EMBRYO SAC DEVELOPMENT AND EMBRYOGENY IN ALLIUM TUBEROSUM

The development of the embryo sac of Allium tuberosum belongs to Allium type. In mature embryo sac, three antipodal cells often resemble to egg apparatus: two are like synergids and one is alike to egg cell. The type of embryogeny is Onagrad with the embryo proper principally derived from the apical cell of 2-celled proembryo The egg-like antipodal cells may divide and form multicellular proembryos which degenerate with the development of endosperm, indicating that the latter may exhibit an inhibiting effect to the antipodal proembryos. In some unfertilized embryo sacs, egg cell and egg-like antipodal cell may also divide, they are similar to zygote in embryogeny. However, these proembryos can not continue to develop because of absence of endosperm to nurse them. The concept of antipodal embryo and the relationship of antipodal apogamy with endosperm are discussed.