We explain what sporulation is, how this mechanism of asexual reproduction works, examples and other forms of reproduction.
What is sporulation?
Sporulation is the spore formation process (a mechanism of asexual reproduction) and endospores (a very resistant form of life that occurs in some bacteria). In both cases, sporulation involves the formation of structures capable of withstanding various environmental conditions.
Spores are sex cells modified to resist and are part of one of the mechanisms of asexual reproduction. They are found in most fungi and many plants, at least at some point in their life cycle.
Endospores are a particular form of organization that certain bacteria acquire when they are under conditions of lack of nutrients in the environment. Bacterial cells go through a process in which they reduce their internal content and create a strong cell wall. Endospores can withstand very hostile conditions for a long time, even years. Ancient endospores have been found that have resisted radiation, desiccation and high temperatures.
Although they have some similarities with sexual cells (gametes), spores are characterized by their great resistance.
A spore is a single cell wrapped in a thick layer of organic material, which defends it from unfavorable environmental conditions. When conditions become more advantageous, the spore begins to grow and develop to form a complete individual, without needing to fuse with another cell.
In addition to sporulation, there are other mechanisms of asexual reproduction such as budding, binary fission and parthenogenesis.
- See also: Reproduction
In which organisms does sporulation occur?
Sporulation is a reproduction mechanism that occurs in almost all fungi, some types of plants and certain species of bacteria.
1. Sporulation in fungi
In fungi, sporulation takes place in specialized structures known as asci, basidia, conidiophores or sporangia, depending on the type and species of fungus.
Spores are released into the environment, usually aerially, and transported via wind to new destinations. Spore-producing fungi belong to the ascomycetes, basidiomycetes, conidiophores (imperfect fungi), zygomycetes, glomeromycetes or chytrids.
- It may help you: Reproduction of mushrooms
2. Sporulation in plants
Many plants have a mechanism that alternates between reproduction through spores and reproduction through sex cells (gametes).
Both spores and gametes originate from a special type of cell division called meiosis. The difference is that spores can give rise to a complete individual without the need to fuse with another cell. Instead, gametes need to encounter another sex cell to begin development from an egg or zygote cell.
Pteridophyte plants (such as ferns) are a classic example of sporulation in plants.
- See also: Plant reproduction
3. Bacterial sporulation
Some bacterial species, such as those of the genus Bacillus and Clostridium, They have the ability to survive hostile environmental contexts through the formation of endospores.
Endospores are a form of life that form when a bacteria becomes a “sleeper cell,” because its entire metabolism is at rest. They are not reproductive structures, but rather survival ones.
Under conditions of nutrient deprivation, the bacteria reduces its cytoplasm to a minimum and then wraps it in a cover of peptidoglycan, a substance that provides rigidity and resistance.
Other forms of asexual reproduction
In addition to sporulation, there are other non-sexual reproduction mechanisms (that is, those that involve a single individual and have little or no genetic variation):
- Binary fission. It is produced by division of the body of one organism to form two others. It is the way bacteria reproduce. The offspring are genetically identical.
- Gemmation. It consists of the formation of extensions or prominences of the parent's body, which are a “miniature copy” of the adult organism. Then, they separate and have independent lives. This mechanism happens, for example, in sponges and hydras.
- Parthenogenesis. It consists of the development of a new individual, although genetically equal to the parent, through the development of unfertilized female sex cells. All of the cells in the new organism are haploid (they have a single set of chromosomes, instead of two). It is an atypical form of reproduction and occurs in small invertebrates (such as bees and ants), which usually alternate parthenogenesis with sexual reproduction. It can also occur in larger animals, such as snakes.
References
- Audesirk T., Audesirk G., Bruce E., BIOLOGY 3: Evolution and ecology. 6th edition. Pearson education (2003).
- Iáñez, E. (2005). Endospores and other differentiations of the prokaryotic cell. University of Granada. https://www.ugr.es
