DEVELOPMENT OF THE SEED OF SOLANUM PHUREJA

Dnyansagab , Vishnu R., and Delmer C. Cooper . (U. Wisconsin, Madison.) Development of the seed of Solanum phureja. Amer. Jour. Bot. 47(3) : 176—186. Illus. 1960.—Ontogeny of the seed of Solanum phureja Juz. et Buk. is described. The megagametophyte, during the course of its development, ruptures the nucellus and at maturity lies in direct contact with the inner layer (endothelium) of the single massive integument. The mature megagametophyte, a 7-celled structure, consists of a 3-celled egg apparatus, an endosperm mother cell with fused polar nuclei and 3 persistent antipodals. Both 2- and 3-celled mature pollen grains are formed within anthers of the same flower; hence this character cannot be considered of any taxonomic value. Double fertilization occurs between 24 and 72 hr. after pollination. A cellular endosperm is formed, the peripheral layer acting as an absorbing tissue during the early ontogeny of the seed. Later this layer becomes organized as an aleurone layer and thereafter the source of nutrients is via the basal portion of the endosperm immediately adjacent to the apical end of the vascular tissue of the developing seed. Embryo development follows the Nicotiana variation of the Solanad type. The mature testa is composed of an outer layer of thick-walled epidermal cells, an inner layer of thin-walled cells and an intervening mass of disorganized tissue. In those instances where the ovule or young seed aborts, the endothelial cells of the integument become hyperactive and proliferate to such an extent that the space formerly occupied by the gametophyte or the developing endosperm and embryo becomes completely filled with endothelial tissue.