Author: Tian Guo wei and Shen Jia-heng
J Integr Plant Biol 1993, 35 (5): 0-.
The ultracytochemical localization of ATPase activity was carried out employing the method of lead precipitation in the ovules of wheat(Triticum aestivum)before and during fertilization. Only very little ATPase activity was observed on the plasma membrane of the egg cell in the mature embryo sac before fertilization. At this stage, reaction product was localized primarily on the plasma membranes of two synergids, on the chalazal plasma membrane ,ER and tonoplast of the central cell, on the plasma membranes of the antipodal cells,some nucellar cells surrounding the embryo sac and the inner and outer integument cells. During fertilization, ATPase activity was found in the following places:the plasma membrane, nucleus and nucleolus of the egg cell;the plasma membrane and nucleolus of the persistent synergid and the plasma membrane of the degenerated synergid; the cytoplasm, nucleus and nucleolus of the central cell ; the sperm nucleus within the egg and central cells and the sperm nucleolus appeared in the fusion of the male and female nuclei; the submicropylar embryo sac wall. At the same time, reaction product deposited on the plasma membranes of the antipodal cells and inner and outer integument cells was significantly decreased. In zygote stage, heavy reaction product was localized in the nucleolus of the zygote and the chromatin and nucleolus of the free nuclei of the endosperm. A little enzyme activity was observed on the plasma membrane and ER of the zygote and in the mitochondria of the zygote and central cell. We suggest that the ATPase distribution pattern and its change in different developing stages was associated with the activation of the egg cell ,the movement of the sperm nucleus,the physiological state of the egg, zygote and sperm nucleus,and the nutritional pathway of the embryo sac.