Sporogenesis and gametophytes development in Datura stramonium L. (Solanaceae)

Abstract

Datura stramonium L., belonging to Solanaceae, is a medicinal plant with bioremediation potency that has variable characters and problematic taxonomy. The present study provides additional information on embryological characters in the D. stramonium that can provide useful information about the taxonomic of this species. The information is important for understanding the sexual reproduction process of this medicinal plant and also its phylogenetic position. The embryological properties, including sporogenesis and gametophyte development, of D. stramonium were examined by light, stereo, fluorescence and scanning electron microscopes. Results showed that each flower contained 5–6 tetrasporangiated stamens. The microsporogenesis and male gametogenesis characters of D. stramonium included dicotyledonous-type of anther wall formation, bi-nucleated and secretory tapetal cells, simultaneous cytokinesis in pollen mother cells, tetrahedral and tetragonal microspore tetrads and two-celled mature pollen grains. Ovary is formed by two carpels and contained numerous ovules with axile placentation. The anatropous, tenuinucellate and unitegmic ovules contained three archesporial cells. Only a single chalazal megaspore of the linear tetrad is functional. Polygonum-type embryo sac development, the presence of an endothelium, fusion of three antipodal cells and then formation of embryo without fertilization and cellular endosperm formation are the most important features in D. stramonium. The present findings reveal valuable developmental features can be used to discriminate this medicinal and environmentally important species and its phylogenetic relationships within the family Solanaceae.