We explain what sporulation is, how this asexual reproduction mechanism works, examples and other forms of reproduction.
What is sporulation?
Sporulation is the mechanism of asexual reproduction through spores and endospores . This type of reproduction is usual in fungi, plants and various genera of bacteria and microorganisms . It can be part of its natural reproductive cycle, or an alternative to face adverse environmental situations, such as lack of nutrients or sunlight.
Although they are similar to animal gametes, the spores are characterized by being resistant structures : they consist of a single cell wrapped in a thick layer of organic material , which defends it from hostile environmental conditions, waiting for a more favorable situation to develop a complete individual
They are known to be tremendously resistant to radiation, desiccation, heat and even the passage of time . They are divided into:
- Endospores , which form within the body , usually unicellular .
- Exospores , which are formed outside the body, through a process called budding.
Next, we will see as an example sporulation in plants, fungi and bacteria:
- Bacterial sporulation . It consists of the replication of the bacterial DNA , wrapping it in a small portion of the cytoplasm , covering it after peptidoglycan as the spore hardens and is finally released into the cellular medium. This procedure is commonly carried out by the bacteria of the genera Bacillus , Clostridium and some cyanobacteria.
- Sporulation in fungi . The procedure in fungi is similar to bacterial, as genetic replication occurs through mitosis , except that in the case of multicellular fungi this process is carried out in specialized structures known as ascas, basidios, conidiophores or sporangia, depending of the type and species of fungus. These are then released to the environment , usually by air, and transported by wind to new destinations. Spore-producing fungi belong to ascomycetes, basidiomycetes, conidiophores (imperfect fungi), zygomycetes, glomeromycetes or chytrid.
- Sporulation in plants . Many species of plants have a reproductive mechanism that alternates from one generation to another, between spore production and gamete production. Many of these spores are differentiated into female and male, just like animal gametes, since they are formed by meiosis (and not by mitosis). These spores are classified into microspores (which give rise to pollen) and macrospores (which give rise to the ovules inside the flower). It is known that both angiosperms and gymnosperms resort to this reproductive method, as well as green algae, rhophyll algae and other known types.
Other forms of asexual reproduction
In addition to sporulation, there are other mechanisms of non-sexual reproduction (that is, they involve a single individual and have little or no genetic variation), such as:
- Binary fission . Typical of unicellular organisms, it consists in the replication of DNA and cellular content, until it forms a double individual that will then be separated, by narrowing the plasma membrane , into two new genetically identical individuals.
- Budding . It consists of the formation of extensions or prominences of the parent’s body, which can then be separated from it and have a life of their own, or remain together and start a colony. It can also occur at the cellular level, as an asymmetric mitosis process.
- Parthenogenesis . Typical of certain animals (flatworms, rotifers, tardigrades, insects, amphibians , fish and crustaceans , but also some reptiles ), it consists in the development of a new individual, although genetically equal to the parent, through the development of unfertilized female sex cells.