Mechanism Analysis Of AtPLC3 And AtPLC4 In Salt Stress Response Of Arabidopsis Thaliana

Response to salt stress signal transduction in plant is a huge and complex network, there are many key signal components to be deeply understood. Phosphatidylinositol-4, 5-bisphosphate-specific-phospholipase C (PIP2-PLC) is a lipid-associated enzyme which employs PIP2 to produce inositol-1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). These two messenger substances play crucial roles in amplifying extracellular stimuli and mediating various physiological processes caused by different abiotic stresses.In our initial research, We used the method of the reverse genetics to identify AtPLC3 and AtPLC4, two genes of the PLC family, to provide a in vivo evidence for which PLC regulate physiological responses under salt stree. In order to study the mechanism of PLC, we continue to use p3 and P4 mutants as experimental materials. The real time PCR results and the physiological analysis showed that AtPLC3 and AtPLC4 maybe participant in the signal pathway of salt stress through scavenging the reactie oxygen species.The main results were shown as follows:(1) The results of real time PCR showed that P4 mutant is AtPLC4 overexpression, OEPLC4 is AtPLC4 overexpression transgene line, PLC4RNAi is AtPLC4 RNA interference lines. The characteristics of the three lines shouwed,â‘ AtPLC4 was induced about 1.8-192 times by salt stress in different genetype of Arabidopsis thaliana, it suggests that AtPLC4 participant in the signal pathway of salt stress.â‘¡The results that the germination rate and the survival rate of P4 and OEPLC4 which AtPLC4 were overexpression were superior to WT, about higher 10%-38% than WT, while PLC4RNAi which AtPLC4 was suppression, has lower germination rate and survival rate than WT, about lower 10% than WT. These results suggest that AtPLC4 maybe a positive gene. We also observed the physiological indexes, the content of solubility sugar,proline,MDA and H₂O₂, the activity of SOD,POD,CAT,APX, these results showed that the content of proline,MDA and H₂O₂ of P4 and OEPLC4 were lower thanWT, while the content of proline,MDA and H₂O₂ of PLC4RNAi were higher than WT. the activity of SOD,POD,CAT,APX in P4 and OEPLC4 were higher than WT, the activity of SOD,POD, CAT,APX in PLC4RNAi were lower than WT. Many studies say that the content of proline,MDA and H₂O₂ were the signs of the injury of plasma membrane in plant. These results indicate that P4 and OEPLC4 have strong tolerant to salt stress, whereas PLC4RNAi is salt-sensitive. It suggests that AtPLC4 maybe improve the salt tolerance through scavenging the reactie oxygen species under salt stress.(2) p3 is AtPLC3 functional defect mutant, whose AtPLC4 was overexpression. OEPLC3 is AtPLC3 transgene line. The characteristics of physiological index showed that the phenotype of p3 was same as P4, whose germination rate and survival rate were higher than WT, the content of proline,MDA and H₂O₂ of p3 was lower than WT, while the activity of SOD,POD,CAT,APX in p3 was higher than WT; the phenotype of OEPLC3 was same as PLC4RNAi, whose germination rate and survival rate were lower than WT, the content of proline,MDA and H₂O₂ of OEPLC3 was higher than WT, while the activity of SOD,POD,CAT,APX in p3 was lower than WT. All these results showed that p3 has more salt tolerance than WT, while the salt tolerance of OEPLC3 is weaker than WT. These results indicate that AtPLC3 maybe a negative gene in salt signal pathway through scavenging the reactie oxygen species.