Cytobiological Study On Female Sterility In Camptotheca Acuminata Decne., An Endemic Plant To China

Camptotheca acuminata Decne. a unique anticancer drug plants, is the only source of camptothecin and its derivatives extraction. The florets of C. acuminata are hermaphroditic, and its seeds have higher level of camptothecin, at the flowering stage, female organs were aborted, the fallen petal phenomenon is serious, reduce the fruit production in C. acuminate. In order to understand the period, morphological anatomy of the pistil abortion during female organs developing, in this paper, based on the key period investigation, the cell morphology and histochemistry of female organs sterility were studied, by compared calcium ion distribution during the abortion and normal pistil development, these offer not only the causes and mechanism but also the theory base of female abortion.1. The morphological Study on Female Sterility in Camptotheca acuminata Decne.Take anticancer drug plants of C. acuminate for research object, the morphological Study on female sterility with digital stered microscope has observed. The results showed that the florets of C. acuminata are hermaphroditic, and the all of stamens develop in normal. The stigmas have three shapes of superior stigma, half-inferior stigma, and inferior stigma. In the floret with superior stigma, the pistil developed in normal, and the style elongate with three-lobed and everted stigma, pistil fertility. In the floret with half-inferior stigma, the pistil has selectivity abortion, and the style elongate slowly with abnormal stigma. In the floret with inferior stigma, the style degenerate, and the stigma inside ovary don’t revealed, the ovule is depauperate, the morphology of ovary is thin-long and interior employ, pistil abortion.2. The cytology Study on Female Sterility in Camptotheca acuminata Decne.Based on morphological observation, paraffin sectioning was applied for the observation of development process of the florets in C. acuminata. In the floret with superior stigma, the embryo sac of the pistil was normally developed. In the floret with half-inferior stigma, the pistil has selectivity abortion, the part of ovary cells become vacuolization with the degenerated ovule and abnormal embryo sac. In the floret with inferior stigma, the cells of integument are depauperate, the megaspore mother cell can’t meiosis, and the ovule is depauperate and interior employ. A strictly corresponding relation was believed between the development of pistil and the different morphology of stigma on ovary, and the abortion of pistil began before or after the meiosis of megaspore mother cell, and the female sterility was one of internal causes of serious inflorescence abscission in C.amptotheca.The ultrastructure studies of female organs sterility in C. acuminate have shown that, in the floret with superior stigma, the cells of female organs normal development, stigma with papillae cells on the surface, style cells and ovule cells have many normal organelles, membrane structural integrity and normal nucleus; In the floret with half-inferior stigma, the development of cells in female organs is unmoral, the surface of the cell wall thickening, style cells and ovule cell apoptosis with characterized of shrinkage nucleus, condensation chromatin and marginalization, the cells is vacuole. Cell death of female organs in C. acuminata belongs to typical phenomenon of programmed cell death; the relationship between the caused of apoptosis factors and nutrition or Ca2+is closely, which needs further study.In order to prove the relationship between female organs in C. acuminata and lack of nutrients, paraffin sections and histochemistry is used to study the dynamic distribution of starch and protein on the female organs abortion process, the results show that:starch grains in the upper stigma cells and ovule cells always distributed, in meiosis of megasporocyte stage, the starch grains concentrated accumulation in the stigma internal cell, nucellus cells, chalazal region, placenta, and ovary inner wall cells, the starch grains is not accumulated in micropyle; In the stage of mature embryo sac formation, the stigma cell internal starch grains increased, a large number of starch granules accumulated in embryo sac. Less starch grains was distributed during the development of inferior stigma, the surface of stigma do not have papillary protrusions; In megasporocyte stage, almost no starch grains accumulation in ovule, including nucellar cells, chalazal end cells and ovary cells were not observed starch granules, the late development of ovule become disintegration with internal starch grains distribution, compared to the upper stigma ovule, the inferior stigma ovule cells protein staining were shallow. Lower stigma ovule starch grains and protein nutrients lack, is one of the important factors during meiosis of megasporocyte failed.3. Localization of Ca2+study on. Female Sterility in Camptotheca acuminata Decne.We observed the changes in distribution of calcium precipitates on female sterility in C. acuminate using ultrathin sections and antimonite precipitation of calcium method, combined with transmission electron microscopy, the results show: a large number of calcium particles distributed in the pistil stigma, style and ovule, stigma cell wall also have calcium, and the calcium increments gradient distribution during style upper to the lower part of the embryo; stigma, style and ovule of abortion pistil only a small amount of calcium particles distribution, there is, no significant gradient distribution in style cells, styles rely on the micropylar end cell apoptosis, calcium enriched in the cell membrane and organelle membrane cells, A large number of calcium particles in the cell gap. This indicates that the abnormal calcium distribution on Female Sterility in C. acuminate is closely related to calcium in cells re-distribution start or induced programmed death of cells, leading to the female organs structure was destroyed.