Influence On The Plant Growth And Correlative Gene Expression Under Stresses

Plants and their environment, which depend and interact on each other, are always considered as an integrated system. Nowadays, the effect of environmental factors on the growth of plants has become one of the hottest topics in plant physiology and biological physics. However, the researches available now on how plants respond the stress and how these signals lead to the expression of plant genes are not satisfactory enough. For the purpose of further exploring the influence of stress on the growth of cells theoretically and finding a new way to breed and improve new plant varieties in application, this paper studies the impact of the stress on the growth of plants on three different levels, i.e. organism, tissue, and cell, respectively, with the method of engineering. Meanwhile, the expression of plant genes under the stress on the genetic level is analyzed. The main contents and the results of the research are as follows.To begin with, the fundamental rule of the influence of sound wave stimulation on chrysanthemum seedlings is examined. The results show that chrysanthemum seedlings get the most obvious promotion under the frequency of 1000Hz and the intensity of 100dB, and over these values the promotion decreases. When a certain spectrum is reached, the opposite outcome is expected, that is, the growth of chrysanthemum seedlings would be inhibited. The growth rate increases when the frequency and the intensity are suitable. Investigation reveals that sound wave does not have an apparent influence on the normal photosynthesis and respiration of plants, which indicates that photosynthesis and respiration are not involved in the effects of the sound wave on plants. Then the vigor of root and the changes in the contents of the soluble sugar and proteins are surveyed. The results suggest that the vigor of root and the contents of soluble sugar and proteins are higher in the stimulated group than those in the contrastive group, thus implying that the appropriate intensity of sound wave would advance the growth of plants by enhancing the vigor of root and improving the absorption of nutritional elements. Meanwhile, protective enzymes of chrysanthemum are explored with chrysanthemum seedlings treated by sound wave with a certain intensity (100db) and frequency (1000 Hz). The results demonstrate that the activities of superoxide dismutase (SOD), peroxides (POD) and catalase (CAT) increase at varying degrees, and that better promotion for chrysanthemum is obtained under sound wave for 9 days. Furthermore, the activities of POD and CAT decrease correspondingly when CHM of different concentration, a kind of protein synthetic inhibitor, is added to the culture medium of the stimulated group. This means that the increase of the activities of protective enzymes is caused by the enzyme synthesis in plant cells which is advanced by the sound wave processing.Secondly, researches are done over the influence of the sound wave stimulation on the callus, and particular investigation is devoted to the changes in the contents of Endogenous Hormone indole-3-acetic acid (IAA) and abscisic acid (ABA). It is noted that sound wave plays a positive role in the growth of callus. Compared with the contrastive group, in the process of callus redifferentiation,the stimulated group gets obvious increase in the contents of IAA and some decrease in the contents of ABA. During this process, physiological function of the callus is enhanced or gene is expressed by the sound wave stimulation.Thirdly, the effects of sound wave on plasmalemma are studied. The results demonstrate that sound wave lowers the fluorescent polarization of DPH, while increasing the fluorescent intensity of MC540. It proves that under the sound wave stimulation of certain intensity the vesicles get looser, and both the charge density on membrane surface and the plasmalemma hydrophobicity decrease, however, the membrane fluidity increases. The secondary structure of protein plays an important role in carrying out the protein's function. In the present research, infr...