Structural Characteristics Of Heteromorphic Leaves And Influences On Leaf Development Under Tissue Cultural Condition Of Populus Euphratica

Populus euphratica Olive, one of tall arbors growing in salinized desert belt, is a most ancient, primitive tree of Salicaceae. It has great stress resistance, and its leaf shapes vary with the growing up of the tree. The leaves are lanceolate in early growth period, and then change into different shapes as oval, extravagant oval, broad triangular and dentate broad-ovate leaves. In this paper, the mechanism of the development of the leaves of Populus euphratica were studied through the observation of structure, tissue culture of stem and analysis of protein.1. The microstructure traits and ultrastructure traits of three kinds of typical leaves of populus euphratica including lanceolate, broad-ovate and dentate broad-ovate leaves were studied by using the techniques of electron microscope and light microscope in this paper. The result showed that from lanceolate to broad-ovate the leaves tended to be xeromorphic structure obviously. The main embodiments were developed palisade tissue, less spongy tissue, thicker cutin layer and sunken stoma, more mitochondrias. The shape of chloroplasts changed from regular spindle-shaped to irregular rotundity and oval. The number of stomas was approximate equal on the two sides of the leaves, and the stomas opened uniformly. The leaves surface was waxed covered without cilium, and the sunken stomas on the lower side of the leaves were deeper than those on the upper side of the leaves. The result indicated that the structure characteristics of the heteromorphism leaves of populus euphratica and their eco-adaptability were interrelated. In this paper we studied the influence of different concentrations of plant hormone on asexual reproduction of Populus euphratica, the influence of different concentrations of ions on etiolation, and the influence of salt stress and osmotic stress on leaf shape.2. The tissue culture system was set up through the study of the influencesof different phytohormone proportion on start, proliferation and differentiation culture of the stem of Populus euphratica. At the same time it is also studied that the function of different ion concentrations in solving the etiolation of the rootless seedling in tissue culture. The result of another research about the salt stress and water stress showed that the lanceolate leaves would vary to dentate lanceolate leaves under the condition of low salt tress but die under the high salt stress. It showed that thevariation of the leaves was related to the adaptation to the environment. 3. In this research, the protein analysis was carried out to study the leaves development of Populus euphratica. The result indicated that the species and content varied distinctly with the development of the leaves. There was obvious difference between young and old leaves in the same shape that there was a special protein of 56. 4kd. On the other side there was also differences between leaves in different shapes. It was found that there was a special protein of 64. 2kd. In the protein contrast with Salix matsudana Kolidz and Populus Canadensis Moench, the result showed that the protein of Salix matsudana was similar to the old leaves of P. euphratica and the Populus Canadensis was similar to the young leaves.