BIOLOGY

What is the reproduction of fungi?

We express the reproduction of fungi and the characteristics of these living things. Also, how is your sexual and asexual reproduction.

What is the reproduction of fungi?

Fungi are living beings belonging to the Fungi kingdom ( phylum ) , composed of multicellular eukaryotic beings other than plants and animals. They are characterized by being immobile, heterotrophic ( decomposers ) , and having very varied shapes and cells with a chitin cell wall (instead of cellulose, such as plants).

Fungi can be microscopic or macroscopic , they can be free-living or parasitic , and they are found in extremely diverse habitats . Some species are edible for humans or are used by them in their various industries, as is the case with yeasts in the production of beer and bread.

Likewise, the reproduction of fungi is different from that of plants and that of animals , since they do not have stomata, nor flowers, like plants, but they do not copulate like animals. On the contrary, fungi reproduce by spores , which are germ cells produced by both sexual and asexual methods.

These spores are dispersed by wind, animals or other mechanisms, and remain dormant for a long time, waiting for the conditions to be conducive to their germination.

When these conditions occur , they give birth to a first hypha. A mycelium is gradually constructed from it , and in some cases it can grow dramatically fast (certain tropical fungi grow at a rate of 5mm per minute).

Asexual reproduction of fungi

asexual reproduction of fungi fungi
Fungi that are born by asexual reproduction are genetically equal to the parent.

Asexual reproduction of fungi occurs through the formation of spores of the same type of sexual compatibility as the adult individual. Spores are formed in sporangia , which are called specialized structures.

Once mature, the latter allow the release of the spores so that the wind disperses them, and eventually they find the ideal conditions to germinate. If this happens, the resulting individual will be genetically equal to their parent , that is, a genetic copy of it.

Sexual reproduction of fungi

sexual reproduction of fungi fungi
Some rhizopus mold species reproduce sexually.

The sexual reproduction of fungi involves two individuals that exchange genetic material , analogously to what happens with animals and with plants of sexual reproduction.

The exchange is carried out through progametangios . These specialized structures are able to merge if they find one of the compatible sexual type (designated – and +, since there are no males and females).

When fused they form a multinucleated cell called zigosporangio , from which a single zigospora arises. Thus begins a genetically new individual, different from its two parents.

Dioecious fungal species

Mushrooms

Mushrooms in forest

Generally, the heterogametic species of fungi that produce gross male and female sexual structures are known as dioecious species of fungi. In these cases the fungi only produce the sexual organs in the presence of an individual of the opposite sex.

Despite the above, it is common for the same individual to carry the male and female sexual organs, and that is why some fungi are considered hermaphroditic organisms.

Fusion of two nuclei

As in all eukaryotic organisms, sexual reproduction in fungi involves the fusion of two cell nuclei with half of the chromosomal load of the individuals that produce them, which necessarily implies a prior meiosis process to reduce said genetic load .

How is the proccess?

Sexual reproduction is a process that ensures the production of new genetic combinations within fungal populations.

Usually these novel combinations allow them to acquire the necessary changes in genetic information to adapt to new environments that have challenging conditions for their survival.

Sexual reproduction in fungi consists of three processes: plasmogamy, karyogamy and meiosis, namely:

Plasmogamy

It is the fusion between the cell membranes of the two gametic cells with haploid nuclear charge (n). This fusion of the membranes allows the two nuclei of the gametic cells to approach and later fuse.

Karyogamy

In karyogamy, the fusion of the two gametic nuclei (n) originates a diploid nucleus (2n) called a zygote. The zygote is a well-defined uniform mass of genetic material that can be easily seen with a light microscope.

Meiosis

Meiosis occurs to restore the haploid condition of the gametic nuclei. The fusion of the two haploid nuclei gives rise to 4 new recombinant haploid nuclei (n).

If unfavorable conditions occur during sexual reproduction, some species of fungi can delay or slow down the meiosis process and remain for long periods of time in a diploid (2 n ) or dikaryotic ( n + n ) phase , that is, with two nuclei haploid.

Sexual reproduction culminates in the production of spores that tend to group into structures known as sporangia.

Microscopic view of the sporangium of a fungus

Microscopic view of the sporangium of a fungus

Reproduction of fungi and spore-bearing structures

Species that reproduce sexually and asexually can generate different types of spores, which are relevant when addressing the topic at hand: the reproduction of fungi.

In the reproduction of fungi, sexual type, there are mainly three structures, which are characteristic of three representative phyla of the Fungi kingdom, these structures are: zygospores, ascospores and basidiospores. Zygospores are common in the phylum Zygomycota and are harbored in sporangia; the ascospores of the Ascomycota phylum are stored in conidia supported by conidiophores, finally the basidiospores await in basidia and occur in the Basidiomycota phylum. However, there are asexually produced spores that are also stored in structures with variable morphology and location.

In the reproduction of fungi there are exogenous and endogenous asexual spores, the endogenous ones, in general, are presented in sacks or storage bags and allow internal asexual reproduction. The endogenous ones are of the sporangiospores or zoospores type, the latter present in “chytridia”. The exogenous ones can be blastospores, arthrospores or chlamydospores, arthrospores can occur in Ascomycota and Basidiomycota, while blastospores are more common in Glomeromycota.

Parasexual reproduction of fungi

In some species of fungi it has been observed that recombination (mixing of the genetic material between chromosomes) typical of sexual reproduction (meiosis) can occur but during mitotic reproduction.

This type of reproduction is called parasexual reproduction and is common in many species of fungi and some of bacteria.

Parasexual reproduction involves the fusion of two genetically different haploid nuclei (n) to form a diploid nucleus (2n) that then undergoes a loss of genetic load until it becomes haploid (n) again, but with different genetic information to any of the parental nuclei.

Parasexual reproduction is very particular in nature and it is not yet understood why it occurs, or many of its mechanisms.

However, this type of reproduction helps many species of fungi that only reproduce clonally (asexually) to increase their rate of genetic variability in the absence of the meiosis characteristic of sexual reproduction.

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