Changes of calcium distribution in ovules of Torenia fournieri during pollination and fertilization

Calcium distribution in ovules of Torenia fournieri was studied by electron energy loss spectroscopy and transmission electron microscopic visualizati on of calcium antimonate precipitates. High calcium levels were found in th e ovules of T. fournieri. Calcium is situated mainly in extracellular regio ns before fertilization, including the surface of embryo sac, in the mucila ge, and among the cells of the egg apparatus. Intracellular calcium was fou nd only in the nucellar cells around the embryo sac and in the epidermis of the central axis and funiculus. After pollination, a labyrinthine structur e (coralloid-like cell wall formation) develops on the micropylar surfaces of the egg apparatus that contain high levels of calcium. Calcium levels in crease in the degenerating synergid after the penetration of the pollen tub e. Calcium-antimonate precipitates are abundant in vacuoles of the disrupte d synergid and pollen tube cytoplasm.