Question

In angiosperms, sometimes it is seen that an embryo maybe formed from the deploid cells of the nucellus. It is a case of _________________

• A. Apospory
• B. Parthenocarpy
• C. Parthenogenesis
• D. Polyembryoniy

Answer 1

Answer:

D. Polyembryoniy

• Polyembryony refers to the occurrence of more than one embryo in a seed.

• The formation of an embryo from the diploid nucellar cells is a type of adventitious embryony, which falls under the general category of polyembryony. The nucellar cells are sporophytic (diploid) and typically differentiate to form an embryo directly, bypassing the usual processes of meiosis and fertilization. This is known as nucellar embryony.

• This phenomenon is common in certain groups like Citrus (Citrus) and Mango (Mangifera indica).

• a) Apospory: This is the formation of a diploid embryo sac (gametophyte) directly from a diploid sporophytic cell (like a nucellus cell) without meiosis. It doesn't refer to the formation of the embryo itself, but the preceding gametophyte generation.

• b) Parthenocarpy: This is the development of fruit without fertilization, resulting in seedless fruits (e.g., bananas). It is unrelated to embryo formation.

• c) Parthenogenesis: This is the development of an embryo directly from an unfertilized egg cell. The egg cell is typically haploid, and this process is a form of apomixis (asexual seed formation), but it specifically involves the egg cell, not the diploid nucellus cells.