Question

State what is apomixis. Comment on its significance. How can it be commercially used?

Answer 1

Hint: Apomixis is a type of asexual reproduction in plants in which sexual organs of related structures take part but seeds are formed without union of gametes. It is also called clonal seed production. Apomixis is of three types, diplospory, apospory and adventitious embryo.

Complete answer:
Apomixis is a word derived from Greek language where ‘apo’ means away from and ‘mixis’ means mixing. It is a type of asexual reproduction in plants in which sexual organs of related structures take part but seeds are formed without union of gametes. It is also called clonal seed reproduction. It is more common in higher plants, for examples, Rosaceae, Compositae, etc. Apomixis is of three types
- Diplospory- in this embryo sac is developed from the megaspore mother cell either by meiosis or interrupting meiosis.
- Apospory- in this, the nucellar gives rise to the apomictic embryo sac. It is one of the most common types of apomixis in higher plants.
- Adventitious Embryony- it is also called sporophytic apomixis. In this embryo are produced directly from the nucleus or integument of the ovule.
Apomixis is significant for hybrid seed production. It is also one of the most cost-effective methods to produce seeds. It prevents the loss of specific characters in the hybrid. It allows plant breeders to fix heterosis.
Commercial uses of apomixis:
- It is used for fixation of heterosis
- Used in plant breeding.
- For fixation of heterozygous state
- Rapid production of homozygous lines
- Production of phenotypically stable populations.

Note: Apomixis has some cons associated with it. It is a very complicated phenomenon. The genetic basis of apomixis is not clear in most cases. Apomictic seeds tend to reduce the genetic diversity due to lack of variations in asexual reproduction. Genetic mutation can also result in apomictic seeds.