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Published on May 27, 2018

Author: Dasanal

Source: authorstream.com

DICOT EMBRYOGENESIS: DICOT EMBRYOGENESIS PRESENTED BY KIRAN DASANAL (PALB7319) BEFORE DICOT EMBRYOGENESIS: BEFORE DICOT EMBRYOGENESIS Double fertilization and triple fusion takes place. Zygote formation by double fertilization. Endosperm formation by triple fusion . DICOT EMBRYOGENESIS: 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. CONT….: 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. CONT….: 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. CONT….: 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. Dicot embryogenesis: Dicot embryogenesis

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