The Functional Characterization And Regulatory Mechanism Analysis Of Jasmonate Synthetic Gene OPR3 In Thermotolerance Of Arabidopsis And Wheat (Triticum Aestivum L.)

High temperature had an adverse effect on the crop production, and exogenous application of MeJA significantly improved plants thermotolerance. To further investigate the regulatory mechanism of Jasmonate involved in thermotolerance, we focused the research on the 12-OPDA reducase 3(OPR3) from Arabidopsis and wheat. The expression profile and the function of OPR3 in thermotolerance were analyzed. On the other hand, the regulatory mechanism of AtOPR3 in thermotolerance were preliminary analyzed. The main results of this thesis are as follows:1?First, we found that exogenous application of MeJA significantly improved Arabidopsis thermotolerance, while blocking Jasmonate biosynthesis in opr3 after heat stress decreased plant thermotolerance significantly. On the other hand, the thermotolerance of opr3 could be restored by exogenous application of MeJA(5?M) or by transgenic with pAtOPR3:AtOPR3. We also found that the mutants of other genes involved in JA synthesis and signaling such as lox3, jarl, coi showed significantly defect in thermotolerance.2?The deletion of HSE in the promoter of AtOPR3 results the decreased transcript after heat stress. On the other hand, the transcript of AtOPR3 was significantly repressed in hsfa1a/hsfa1b compared with WT, this result agreed with the promoter activity analysis. These results showed that AtOPR3 was regulated by the binding of HsfA1a and HsfA1b with HSE.3?The transcripts of AtDREB2A, AtDREB2B and AtHSFA3 were much lower in opr3 than in WT after heat stress. Also, the expression of AtHSP101 and AtHSP17.6 were also down-regulated in opr3 than in WT. The phenotype of decreased thermotolerance of opr3 can be recovered after overexpressed with 35S:DREB2A. On the other hand, the thermotolerance of dreb2a will be recovered after pretreated with MeJA. Based on these results, AtDREB2A may work downstream of AtOPR3.4?The wheat homologous gene of AtOPR3 was cloned and located on chromosome 7A. TaOPR3 was induced by high temperature in wheat seedlings and flags, especially after extended heat stress. On the other hand, the thermotolerance of opr3 plants overexpressed with TaOPR3 was improved. In conclusion, TaOPR3 was involved in wheat thermotolerance. Furthermore, exogenous application of MeJA significantly improved thermotolerance of wheat CS and TAM107 seedlings.