Dicot embryogenesis

1. DICOT EMBRYOGENESIS
PRESENTED BY
KIRAN DASANAL
(PALB7319)

2. BEFORE DICOT EMBRYOGENESIS
 Double fertilization and triple fusion takes place.
 Zygote formation by double fertilization.
 Endosperm formation by triple fusion .

4. DICOT EMBRYOGENESIS
 After fertilization the egg cell or ovum secrets a cellulose wall
arround it and beome the “oospore”.
 Later it divides into two cells-an upper (away from the
micropyle) and the lower (towards the micropyle).
 Lower cell-become suspensor-act as feeding organ/absorbing
organ.and become disorganised as the radicle is formed.

5. CONT….
 The upper cell is called embryonal cell.It enlarges and divides
by four walls at right angles into eight cells (octants).
 Few cells lying towards the suspensor forming the posterior
octants and the other four cells lying away from suspensor
forming anterior octants.
 Each octant then divides by a wall,parallel to its curved
surface.

6. CONT….
 Thus, a surface(superficial) layer of cells and a central mass of
cells (embryonal mass) are formed.
 The surface layer divides in one direction by radicle walls
only and remains single-layered,which gives rise to
dermatogens.
 Dermatogens-The outer layer of stem apex and root apex.

7. CONT….
 The cells of the embryonal mass gives rise to the whole of the
embryo except at the root tip.
 The cells of the embryonal mass divides repeatedly and the
various parts of the embryo become differentiated.
 Thus it is seen that the “plumule” and two cotyledons are
derived from the anterior octants and the main part of the
radicle and hypocotyledons from the posterior octants.
 The apex of the radicle is derived from the hypophysis cell.

8. Dicot embryogenesis