Function Of CIPK8 Gene Under Low Temperature,Salt And Drought Stress In Tomato

Tomato（Solanum lycopersicum）is a worldwide economic crop,which plays an important role in global vegetable cultivation.As the largest planting area with the highest yield of Tomato in the world,China also suffered from various stress in tomato cultivation,cold stress,salinity stress,drought stress etc.These abiotic stresses could result in serious damage to tomato,and thus quality degradation even complete yield loss.Calcium is a ubiquitous second messenger in plant,which plays an important role in intracellular signal transduction.Calcium signal is sensed by several calcium regulated protein sensors.Calcineurin B-like proteins（CBL）protein,as one of the protein sensors,participates in various stress responses by cooperating with CBL binding protein kinases（CIPKs）.CBLs-CIPKs signal pathway shows diversity,specificity and complexity under different stresses,which is regulated by complex intracellular mechanisms.It has been found that CBLs-CIPKs signal pathway plays an important role in response to abiotic stress.However,the function of SlCIPK8 in low temperature,salt and drought stress has not been studied in tomato.This study is of great significance to understand the function of SlCIPK8 under low temperature,salt and drought stress.The main results are as follows:（1）SlCIPK8 located on chromosome 5.The length of SlCIPK8 gene is 1356 bp.SlCIPK8 protein is composed of 451 amino acids with molecular weight of 51.3 k Da,14 introns and isoelectric point of 7.69.The protein was predicted to be hydrophilic and non-transmembrane,with 65 phosphorylation sites.（2）The psupermyc1300-GFP-SlCIPK8 vector was constructed.The psupermyc1300-GFP-SlCIPK8plasmid was transiently transformed into tobacco by Agrobacterium gv3101,and the SlCIPK8 protein was located on the cell membrane.（3）The expression of SlCIPK8 in tissues was analyzed by q RT-PCR.The results showed a high expression level of SlCIPK8 in leaves,stems and roots.（4）The psupermyc1300-SlCIPK8 vector was transformed into Tomato by Agrobacterium tumefaciens,and the transgenic plants with overexpression of SlCIPK8 were gained.The transgenic accessions were screened and identified,and the OE-7,OE-14 and OE-15 accessions with high expression level were chosen for subsequent experiments from the whole transgenic accessions after screening and identification.（5）The transgenic accessions and wild-type plants were treated by low temperature stress.After 12hours of low temperature stress,the leaf curl of wild-type tomato was more obvious than that of SlCIPK8transgenic tomato.The CAT activity of SlCIPK8-overexpressed transgenic tomato was extremely significantly higher than that of wild-type Tomato under the entire cold treatment period.（6）The transgenic accessions and wild-type plants were treated with salinity stress respectively.After 9 hours’s salt treatment,the stem of wild-type tomatoes wilted,while the stem of SlCIPK8-overexpressed transgenic tomato was still straight.The contents of SOD,free proline and soluble sugar in SlCIPK8-overexpressed transgenic tomato were significantly higher than those in wild-type plants,and the contents of O^2-in SlCIPK8-overexpressed transgenic tomato were significantly lower than that of wild-type plants.（7）The transgenic accessions and wild-type plants were treated with drought stress.After 9 hours of drought treatment,the stem of wild-type plants could not stand upright,and the leaves of transgenic accessions overexpressing SlCIPK8 wilted and remained upright.The contents of SOD,pod,free proline and soluble sugar in transgenic tomato plants with SlCIPK8 overexpression were significantly higher than those in wild-type plants,and the O₂^-content of overexpression plants were significantly lower than that of wild-type plants.In this study,SlCIPK8 was analyzed in detail by bioinformatics for the first time,and the alterations of SlCIPK8 under abiotic stress of low temperature,salt and drought were systematically investigated.The physiological indexes of SlCIPK8 overexpression transgenic accessions and wild-type plants under stress conditions were detected,and the expression of stress-related genes was measured.The results showed that SlCIPK8 transgenic accessions have strong resistance to drought,followed by salt and low temperature,which provided a certain basis for the cultivation of tomato resistance to abiotic stress.