Plants have a lot of propagation and reproduction mechanisms to ensure their survival and colonize new territories, something that is not in vain because they have been here much longer than us.
Among the many forms of multiplication they have at their disposal, one of them allows them to produce seeds in asexual way, that is, without needing another plant to fertilize the ovules. How is it possible that seed reproduction, the method of sexual reproduction, occurs precisely in a asexual way? Thanks to the Apomixis. If you want to learn more about this reproductive mechanism, keep reading in this ecology article about What is Apomixis, its types and examples.
What is the Apomixis
The Definition of Apomixis says it is a reproductive mechanism that allows the plant to be cloned by its seedsinstead of producing them sexually as usual. It is, therefore, a form of asexual reproduction by production of APOMICTICS.
Like other forms of asexual reproductionis characterized by offering plants that use it a greater ease of propagation and colonization in exchange for sacrificing genetic variability and adaptation ability that it provides from an evolutionary point of view. Thus, it is an ideal mechanism for the survival of the species in environments to which it is already adapted, simply providing a greater presence.
Apomixis occurs without meiosis presence, that is, without the embryo being formed from the fertilization and generation of viable endosperm. APOMICTIC SEEDS are formed only from the maternal ovum and, therefore, are genetically equal to the mother plant. It is a very common mechanism in many families and genres, as we will see later.
We also recommend you read more about asexual reproduction in plants: what is, characteristics, types and examples in this other post.
Types of Apomixis
Three are known Types of Apomixis mechanisms:
Diplosporia
In Diplosporia, also known as a parthenogenesis diploid, the embryo arises from an underived embryonic sack, so the new individual has the same chromosomal number as the parent plant. This type of apomixis occurs when the female Gametophyte is formed directly from the embryo. In diplosporia, there is always a presence of a diploid embryo.
Aporia
Aplosporia is an asexual type of reproduction in which it is the somatic cells that give rise to the embryonic sack. This arises specifically from a somatic cell located in the nucle around its stem cell. Here appears a Gametophyte, but not because of meiosis, so the embryo is diploid too. The chromosomal number is also not reduced in the bet.
Adventitious embryo
Adventicia embryony, also called sporophytic apomixis or nuclar embryo, is a very common type of fruit in fruit trees, specifically in citrus fruits. In this type of apomixis there is no appearance of embryonic jacket, since the embryo arises from a diploid sporophyte, without meiosis or appearance of female Gametophyte.
Examples of Apomixis
The first example of Apomixis, which coincides precisely with the appearance of the term, occurred in 1841, when Kew’s botanical gardens in London welcomed a specimen of Australia, Alchornea ilicifolia. It was a female plant that, being isolated, produced flowers and, to the surprise of those responsible for the Botanical Garden, a large number of seeds. It was evident that, without viable pollination options, the plant had produced seeds in a totally asexual way, thus recognizing the first documented case of Apomixis.
Shortly after, Gregor Mendel, when he experimented with some species of Hiracium, would give rise to the first involuntary case of experimentation with Apomixis, in a process he called, erroneously, self -pollination.
Another of the most common examples of Apomixis It is the one of León tooth, scientificly Taraxacum officinalis. This plant frequently uses cloning by apomixis to multiply, spreading its seeds with its characteristic ability to be taken away by the wind. The lion teeth Able to resort to Apomixis, they also enjoy more geographical distribution than those species that cannot do so, thus demonstrating the success of this asexual reproduction mechanism in the appropriate conditions. Of course, even lion tooth species that Apomixis usually use occasionally resort to sexual reproduction, even hybridizing, and it is rarely advisable to close completely to genetic variability and its adaptation capabilities.
We also find cases of Apomixis in practically all species of the Poaceae family, calls grassesa family of great economic importance for the human being, with more than 800 genres and 12,000 species described. In fact, in this area specifically, it is studied how to take advantage of the apomixis in crops of grass plants as vital as corn and wheat, since it would easily improve the quantity and quality of production.
Other genres in which this asexual reproduction mechanism is usually found are Asteraceae, Rosaceae and Rutaceae, plants that surround us very commonly and with a large distribution.
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