Ecological Anatomy And Comparative Embryology Studies On Swertia Bimaculata (Sieb.et Zucc.) Hook.f.et Thoms.ex C.B.Clarke And Tripterospermum Discoideum (Marq.) H.Smith (Gentianaceae)

Swertia bimaculata ( Sieb.et Zucc. ) Hook.f.et Thoms.ex C.B.Clarke and Tripterospermum discoideum(Marq.)H.Smith are belong to Gentianaceae. Although their distributing areas and habitat are similar, their evolutionary trends and the way to utilize resource are poles apart in the area of Western Hunan. Ecological anatomy and comparative embryology of these two plants were studied which has definite theoretical and practical significance in understanding plant system and evolvement, the speciation, the adaptation origin, the conservation biology and so on. At the same time, as valuable Chinese traditional medicines, both of them are subject to serious intimidation. Up to now, the basic biological researches on ecological anatomy and comparative embryology of them are still blank. So this research can further enrich the base theoretical information about Swertia and Tripterospermum, and serve the protection, development and sustainable utilization of our traditional medical plants.1. Ecological AnatomyEach part of plant is mutual co-ordination to accomplish a certain physiological function. The results showed that S. bimaculata and T. discoideum in different habitats changed their anatomical structures of stem and blade to adjust the ecological environment. The changing of blade structure was the fastest and most evidential. In strong sunlight, the thickness of blade has increased to improve water retention ability; the ratio of palisade tissue and spongy tissue rose to improve the photosynthetic efficiency and reflect the strong light; the density of epidermal stoma also increased to enlarge the respiratory area. Not only did the structure of blade changed, but also the stem changed correspondingly, such as the thickness of cortex increased in strong sunlight so that the cortex can reduce evaporation and improve the photosynthetic efficiency. The well-developed pith is benefit for plants to keep and store water. In conclusion, the plants which live in strong sunlight, for one thing control the evaporation to reduce water loss, for another improve the photosynthetic efficiency.2. EmbryologyThe studies include the development of microsporangium, male gametophy, megasporogenesis, female gametophyte and embryogeny of S. bimaculata and T. discoideum.The main results of S. bimaculata can be concluded as follows: Anthers are tetrasporangiate. The development of anther walls conforms to the basic type and comprises of epidermis, endothecium, two middle layers and tapetum at the mature stage. The tapetum cells have dual origin and belong to the glandular type, for the anther locules have degenerating tapetum nuclei in the middle which are from the early dividing and intruding of the tapetum. Two middle layers are ephemeral; endothecium and epidermis persists and develops to become fibrous-thickening. The cytokinesis of the microspore mother cell in meiosis is of the simultaneous type. Most of the microspore tetrads are tetrahedral and there are still a few other types, such as isobilateral, dilateral . Pollen grains are 2-celled when shed. The ovary is bicarpellate, unilocular with 4 rows of ovules located at the parietal placentation. The ovule is unitegmic, enuinucellar and ana-campylotropous. The embryo sac originates from the single-archesporial cell. The one chalazal megaspore in linear tetrad becomes the functional megaspore. The development of embryo sac is the Polygonum type.Three antipodal cells have multiseriate nuclei and distinct haustorium, and persist like a layer of"outer endosperm"just out of the endosperm nucleus layer. Fertilization is porogamous and of premitotic syngamy type. The development of endosperm conforms to Nuclear type and the embryogeny corresponds to the Solanum type. The embryo is at the globular stage when seeds released from the capsule. The dividing and persisting of the antipodal cells in some annual Gentianaceous plants are of significance in reproductive adaptation and evolution. At the same time, comparative embryology among some species of Swertia was studied base on some recent data.This paper reports embryological characters of T. discoideum. The main results can be concluded as follows: Anthers are tetrasporangiate. The development of anther walls conforms to the Dicotyledonous type. The tapetal cells origin from the primary parietal cells, and thus the tapetum is of dual origin. The development of the tapetum with uninucleate cells is of the Glandular type. The tapetal cells on the connective side show radial elongation or periclinal division and intrude into the anther locule to form placenoids. The anther wall has only one middle layer; the endothecium persists and its cells become pillar and fibrous, and the epidermis degenerates. Cytokinesis at meiosis of microsporocytes is of the simultaneous type and most of microspore tetrads are tetrahedral, there are still a few other types, such as dilateral. Pollen grains are 2-celled. The ovary is bicarpellary and unilocular. The placentation is of reduced or typical parietal placentae with 4 rows of anatropus ovules that is unitegmic and enuinucellar. The one chalazal megaspore in linear tetrad becomes functional. The development of embryo sac is of the Polygonum type. Three antipodal cells persist. Flowers are protandrous. Fertilization is porogamous. The development of the endosperm is of the Nuclear type. The embryogeny corresponds to the Solanad type. The embryo is at the globular stage when seeds released from the capsule. At the same time, comparative embryology among some species of Tripterospermum was studied base on some recent data.3. Tissue cultureIn order to protect the natural resources of S. bimaculata and T.discoideum, which has been destroyed seriously, the method of artificial propagation by way of tissue culture have been systematically researched.The results of S. bimaculata: When the seeds that were on the initial phytohormone before grow into seedling, then take the stems, leaves and the stems with buds from seedling as explants, which are cultured on different culture media with the addition of different portions of various hormones at various cultural conditions. The stems were the best material in speeding propagation among the three explants (stems with buds, stems and leaves). The proper medium for the shoot differentiation was MS+ BA0.5mg/L + saccharose 3.0%, the optimum medium for proliferation was MS+BA 0.5mg/L+ IBA0.1mg/L+ saccharose 3.0%,and the best medium for rooting was 1/2MS+ NAA 0.5mg/L + saccharose 1.5%.The results of T. discoideum: The tissue culture and rapid proliferation techniques of T. discoideum were studied by using stems with buds, stems without buds and leaves as explants. The explants were cultivated in different MS medium with different types and concentrations of plant growth substances. The main results can be concluded as follows: the stems with buds were the best material in speeding propagation among the three explants. The shoot differentiation was MS+BA2.0mg/L+saccharose3.0%, the optimum medium for proliferation was MS+BA2.0mg/L+NAA0.1mg/L+ saccharose 3.0%,and best medium for rooting was 1/2MS+NAA0.5mg/L+saccharose1.5%.