| Vegetative Storage Proteins(VSPs), as a stored nitrogen compounds, play an important role in the growth, flowering, fruiting and in the resistance of tree to environmental stress. The distribution and seasonal changes of vegetative storage proteins in branchlets and small roots of Ginkgo biloba L., which was especial a rare species in China, were investigated by light- and electron microscope and SDS-PAGE techniques in the dissertation. On the basis, the main vegetative storage proteins in Ginkgo biloba L. were identified by western-blotting, indirect immunohistochemical localization and colloidal gold labelling techniques. The main conclusions were as follows:(1)The vegetative storage proteins were stored mainly in the secondary phloem parenchyma cells of branchlets and small roots. Besides, they were found in the cortex parenchyma cells and secondary xylem ray cells of branchlets, and also in the secondary xylem ray cells and secondary xylem parenchyma cells of small roots, but almost not in cambium cells.(2)The vegetative storage proteins were synthesized in cytoplasm and then accumulated in vacuole with different forms such as floccular,granular,conglobate and homogeneous. In the initial stage, the storage proteins were accumulated in large central vacuoles mainly with forms of floccular and homogeneous, while accumulated in numerous small vacuoles with other forms in dormant stage. Different forms often presented in different cells other than in the same cells.(3)The seasonal change of vegetative storage proteins of Ginkgo biloba L. was obvious. The process of change could be divided into two stages which called degradation and accumulation. In the dormant period, the bark and xylem of branchlets accumulated abundance vegetative storage proteins. The content of proteins in annual shoots was higher than that of biennial branches. Moreover, the content of proteins in bark was higher than that of xylem. These proteins degraded gradually in the process of bud germination, and disappeared completely after new shoots sprouting. The degraded proteins provided important source of nitrogen to the growth of new shoots. In mid-May, the new shoots started to accumulate vegetative storage proteins with the growth of new shoots and leaves mature. The vegetative storage proteins began to be accumulated rapidly during leaf fall period, whose content ammounted the most in December. The dynamic change of vegetative storage proteins in roots was similar to that of branches. But, the beginning of degradation time of proteins in roots was earlier than that of branches, and the great accumulation in roots began later than that of branches. Moreover, the accumulation in roots was not as rich as in branches. The process of dynamic change in roots may be related to the growth activities of itself.(4) The seasonal change pattern of vegetative storage proteins in Ginkgo biloba L.was characterized by being mobilized with being reaccumulating. The new shoots could accumulate vegetative storage proteins early.(5) Two kinds of relative high content proteins with molecular weights of 36kDa and 32kDa were isolated and purified from the bark tissue of annual shoots by SDS-PAGE technique. The polyclonal antibodies of the two proteins were obtained successfully from New Zealand white rabbits immunized respectively by the two proteins. Western-blotting analysis showed that 36kDa and 32kDa had the common epitopes. Indirect immunohistochemical localization and colloidal gold labelling had proved that 36kDa and 32kDa proteins were the main components of the vacuolar protein inclusions of the protein-storing cells. It was obvious that they met the three standards of vegetative storage protein in woody plant developed by Clausen and Apel. The 36kDa and 32kDa proteins was proved to be the main vegetative storage proteins of Ginkgo biloba L.. |
