Protein Kinase AtCIPK8 Enhances Salt Tolerance Of Transgenic Arabidopsis Thaliana

One of the major environmental problems facing plant growth today is salinization of the land.SOS pathway is the main pathway of salt tolerance,in which SOS1 is the main acting protein,which can transport excessive Na~+from plant cells through Na~+/H~+antiporter on the plasma membrane of cells.AtCIPK8 is a protein kinase that regulates plant responses to salt stress by activating At SOS1-mediated Na~+rejection.Its mutants are very sensitive to salt stress.However,it is not clear whether overexpression of AtCIPK8 gene can further enhance salt tolerance in plants.In this paper,yeast expression vector and plant expression vector of AtCIPK8 gene will be constructed to explore the action site of AtCIPK8 gene on At SOS1 through yeast interaction.The plant expression vector will be used to transform Arabidopsis thaliana and the homozygous overexpressed plants of AtCIPK8 gene will be screened out through the method of plant vector specific primers and gene expression level.The experimental results are as follows:AtCIPK8 gene is closely related to SOS2,which is regulated by SOS3.The yeast two-hybrid analysis showed that AtCIPK8 could not interact with SOS3(CBL4),but could interact with CBL10.The yeast functional complementarity experiment showed that AtCIPK8 alone could not regulate the activity of Atatsos1,but it could interact with AtCBL10to regulate the activity of Atatsos1 to enhance the salt tolerance of yeast mutants.AtCIPK8 overexpressed plants were constructed and salt tolerance was analyzed.The germination of transgenic and wild-type(WT)plants was significantly inhibited by Na Cl treatment,but the germination rate of transgenic Arabidopsis seeds under 100 m M Na Cl treatment was higher than that of wild-type.In soil experiments,the transgenic plants grew significantly higher than the wild type under 200 m M Na Cl treatment.Compared with the wild-type,the over-expressed AtCIPK8 plants had lower Na~+content and higher K~+content,resulting in higher K~+/Na~+ratio of transgenic plants under salt stress than wild-type plants.In addition,the oxidation degree of transgenic plants and wild-type plants increased under salt stress,but the accumulation of hydrogen peroxide(H2O2)and malondialdehyde(MDA)in transgenic plants expressing AtCIPK8 with Na Cl decreased compared with that of wild-type plants.These results suggest that AtCIPK8 promotes the growth of transgenic plants by regulating intracellular ion and reactive oxygen species(ROS)homeostasis,and AtCIPK8may be a candidate gene for the development of salt-tolerant crops.