Question

Describe apomixis and its significance in plants.

Answer 1

Hint: Apomixis result in the formation of seeds without fertilisation. This phenomenon is found in some angiosperms particularly in grasses. Apomicts have several advantages in agriculture and horticulture.

Complete answer:
In flowering plants, seeds are the product of fertilisation but some species like Asteraceae and grasses have developed special mechanisms to produce seed without fertilisation, called apomixis. It is a form of asexual reproduction which mimics sexual reproduction. The progeny is similar to its maternal genotype because the female gametophyte that is ovule in the flower is directly converted into an embryo without undergoing the syngamy and meiosis.
Significance of apomixis in plants are as follow –
> It is a time-efficient and cost-efficient process for the formation of seeds.
> There is no segregation of character in the hybrid progeny.
> The progeny is exactly like the mother plant.
> It helps in the preservation of good characters for a long period.
> The hybrid seeds are produced with a combination of desirable characters.
> The seed produced by apomixis is useful for the formation of uniform rootstocks in citrus, apple, etc.
> Viruses screening is suitable by Apomictic seedlings as it’s not transmitted through seeds.

Note:
Apomictic seeds can be produced in several different ways. In some species, the diploid egg cell is formed without meiosis (reduction division) and develops into the embryo without fertilisation. However, in citrus and mango varieties, the embryo sac is surrounded by the nucellar cells and developed into an embryo. In such species, each ovule may contain many embryos. The development of more than one embryo in a seed is called polyembryony.