SUB-CELLULAR DISTRIBUTION OF NUTRIENT ELEMENTS AND PHOTOSYNTHESIS PERFORMANCE IN ORYZA SATIVA L. SEEDLINGS UNDER SALT STRESS

In our study we focus on effects of multiple concentrations of NaCl (25, 50, 100, and 150 mM) on rice seedlings. The results showed that significant oxidation stress was caused, as indicated by the content of malondialdehyde (MDA). Na accumulation increased, and the vast majority of the ions were laied in the cell wall and these nutrient ions in the cell wall fraction were elevated, while those stored in the soluble or organelle fraction were declined. Meanwhile, the levels of photosynthetic pigments in leaves of 812HS decreased markedly. These fmdings were confirmed by the reduced photosynthesis. At 150 mM salt concentrations resulted in a significant damage to chloroplast structure. The data from the protein immunoblot assay revealed that salt stress affected the stability of protein. The major subunits of LHC II were more sensitive than reaction center proteins of PSII under solt stress. All together, these results showed that high salt concentrations disordered the ions homeostasis, stimulated reactive oxygen accumulation and lipid peroxidation in rice, leading to seriously damage to chloroplast ultra-structure, pigments and protein. Thereby, photosynthesis was inevitably blocked. This study is significant for comprehending the physiological and biochemical process under salt stress, and is important for devoting to organic agriculture in soil.