Ontogeny of endosperm tissue and seed coat in Zygophyllum fabago

Regarding the developmental importance of endosperm tissue and seed coat, the study of the ontogeny of endosperm and seed coat sculptures was considered in current research using microscopic techniques. The samples were collected from different developmental stages. Then, the fixed samples were studied by different histochemical methods. The observations indicated that the ovule was of the anatropous and bitegmic type which the inner integument was comprised of 3-4 distinct cell layers. The inner epidermis cells regularly wrapped around the embryo sac and are retained up to the end of seed development, whereas the other layers were removed in the early stages. Moreover, the outer integument was made up of two layers of cubic-shaped cells, and the external layer was changed into the seed coat sculptures during the seed development. Thus, the seeds of Z. fabago were categorized of testal type. During the early developmental stages, the endosperm was of nuclear type and then changed into the cellular type. In the later stage of seed development, the formation of starch grains and the strongly thickening of cell walls were occurred, causing considerable reduction of cell cavities as well as hardening of this tissue.

Keywords:

Bitegmic , Exotesta , Embryo , Histological techniques , Nuclear endosperm