Induced Expression Of Cell Regulation Of Cam On Tobacco Resistance Effect And Its Physiological And Biochemical Mechanisms

Based on the versatile functions of CaM in plants, we had constructed four series tetracycline of (Tc)-inducible CaM/CaMBP transgenic tobacco systems to further study the function of CaM and the relationship between CaM and plant resistance, antioxidant enzyme and so on. The present research results included three parts: For the first part, we measured the CaM activity of 16 transgenic tobacco lines by Improved quantitative assay of plant calmodulin by phosphodiesterase. We selected 5 good transgenic tobacco lines(1C, 2C, 8C, 4L and7L) whose the activity of the reporter CaM increase up to 30-45% in seedlings as well as under greenhouse condition after treatment of transgenic tobacco with Tc .We firmed that 24 hours is the optimum Tc-inducible time from the curve of CaM activity during Tc-inducible 48 hours.For the second part, we used the five transgenic tobacco lines as experimental material. Under heat and chilling stress, the plant resistance of Tc-inducible CaM expression transgenic tobacco seedlings (or leaf disks) is strengthener than without Tc-inducible seedlings(or leaf disks) by electrolyte leakage and vitality of seedlings(or leaf disks). These results confirmed that Ca-CaM messenger system is involved in the tobacco heat and chilling resistance.In addition, we measured the activity of superoxide dismutase (SOD), glutathione reductase (GR), guaiacol peroxidase (GPX), catalase (CAT)and ascorbate peroxidase (APX) of leaf disks of the five transgenic tobacco lines. Under heat and chilling stress, the result of the plant antioxidant enzyme activity was cooperative the results of the plant resistance. However, under greenhouse condition, comparing the antioxidant enzyme activity of theTc-inducible CaM expression transgenic tobacco and without Tc-inducible, the former was higher . So we might conclude that Tc-inducible CaM expression enhanced the plant resistance, in fact, the reason is that CaM enhanced the five antioxidant enzyme activity.For the last part, we used Tc-inducible CaM expression transgenic tobacco (2C) leaf disks as experimental material. Based on the former results, we measured the changing of CaM and GR activity of 2C leaf disks in the Tc-inducible course and analyzed GR gene expression by semi-RT PCR. We found that CaM ,GR activity and GR gene expression of Tc-inducible transgenic tobacco was strengthener than those without Tc-inducible, and the transgenic tobacco without Tc-inducible was strengthener than the control (HO2020). These results could demonstrated that CaM might regulate GR gene expression.