this reason most of the described fungi have been achieved by being able to study their reproductive forms: asexual or anamorphic and sexual or teleomorphic.
Until now, five representative phyla of the Fungi kingdom have been described, this is because the taxonomic classification of the Fungi kingdom is still under study due to the fact that there are a number of species without being classified. According to phylogenetic studies, fungi are classified into five large groups:
Chytridiomycetes
This group of fungi includes all the microscopic organisms of the Fungi kingdom, which have reproductive cells called zoospores or flagellated gametes.
Glomeromycetes
These fungi are characterized by forming mycorrhizae that are associated with plants, and also have glomerospores.
Zygomycetes
In this group of fungi are commonly known as molds, of this group about 1.000 species have been studied. The spores of this group of fungi are called zygospores.
ascomycetes
This group of fungi inside the asci that are reproductive structures, containing ascospores.
basidomycetes
These fungi have basidiospores and a fruiting body in mushroom shapes.
Chytridiomycota or Chytridiomycetes Group
The fungi that are part of the Chytridiomycota or Chytridiomycetes group are fungi with simpler morphological structures, they live in aquatic habitats such as estuaries, streams, lagoons and marine habitats in which they move. Its reproductive structure or spores, are called zoospore and have a single flagellum. The fungi of this group can remain inactive for a long time if the environmental conditions are adverse.
The fungi of the Chytridiomycota group are parasites of other planktonic organisms that are found in the water, they can be found in crops of the botanical families Curcumitaceae and Solanaceae, which are found near flooded soils, although it is common to find them in bodies of fresh water and salty
According to some mycologists, this group of fungi is an important part of the food webs of aquatic habitats. In their form of zoospores they provide nutrients as they are food for zooplankton. Likewise, they control their natural predators, by decomposing organic matter, parasitizing animals and some plants.
Glomeromycota or Glomeromycetes Group
This group of fungi has the particularity of forming symbioses with plants and in which the oldest and most fossil species are recorded. They are called mycorrhizal fungi because they form a mycelium near the rhizome of plants. Mycorrhizae release enzymes into soils that react with soil elements and make them bioavailable for plant uptake as nutrients.
The symbiotic association between mycorrhizal fungi and plants is carried out between 80% of the plants. Its taxonomic peculiarity of this group of fungi is the formation of plurinucleate spores for sexual reproduction. Mycorrhizal fungi are divided into: arbuscular mycorrhizae and vesicular mycorrhizae, these are the macroscopic forms of the mycelium. Arbular mycorrhizae form branches called arbuscules, and vesicular mycorrhizae form nodes with reserve substances.
Zygomycota or Zygomycetes group
The well-known molds are located in this group of fungi, some 1.000 species have been described, their spores are called zygospores. In this group of fungi they usually develop in terrestrial habitats, in decomposing matter, as parasites and also forming symbiotic relationships. An example of Zygomycota fungi is the bread fungus.
They reproduce sexually and asexually, but the most common way of reproducing is asexual and occurs when the haploid hyphae approach each other until they meet so that the fusion of the cytoplasms happens and therefore the fusion of the nuclei, in this fusion occurs the zygospore, which is the reproductive structure of the group.
The zygospores are very resistant to adverse conditions, they remain dormant until the environmental conditions are good for them, the zygospores germinate and a sporangium or vegetative hypha is produced. This type of fungi is used to produce foods such as tofu and tempeh, to produce anesthetics, meat tenderizers, food dyes and also industrial alcohols.
Ascomycota or Ascomycetes Group
Most of the fungi described from the Fungi kingdom are part of this phylum or Ascomycota group, in this group there are a large number of pathogenic species to animals and plants. An example of Ascomycota fungi is yeast. The morphology of the mycelium of the fungi that form this group allows filamentous fungi to group together, this occurs through the septa, which are divisions that occur in the hyphae. Their reproductive spores are flattened (ascospores) and agglomerated in sacs called asci.
Fungi in this group are used in the food, medical, and agricultural industries. For example, the yeast used to make bread belongs to this group of fungi; its scientific name is Saccharomyces cerevisiae, and it is used to accelerate the fermentation process of flour in breadmaking.
In contrast, other yeasts cause infections and medical conditions, such as fungi of the genus Candida spp. Filamentous fungi, such as species of the genus Fusarium spp., are of agricultural importance due to the losses they cause in crops. Some species of Fusarium spp. produce mycotoxins in cereal production, causing losses because these fungi are harmful to the health of people and animals. The toxins produced by these fungi include fumonisins, trichothecenes, and zearalenone.
Basidiomycota or Basidomycetes Group
It is the second most studied group of fungi, to date 32.000 species have been described. This group of fungi have different morphologies that lead to placing them in different groups of fungi, which after carrying out genotype studies are relocated to the Basidiomycota group. In this group of fungi, fungi with setae are located, which are exospores that form in a fruiting body called a basidium.
These fungi form symbiotic associations with insects, this relationship allows them to be hosts or break down substances of specific compounds. Basidomycetes can be seen on the trunks of fallen trees that decompose in forests, especially if they are tree trunks rich in lignocellulose. In these cases, these fungi release hydrolytic enzymes through their mycelium, which are catalysts for polymers that degrade the wood of the trunk.
Just as some other fungi of the basidomycetes group are toxic, they are edible, very well used as a gastronomic alternative, due to the micronutrients they contribute, such as mushrooms. Likewise, other basidomycete fungi are used to treat diseases in different parts of the planet.
Reproduction of Fungi
Fungi have two types of reproduction: sexual and asexual. The way to reproduce sexually is the most common, causing genetic differences, to achieve this type of reproduction you have to find a compatible individual. Fungi that reproduce asexually allow the environment to colonize. Both types of reproduction have advantages and disadvantages for organisms.
Sexual reproduction
This type of reproduction depends on the affinity between the hyphae of the same Homothallic organism, or a nearby Heterothallic individual of the same species or genetically close so that the hyphae are recognized. The crossing of fungi is conditioned by compatibility, which is highly dependent on genetics and chemical factors that help the proximity of a compatible hypha.
Fungi that reproduce sexually and are Homothallic fungi can form, from the same thallus or mycelium, male or female structures. On the other hand, Heterothallic organisms can also form male or female structures, or both structures on the same thallus. To form both structures on the same thallus, it has to have another compatible individual.
Asexual reproduction
Fungi reproduce asexually or vegetatively, this way of reproducing occurs in a large number of fungal species, at some point in their life cycle. This type of reproduction allows to cause a growth of the fungal mycelium, which results in the colonization of a particular substrate, which already has the genes indicated to survive.
In addition to the two common types of fungal reproduction, asexual sporulation also occurs, which is the formation of spores by mitosis (mitospores) and many filamentous fungi can divide so that the aforementioned fragments form complete individuals, this It generally occurs in organisms of the phylum Basidiomycota.
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