玉米热激转录因子基因ZmHSF-Like对逆境胁迫响应的信号途径

在前期对玉米热激转录因子基因ZmHSF-Like克隆、表达特性和亚细胞定位分析的基础上,对基因响应不同逆境胁迫的信号途径进行了研究。结果显示,H2O2处理能显著上调ZmHSF-Like基因的表达,42℃热激上调ZmHSF-Like基因的表达依赖于H2O2的存在,ABA上调基因表达部分依赖于H2O2的存在,而PEG-6000诱导基因表达不依赖于H2O2;外源Ca2+处理也能上调ZmHSF-Like基因表达,而螯合胞外钙离子并阻断其内流并不能降低上述逆境胁迫诱导的ZmHSF-Like基因的表达水平。表明ZmHSF-Like基因通过H2O2信号途径实现对热激和ABA胁迫的响应。在H2O2处理过程中,热激蛋白基因HSP704的表达与ZmHSF-Like基因的表达同步,可能是该途径中ZmHSF-Like结合的下游热激蛋白。单独钙离子诱导处理,热激蛋白基因HSP701、HSP702和HSPeu701的表达均与ZmHSF-Like基因的表达同步,可能是ZmHSF-Like基因响应Ca2+反应的下游结合蛋白。ZmHSF-Like通过与下游不同热激蛋白的结合实现对不同逆境胁迫的响应。

Signal Transduction Pathway of ZmHSF-Like Gene Responding to Different Abiotic Stresses

Based on our previous findings of cloning, expression characteristics and subcellular-location of gene ZmHSF-Like, We analyzed the signal transduction pathway responding to different abiotic stresses. The results showed that the relative expression of gene ZmHSF-Like was up-regulated by H₂O₂. Up-regulating gene expression by heat shock of 42 ºC was dependent on existence of H₂O₂, while that PEG-6000 treatment was not. Up-regulating gene expression with ABA was partially dependent on H₂O₂. The relative expression of gene ZmHSF-Like was up-regulated by Ca²⁺ too, and chelating Ca²⁺ with methyleneglycol-bis- (2-aminoethylether)-N,N,N´,N´-tetraacetic acid (EGTA) and blocking Ca²⁺ intracellular transport with verapamil (Vp) did not decrease gene expression up-regulated by heat shock, PEG and ABA treatments. Those results illustrated that ZmHSF-Like realizes the response to heat shock and ABA through H₂O₂ signal transduction pathway. While treated with H₂O₂, the HSP704 gene expression was synchronous with that of ZmHSF-Like gene, HSP704might be the downstream binding protein of ZmHSF-Like in this signal transduction pathway. HSP701, HSP702, and HSPeu701 had the synchronous gene expression with that of ZmHSF-Like gene after Ca²⁺ treatment, suggesting that they are the downstream binding proteins of ZmHSF-Likeresponding to Ca²⁺. Those results further indicated that ZmHSF-Like makes response to different stresses through binding different HSPs.