Analysis Of The Resistance Of ZmSK1 And ZmCPP2 Transgenic Tobacco

As a steroidal plant hormone,Bassinosteroid(BR),not only functions in the growth and development but also regulates the plant response to various stresses.BR can enhance stress tolerance via regulating the antioxidant defense system.BIN2,a negative regulator in BR signaling,belongs to the Glycogen Synthase Kinase 3(GSK3)family.Recently,it has been shown that GSK3s played a vital role in response to various biotic and abiotic stresses.Our previous studies found that ZmSK1,a member of GSK3 family,is involved in BR-induced antioxidant defense system.ZmSK1 interacting with ZmCPP2 function in this process.Thus,we generate the transgenic tobacco plants of ZmSKl and ZmCPP2,then performe the stress tolerance.The results are as follows:1.The transgenic tobacco of ZmSKl and ZmCPP2 were successfully constructed and obtained by Agrobacterium-mediated genetic transformation.2.The germination of ZmSK1 over-expression seeds were slower compared to the control in the normal,drought and salt stress condition.Compared with the control group,the activities of antioxidant enzymes(APX and SOD)decreased 18.34%and 29.25%respectively,and the relative water content of leaves was 16.14%lower of mutants under drought stress condition.The electrolyte leakage rate of the ZmSKl over-expression leaves increased to 1.66-fold,and control group increased to 1.09-fold under the condition of drought stress.Under salt stress,the activities of antioxidant enzymes(APX and SOD)were 43.38%and 36.00%lower,and the relative water content of leaves was 46.51%lower of the ZmSKl over-expression leaves than control.The rate of electrolyte leakage of mutants increased to 3.80-fold,and control group increased to 3.09-fold.Under the condition of drought stress,ZmCPP2 over-expression of tobacco seed germination shortened 1 d.Compared with control group,the activities of antioxidant enzymes(APX and SOD)were 43.85%and 21.67%higher,the relative water content of mutants leaves was 36.91%higher,and the rate of electrolyte leakage was 10.37%lower of the ZmCPP2 over-expressed plant leaves.Under salt stress,the activities of antioxidant enzymes(APX and SOD)were 38.86%and 71.44%higher,the relative water content of mutants leaves was 18.17%higher,and the rate of electrolyte leakage decreased 17.55%of the ZmCPP2 over-expressed plants than control.These results showed that ZmSKl over-expressed plants were sensitive to stress signals.The sensitivity of ZmCPP2 mutant plants to stress was decreased,indicating that ZmCPP2 could enhance plant tolerance to stress.2.The average height,leaf area,leaf length and the sixth internode length of ZmSK1 transgenic tobacco plants were 21.46%,38.18%,13.04%and 33.00%lower than control group,respectively.The diameter of the stem was 23.08%higher,the leaf number is 3?5 more than wild type.Over-expression of ZmSK1 significantly affects the plant growth and development.