The Effects Of Calciun And Calmodulin Antagonist On Chilling Resistance Of Pepper Seedling

Calcium is an essential nutrition element in the plant. Calcium can prevent injury and leakage of membrane.It play an important role in maintaining cell wall , cell membrane structure and function, as a second messenger within cells for improving the resistance of plants. The central link of its role is the changes of Ca²⁺ level intracellular. The function of calcium messenger system formed by Ca²⁺ and its receptor protein CaM in plants adversity signal feelings was paid much attention Since 1976 Calmodulin (CaM) is found. But mechanism of calcium in the cold resistance of plant is still unclear, and there are still many unknown areas to be studied. Pepper (Capsicum annuum L) originated from tropical regions of Central and South America, it is widely popular temperature-sensitive vegetables. Because it's major crop of winter cultivation, so it's cultivated area is expanding in China in recent years. The optimal growing temperature of Pepper is 20°C to 30°C, the growth stopped completely below 15°C. it may suffer consistently below 12°C , even it will dead below 5°C, so low-temperature is a major limiting factor during pepper cultivation. Therefore, raising the pepper seedling cold resistance has become a urgency on theoretical research and practical production. The study of cold resistance and chemical control of Pepper seedlings is of great significance.The low-temperature-sensitive crops -- pepper seedlings were used as material in the test, the effect of calcium and calmodulin antagonist on chilling of pepper seedlings was studied. The results are summarized below:1. Adequate calcium(10mmol/L) supply can improve the activity of superoxide dismutase (SOD), peroxidase (POD) in pepper seedlings leaves and remain them at a relatively high level. Moreover, reduce content of malondialdehyde (MDA) and membrane permeability. Additionally, the exogenous calcium enhances the root activity of pepper seedlings. This indicates: adequate supply of exogenous calcium(10mmol/L) is one of the reasons that raising Pepper cold resistance ,because it enhances the ability of aliminating active oxygen species (AOS) and maintenance of membrane stability 2. Extraneous calcium(10mmol/L) treatment could markedly increase the content of soluble protein, soluble sugar and proline. Moreover, addition of Ca²⁺ chelating agent EGTA or calmodulin antagonist W7 could markedly decrease the content of soluble protein, soluble sugar and proline. Taken together the above results, it is suggested that Ca²⁺ signal system may be regulated by change of some osmolytes in Pepper under low temperature.3. Seeds soaking with Ca(NO3)2 could increase significantly the activity of protective enzyme and content of protective substance, decrease electrolytic leakage, the content of MAD in pepper seedlings, therefore, improving the ability of cold resistance at low temperature.4. Seed soaking with Ca²⁺ solution obviously decreased the contents of malondialdehyde (MDA) and electrolyte leakage, increased the activities of superoxid dismutase (SOD), Peroxide enzyme (POD) and the content of soluble protein and soluble sugar of pepper leaves, seed soaking with W7 distinctly enhanced the contents of MDA and electrolyte leakage, reduced the activities of SOD, POD and the content of soluble protein and soluble sugar of pepper seedling leaves under chilling stress, The result suggests that Ca²⁺·CaM messenger system plays an important role in controlling chilling resistance of pepper seedling.