Comparative ultrastructure on seed formation on crop and underexploited plants

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After 2 days of anthesis, rice embryos are composed of more than 60 cells, one of which is abutting on nucellus with promising the development to suspensor in future. In the basal part of these embryos, the cells distinctly have cell wall and plasmodesmata are concentrically present into the pocket of central cell. In the upper part of these embryos, there are deposition of low dense substances in the space between the plasma membranes of embryo cells and central cell. In this stage, there are degenerated tissues in the pocket and pollen tube traces in the nucellus. After 3 days of anthesis, rice embryos have approximately 200 cells. Differentiation of aleurone cell layer already starts from near embryos. Nucellar cells are degenerating except for nucellar eidermis. Numerous endosperm cells are formed, having thin cell wall and small starch grains. After 4 days of anthesis, a primordium of coleoptile is initiated at the upper ventral side of embryos and an area of shoot apex can be identified. Vacuoles in the cells are numerously present in scutellat parenchyma and few in the vicinity of shoot apex. The suspensor cells and epidermal cells are clearly differentiated. Interestingly, scutellar epithelium arise in company with the collapse of cuticular layer already formed. Zygotic embryos and somatic embryos were partially compared. Regarding the underexploited plants, approximately 30 species were collected including Malva and Corchorus.