Anther and Ovule Development in Scrophularia valida L.

Embryology can provide useful information for determining taxonomic and phylogenetic relationships at the genus level. The aims of this research were to analysis of anther and gynoecium structure and the development of male and female gametophytes in Scrophularia valida the. Buds, in various developmental stages, were collected, fixed in FAA, preserved in ۷۰% ethanol, embedded in paraffin and sliced with a rotary microtome. Results showed that the microsporogenesis and male gametogenesis features of S. valida included bisporangiate anther, dicotyledonous-type of anther wall formation, secretory tapetum, simultaneous cytokinesis in pollen mother cells, tetrahedral and tetragonal microspore tetrads and two-celled mature pollen grains. The tapetal cells are mainly uninucleate, but some are binucleate. The nuclei of these cells is large, indicating their high metabolic activity. The mature pollen grains are spherical in the polar view, elliptic and oblong in the equatorial view and are tricolpated. Ovule is anatropous, unitegmic and tenuinucellate. A linear megaspores tetrad is observed and the functional megaspore is chalazal one. In the study, like many species of scrofulariaceae, the mature embryo sac is of the polygonum type, which is the most common type among angiosperms and is considered as a primary feature. Antipodal cells are persistent and their nuclei become merged. They are also able to form an embryo at the chalazal pole, which detects apogamy in the species. One of the unusual features of S. valida is formation of hypostase that occupy large part of the ovule. S. valida is a primitive species regarding of hypostase long-life due it has stable large hypostase in the mature embryo sac.

Keywords:

Microsporogenesis , Megasporogenesis , Pollen grain , Embryo sac