The Cross Of Maize Seedlings At Low Temperature Induced Adaptation And Induced Expression Of The Establishment Of The Cam / Cambp Transgenic Tobacco System

We used maize seedlings (Zea mays L.) and tobacco (Nicotiana plumbaginjfolia L.) as material. In the first section, we have investigated cold- shock-induced chilling, drought, heat and salt stress resistance in maize seedlings. In the second section, by modifying the Ca~ and CaM levels, we have tried to establish the involvement of calcium messenger system in the cold-shock-induced cross adaptation. In the third section, we have tried to establish a transgenic tobacco system expression CaMICaMIBP genes, so that the others can use it to investigate the process of physiology and biochemistry which endonuclear and cytosolic calmodulin have taken part in. For the first part, we used maize(DaHuang and Qing No.3) seedlings as experimental material. Firstly, we had studied the effect of cold-shock on chilling stress, by calculating the survival percentage, we found short-term cold-shock could enhance chilling stress, and short-term cold-shock also enhance drought, heat and salt stresses of two varieties of maize seedlings. It has been confirmed that short- term cold-shock could induce cross adaptation in maize seedlings, Secondly, for validating our results, we measured the electrolyte leakage of maize roots and the cell vitality of maize coleoptiles, these results confirmed further that the phenomenon of cross adaptation exists in maize seedlings. Then we measured the acctivities of ascorbate peroxidase (APX), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD) and peroxidase (POX) of cold pretreatmented maize seedlings in the course of chilling, drought, heat and salt stress. We found that cold pretreatment enabled the seedlings to keep relatively higher activities of APX, GR, CAT, SOD and POX than control. These indicate that the improvement of stress tolerance is often related to the enhancement of activity of antioxidant enzyme system in plants. We also measured MDA content under chilling, drought, heat and salt stress. Under stress condition , MDA content increased, but cold-shock -5- could lower it. Finally, we probed into the role of hydroperoxide (H202), it seemed that H-,02 is the signal of environmental stress, and we can suggest that H202 initiated the process of cross adaptation. In the second section, we probed into involvement of calcuim messenger system in the cold-shock-induced cross adaption. In the former results, it indicated that Ca2~+-CaM have involved in the signal transduction for cold stress and the formation for cold resistant of plants. So we may coclude calcuim messenger system have invovled in the cold-shock-induced cross adaption. By modulating Ca2~+ and CaM levels which on the effect of chilling, drought, heat and salt stress, we have studied on the effect of the calcuim messenger system on the cold-shock- induced cross adaptation. In the last section, we used two verities of transformed tobacco (TetR2.3 and H02020) leaves as experimental material. The gene of CaM or CaMBP was transferred into leaf disks with the help of Ti-plasmid of agrobacterium tumeinfacien.s. Tobacco seeds were germinatted in MS medium containing Km. Leaf disks have been rooted in MS medium contain kanamycin and hygromycin or barsta after agroinfection, co-culture in 4---6 weeks. We have been established a transgenic tobacco system expressing calmodulin and calmodulin-binding peptide. Wee gotten more than 50 transgenic tobacco lines and we are selectting for the better lines.