What is Apomixis and What is its Importance in Plants?

In this tutorial, we have discussed “What is apomixis and what is its Importance in plants?”

What is Apomixis

The formation of new individuals through the normal process of sexual reproduction by the meiotic formation of gametes and their subsequent fusion during fertilisation is called amphimixis. The formation of new individuals through asexual reproduction without the formation and fusion of gametes is called apomixis.

It occurs in certain plants such as grasses and species of the family Asteraceae. These plants produce seeds without fertilisation. The plants that show apomixis are called apomictic plants

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Apomixis is a form of asexual reproduction that mimics sexual reproduction. The term apomixis was coined by Winkler in 1908.

Apomixis Example

Apomixis is broadly separated into two types: Vegetative propagation and Agamospermy.

01. Vegetative Propagation

In this type, new plants develop from the stem, leaf, buds, etc. No seed is formed and the formation of flower is not required.

02. Agamospermy

In this type, haploid gametes are not formed. Seeds and embryo are formed without meiosis and fertilisation. Agamospermy can be of the following types:

(i). Adventive Embryony

An embryo is formed from a diploid cell of nucellar tissue or integument, but never from an egg, e.g., Citrus, Opuntia, Mango, etc.

(ii). Recurrent Apomixis or Recurrent Agamospermy

A diploid embryo sac is formed with a diploid egg. The diploid egg grows partenogenetically into diploid embryo.

(iii). Non-recurrent Agamospermy

In this case, an embryo develops from a haploid female gamete without fertilisation (haploid parthenogenesis).

(iv). Apospory

Development of diploid gametophyte on the sporophyte without reduction division is called apospory

. In this process, embryo sac develops from a sporophytic cell (2n) of the ovule. Thus, the egg within the diploid embryo sac is also diploid and develops into a diploid embryo. This is also called diploid parthenogenesis.

(v). Apogamy

It is the formation of an embryo from any cell of the embryo sac other than an egg without fertilisation. The embryo usually develops from synergids or antipodal cells. Apogamy is seen in the Orchids of the family Orchidaceae.

(vi). Diplospory

Here diploid embryo develops directly from megaspore mother cell.

Importance of Apomixis

 01. Apomixis provides a better alternative for raising hybrid cereal and vegetable crops from hybrid seeds. Hybrid seeds have to be produced every year as they cannot be collected from the hybrid plants. If apomixis is introduced in the hybrid seeds, there will be no need of producing seeds every year. This will save time and money.

02. Embryos formed through apomixis are free from infectious diseases.

03. Adventive embryos (more than one embryo in a seed) are better clones than plants produced from cuttings.