Question

write a note on the development of endosperm

Answer 1

ENDOSPERM DEVELOPMENT

• Endosperm is the nutrive tissue formed from vegetative ferilization in flowering plants.

• It supplies food materials to the growing embryo and also the seedling.

• Based on the mode of development, there are three types of endosperm development.

• They are nuclear type, cellular type and helobial type.

• In nuclear type of endosperm development, primary endosperm nucleus (3n) undergoes free nuclear divisions to form numerous nuclei without any immediate wall formation.

• These nuclei are then arranged at the periphery.

• As a result, a large vacuole is formed at the centre of the embryo sac.

• Later the wall formation (cytokinesis) starts from periphery towards the centre.

• A multicellular endosperm is formed by nuclear divisions.

• Each nuclear division is followed by cytokinesis (wall formation).

• Therefore the endosperm is of cellular type.

Answer 2

Endosperm is formed from the primary endosperm nucleus. Its formation starts before the formation of embryo. Primary endosperm nucleus is produced by fusion of monoploid polar nuclei (secondary nucleus) and a monoploid second male gamete. The endosperm is thus triploid (3n).