Question

Write a short note on polyembryony.

Answer 1

A seed is formed after fertilization of ovule. Generally, each seed bears an embryo but sometimes more than one embryo is found in a single seed. This occurrence of more than one embryo (from a single fertilized egg) in a seed is called polyembryony and it was first observed in orange seeds by Antony von Leeuwenhoek in 1917.

• There are two types of polyembryony:
  

1. Gametophytic Polyembryony -
It arises from the haploid cell i.e. gametophytic cell of the embryo sac without fertilization or after fertilization.

2. Sporophytic Polyembryony -

Here, embryos arise from the diploid cell or sporophytic cell of the embryo sac i.e. from cells of pre-embryo or nucellar cells or integumentary cells.

• Significance of polyembryony:
  

1. Seedlings develop a better root system and show better yield.

2. Seedlings are free from diseases.

3. For large scale production of uniform plants, induced polyembryony is very suitable.

4. Artificial seeds can be formed by somatic embryos which are also suitable for field planting.