Question

Polyembryony is the formation of more than two embryos in a single ovule. It is classified into
cleavage polyembryony and adventive polyembryony depending on which cells form the second
embryo. State the difference.

Answer 1

Explanation:

An embryo develops directly from a diploid cell other than egg like that of nucellus and integument, e.g., Citrus, Opuntia. It gives rise to a con­dition called polyembryony or the phenomenon of having more than one embryo. There may be more than one egg cell in an embryo sac or more than one embryo sac in an ovule.

All the egg cells may get fertilised. Synergids and antipodal cells may also form embryos. In gymnosperms polyembryony can also occur due to cleavage of growing em­bryo. It is called cleavage polyembryony.

Occurrence of polyem-bryony due to fertilisation of more than one egg is called simple polyembryony. Formation of extra embryos through sporophytic budding is called adventive polyembryony. Polyem­bryony is quite common in Onion, Groundnut, Mango, Lemon, Orange.