Effect Of Sodium Chloride On The Physiological Chararcteristics In Nitraria Tangutorum Bobr. Calli

Soil salinity, one of the most major adverse environmental factors, not only restricted plant growth and development, but also impaired crop productivity. Plants were jeopardized in some different ways, such as water deficit, oxidative injure and iron imbalance. Some plants had evolved a variety of physiological and biochemical processes to maintain a stable intracellular environment in the presence of salt stress. The mechanism of salinity tolerance in plants had been a hot issue, but efforts to make sure explicit mechanism under salinity had been elusive owing to its multigenic and quantitative nature. Nitraria tangutorum Bobr., a highly adversity-resistant halophyte, was regarded as the significant ecological security barrier in saline desert. The calli of it were employed to study the relationship between NaCl stress and changes of physiological characteristics. Further, the present study aimed at revealing the salinity tolerance mechanism of Nitraria tangutorum Bobr. at the cellular level, and providing the theory guidance for saline soil remediation and Nitraria tangutorum Bobr. exploitation. The main results were as follows:There was no change of malondialdehyde (MDA) content in Nitraria tangutorum Bobr. calli exposed to 75 mmol/L NaCl stress for 12 days, but 150 and 300 mmol/L NaCl brought significant increase in the amount of MDA. Compared to the control, NaCl stress induced increased activity of superoxide dismutase (SOD) in the calli. However, the activity of catalase (CAT) was firstly increasing, then decreasing with the enhance of NaCl concentration. In addition, no changes in peroxidase (POD) activity were observed in Nitraria tangutorum Bobr. calli, but 150 and 300 mmol/L NaCl brought significant decrease in the POD activity. With the addition of NaCl concentration, the amounts of soluble sugars and soluble proteins in Nitraria tangutorum Bobr. calli increased firstly and then decreased.75 mmol/L NaCl elevated sodium (Na) and chlorine (Cl) level in Nitraria tangutorum Bobr. calli, while weakened potassium (K) and calcium (Ca) content. Accordingly, the ratio of Na+/K+ and Na+/Ca2+ was improved with time extension. In addition, the amount of proline was accumulated in NaCl concentration-dependent manner at the same treatment time. Under the same density of NaCl stress, proline level in Nitraria tangutorum Bobr. calli increased firstly then decreased. There was equal proline content between the control group and 75 mmol/L NaCl-treatment group for 9 days but higher proline level was observed in other salt stressed groups. Further study showed that proline accumulation in Nitraria tangutorum Bobr. calli induced by NaCl stress was reversed by adding DMTU.These results suggested that:â—‹1 Nitraria tangutorum Bobr. calli demonstrated higher activity of antioxidase and the stronger effect of osmotic regulations under lower concentration of salty stress, nevertheless, the higher NaCl concentration caused obviously oxidated damage.â—‹2 75 mmol/L NaCl induced Na and Cl level increased in Nitraria tangutorum Bobr. calli, but resulted in K and Ca content decreased. Also, proline played a significant role in salt stress.â—‹3 Endogenesis H2O2 might participate in the modulation of proline in Nitraria tangutorum Bobr. calli.