| The London plane(Platanus acerifolia Willd), one of the world famous roadside trees, owns the merits of beautiful shape, dense shade, huge crown, tolerance to atmospheric pollution and resistance to smoke and dust. Besides, it is easy to cultivate, which gives the tree strong ability to adapt itself to the urban environment. However, in the end of spring and the beginning of summer in every year, the London plane has a serious problem with its dispersal of seeds and releasing of short, stiff hairs from leaves affect human’s normal life, which also in turn limit the application.We verified the hereditary stability of transgenic tobacco’s phenotypes through observing the phenotypes of the second generation of transgenic tobacco (T1); In order to obtain the sterile plant of Platanus acerifolia Wild, we constructed interference vectors of some flower development genes. Because of the long periods in getting transgenic plane plants, we transformed them into tobacco and observed the phenotypes instead. The main purpose of this study is to understand the molecular mechanism of the flower development, which will not only enrich the flowering theory of woody plants and diclinous plants, but also will provide reliable approach to breed transgenic plane trees that have no seeds nor seeds’ hairs. The major results are listed below:1. The methods of selecting the first generation of transgenic tobacco (T0) seeds are as follows:we sowed them on filter paper, and provided them fixed quantity of distiled water with kanamycin at the concentration of250mg/L on fixed time. It can be observed that the positive plants growed normally and the color of which is emerald after8days. On the other hand, the false positive plants’ color is yellow, they growed slowly, and later they would die gradually.2. To verify the hereditary stability of transgenic tobacco’s phenotypes, we observed the T1generation of transgenic tobacco plants and found that (1) the transformed35S::PaSEP1tobacco lines flowered about54days earlier, and they also had lower plant height, shorter internodal length, less and small leaves. The plants owned lateral branches too, which would grow into secondary flower branches later;(2) the transformed35S::PaSEP3tobacco lines had no different phenotypes from the wild tobacco except for the increasing number of flowers at full-bloom stage;(3) the transformed35S::PaFUL tobacco lines showed striking differences on the length of internodal distance and the number of leaves compared to the wild type;(4) the transformed35S::antiPaSEP1,35S::antiPaSEP3,35S::antiPaFUL tobacco lines shared same traits about vegetative growth, florescence and development of floral organ with wild type plants. All the phenotypes of these transgenic tobacco plants were in accord with their T1generation except for some small differences between transformed35S::PaSEP3,35S::PaFUL plants and their T1generations.3. After analysed the phenotypes of transformed35S::PaSEP1,35S::PaSEP3,35S::PaFUL tobacco’s T1generation, we come to the conclusions that the expression of exogenous genes in young flower bud and young leaves are positively correlated to the phenotypes, which means that the more obvious the phenotypes are, the higher quantity the exogenous gene expressed and vice versa. This conclusion demonstrated that dosage effect is existed in the expression of exogenous genes in plants. In other words, the higher quantity this exogenous gene expressed in transformed plants, the more obvious the phenotypes are and vice versa.4. Compared to wild type and their parents, the hybrid tobacco lines of35S::antiPaSEP1×35S::antiPaSEP3,35S::antiPaSEP3×35S::antiPaSEPl showed no significant differences.5. Through double transformation of AP3and PI genes from the London plane into tobacco, it can be observed that (1) the sepals of transformed35S::PaAP3-35S::PI2a lines were much longer and thinner than those of wild type, and the sepals were found to be in open state, the stigmas of pistil prolonged out of the stamen, the morphology of ovary changed into tubular, and the ovary expanded to the middle of pistil which made it looks like the pollen sac of stamen, petals and stamen were almost the same as those of the wide type;(2) transformed35S::PaAP3-35S::PI2b lines’sepals had more obvious crack and were much longer and thinner too, there were no differences between their petals, stamen and pistil and wild types;(3) transformed35S::PaAP3-35S::PI2c lines’ main four types of flower organs showed no significant differences compared to those of wild type.6. We have constructed the interference vectors of35S::PaFULi,35S::PaLFYi and dual interference vector of35S::PaLFY-FULi, and transformed these vectors into tobacco lines mediated by Agrobacterium. It can be found that:(1) transformed35S::PaLFYi,35S::PaLFY-FULi tobacco lines shared the same phenotypes, all of their plants were much higher and larger, they had much bigger ground diameter, longer internodal distance, more and larger leaves, and more flowers at full-bloom stage compared to those of wild type. It would not take too much time to form secondary flower branches after blossom, but their florescence was almost the same as wild types.(2) there were two different kinds of phenotype in transformed35S::PaFULi tobacco lines, one was that parts of flowers’corolla tube became shorter than those of wild type, and those flowers couldn’t produce seeds; the other was that sepals of flowers were relatively more compact and tenuous. |
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