Studies On Fruit Development And Somatic Embryogenesis Of Xanthoceras Sorbifolia Bunge

Shiny leaf yellowhorn, as an andromonoecious tree species, belongs to the genus Xanthoceras, the family Sapindaceae, and it is one of indigenous oleaginous and afforestation plants in North China. It is also very valuable in medical use or as an ornamental plant, which has important economic value. In this paper directing towards the"thousands flowers to one fruit"characteristic of shiny leaf yellowhorn we try to find out the cause and make the process of zygotic embryo development clear. Meantime, the somatic embryogenesis and development induced by tissue culture were investigated in shiny leaf yellowhorn. It can improve the understand to the mechanism of somatic embryogenesis and give us more good suggestions to get higher frequency regeneration system of superior tree. The main experimental results are as follows:1. The pollination characteristics, the regulation of fruit dropping, the development regulation of fruit and zygote embryo in shiny leaf yellowhorn were studied by the way of artifical pollination and paraffin slice. The result showed: Shiny leaf yellowhorn is a cross-pollination plant, and artifical pollination can increase fruit setting rate greatly. The first time of fruit dropping is happened after florescence two weeks later, which may be caused by fertilization failure. The second time of fruit dropping is happened after florescence one month later, which may be mainly caused by nutrition competition among fruits, and the global embryo is the most important period of nutrition competition. The seed embryo later development experiences several typical periods, including globular embryo, heart-shaped embryo, cotyledon embryo, in which starch and protain change regularly in different periods.2. Somatic embryo was induced by tissue culture using seed embryo, and the result showed: Basic medium B5 is better than MS in inducing callus. The concentration of 6-BA must be controlled in the low level, not higher than 0.5mg/L, otherwise it is very easy to cause callus browning, even death. Plenty of root-like is induced when just 2,4-D is used in callus subculture, but plenty of bud-like is induced when suiltable concentration of 6-BA is added in continuous subculture. NAA induces roots easily, but instead of 2,4-D in subculture it will reduce the effect time of 2,4-D. ABA can inhibit the division and growth of cells, using which can conrol the progress of somatic embryogenesis.3. Buds were induced directly by tissue culture using seed embryo as material, and the result showed: The effect of basic medium MS is better than that of B5 and 6-BA is necessary in inducing buds.