Structural and cytochemical analysis of female reproductive development in Ornithogalum sigmoideum Freyn & Sint

Abstract

In the present study, after the determination of karyological characteristics of Ornithogalum moideum, the development of female gametophyte, embryo and endosperm was investigated, and cytochemical features were identified. The diploid chromosome number is 16 in O. sigmoideum. The ovule is anatropous, bitegmic and crassinucellate. The ovular structures such as obturator and nucellar epidermis secrete insoluble polysaccharides, and play a role as the guidance and growth of the pollen tubes. The tissue differentiation called hypostase is located at the chalazal part of the ovule. This tissue is stained deeply with PAS, and it stores a large quantity of starch grains. The embryo sac development is Polygonum type. In the mature embryo sac, the egg cell and synergids are surrounded by a complete cell wall. The synergids show a similar polarization to the egg cell, and their cell walls form a prominent filiform apparatus at the base of cells. Cytoplasm of the egg cell is not rich in insoluble and acidic polysaccharides, proteins, and lipids whereas cytoplasm of the synergids and antipodals are rich in insoluble polysaccharides, proteins but is not rich acidic polysaccharides and lipids. The starch grains are peripherally located in the central cell. The embryo development is Asterad type. The endosperm is helobial.