The Distribution Of ATPase During The Anther Development Of ALLIUM CEPA L.

ATPase is a kind of metabolic enzyme that decomposes ATP to provide energy. ATPase distribution is closely related to the cell special function which needs some energy. Therefore, the amount of ATPase accumulated in different parts of a cell can display the amount of ATP in this part, which can also reflect this metabolic strength occurring in the place. In this study, we investigated the dynamic distribution in the anther cells of onion (Allium cepa L.) during their development using ATPase-lead nitrate depositional method. The mechanism of anther development of onion will be better understood once the characters of anther development are linked together with ATPase distribution. The results as follows:During early anther development, few ATPase precipitates appeared in the cells of anther at the stage of microspore mother cells. When microspore mother cells divided, some ATPase precipitates were located in some organelles which mainly distributed in peripheral region of the cell during meiosis, while the central regions were occupied by chromosomes. There were still few ATPase precipitates in the tetrad microspores. Microspores of onion began to form the exine on its surface and some ATPase precipitates accumulated on the two sides of exine. ATPase precipitates did not increase at all in the cytoplasm of young microspore just released from the tetrad. Meanwhile the microspore began to synthesize its intine and many ATPase precipitates specifically accumulated in the intine. With the development of young microspore, the precipitates increased in its cytoplasm. At the same time, some small vacuoles fused with the intine of germ pore making it thickened and forming some tubular channels intermediate where a large number of ATPase precipitates located. No a large vacuole formed during the microspore development of onion. However the nucleus of microspore can still locate in the region in opposite germ pore, showing a kind of polar state. There were more ATPase precipitates in nucleolus and karyoplasm of microspore, and its cytoplasmic vesicles also contained some significant ATPase precipitates. The germ pore accumulated a lot of ATPase too, suggesting that the pore was a gate that the nutritional substances entered into microspore, and ATPase involved in this process. The polar microspore divided inequilaterally and formed a 2-cellular pollen grain after its mitosis. ATPase precipitates accumulated more in both nuclei of vegetative cell and generative cell but less in the cytoplasm. When the generative cell detached from the intine of pollen, abundant ATPase precipitates specially accumulated in the place where generative cell connected. With generative cell detaching from intine, abundant ATPase precipitates appeared in the region of intine where generative cell attached, suggesting more energy consumed during this process. When the generative cell was completely suspended in the cytoplasm of the vegetative cell, the precipitates on the wall of the generative cell entirely disappeared. With pollen development, the number of ATPase precipitates gradually increased in the vegetative cell but it did not happened in generative cell, which displayed a difference of ATPase precipitates both cells. The mature pollen of onion was 2-cellular, and in the cytoplasm of the vegetative cell scattered some tiny ATPase precipitates.The anther wall of onion was composed of four layers of cells, namely, epidermis, endothecium, middle layer and tapetum. At early stage of anther development, epidermis, endothecium, and middle layer became high vacuolization, and few ATPase precipitates were in their cytoplasm. However, there were some precipitates located on their plasma membranes, suggesting their function of transporting nutriment. The quantity of ATPase precipitates of tapetal cells was the highest in the cells of anther wall. The inner surface of tapetum also accumulated more ATPase precipitates than the outer side. The polar distribution of ATPase precipitates of tapetal cells indicated their primary function of transporting nutrition materiel into locule.During anther development, the ATPase precipitates in the plasma membrane, cytoplasm, the cell walls and cellular gap of the somatic cells in connective tissue also displayed some changes, which might reflect state of transporting material into anther. The nutrition materiel can be transported into the locule not only by symplast approach, but also by apoplast approach during anther development.