Responses Of Physiological Mechanism And Proteins Associated With Photosystem In Thellungiella Halophila And Arabidopsis Thaliana Under Salt Stress

This dissertation aimed to compare and study physiological and molecular responses of salt cress (Thellungiella halophila) and Arabidopsis thaliana under salt stress. The main characteristics examined included the growth of the seedling, osmolytes solutes contents, K~+ and Na~+ concentrations, and antioxidant enzyme activities. The main results are summarized as follows. 1. The relative growth rates of salt cress were not inhibited under the 200 mM NaCl stress or less while those of A. thaliana were seriously inhibited. 2. The contents of osmolytes solutes and reactiveosygenspecies increased profoundly in salt cress. 3. Antioxidant enzymes increased faster in Salt cress than in Arabidopsis thaliana in the same concentration of salt stress and SOD,CAT,APX,POD have the same increase trends to eliminate ROS as a whole. 4. As NaCl increased from 0 to 200 mM, the concerntration of Na~+ increased gradually and K~+ decreased gradually in leaves of Arabidopsis thaliana, K~+/Na~+ decreases gradually; while under the same treatment, Na~+ change little and the concentration of K~+ and K~+/Na~+ increased firstly and decreased finally in leaves of Salt cress. The K~+/Na~+ of salt cress is as 2-5 times as that of Arabidopsis thaliana under 100 mM and 200 mM NaCl stress. Salt cress appears to have higher ability to resist salt through absorbing K~+ while excluding Na~+. 5. Photosystem subnits of Salt cress were bigger than that of Arabidopsis thaliana . 6. More photosystem proteins were synthesized in salt cress than in Arabidopsis thaliana. These findings indicate that the differences in salt tolerance between the two species may be due to subtle differences in the regulation of osmolytes solutes and antioxidant enzymes. Salt cress may improve its salt torelacne through increasing basical metabolization under salt stress.