玉米EREB58转录因子能够调控萜类合成酶基因TPS10的表达,启动玉米抗虫间接防御体系。但是目前对于EREB58的转录调控机制还是未知。克隆得到EREB58基因的1 193 bp的启动子序列,通过生物信息学分析发现在启动子序列中存在多个与植物防御相关的顺式作用元件,如ABRE、Box-W1、GARE motif和TCA元件。将不同长度5’端缺失的启动子与GUS报告基因相连构建植物表达载体转化拟南芥,转基因拟南芥进行GUS组织化学染色和GUS酶活性分析,结果显示:正常情况下EREB58PF1-PF7和PF9无GUS染色,但PF8有GUS染色;Me JA或亚洲玉米螟处理后PF1-PF7有GUS染色,PF8无明显变化,PF9仍无GUS染色。GUS酶活性分析与GUS组织化学染色结果一致。以上结果表明:EREB58启动子的-323至-270和-270至-183区段是启动子的功能区段,且-323至-273区段含有抑制EREB58基因转录的顺式作用元件,-273至-183区段是EREB58基因转录所必需的,这为后续研究EREB58的转录调控机制奠定基础。
It was found that EREB58 transcription factor could regulate the expression of maize terpene synthase gene TPS10 and initiate indirect defense system. But the transcriptional regulation mechanism of EREB58 is still unknown at present. In this study,1 193 bp promoter sequence of Zm EREB58 was cloned and analyzed by applying bioinformatics. There were several cis-elements in the promoter,which related to plant defense,such as ABRE,BoxW1,GARE motif and TCA elements. The results of GUS histochemical staining and GUS enzyme activity analysis in transgenic Arabidopsis harboring different truncated Zm EREB58 promoter-GUS showed that under normal conditions,EREB58PF1-PF7 and PF9 were not stained,but PF8 was. After treatment with methyl jasmonate and Asian corn borer,PF1-PF7 were stained,PF8 without significant changes and PF9 still had no GUS staining. The analysis of GUS enzyme activity was consistent with the results of GUS histochemical staining. The above results indicated that the regions from-323 to-270 and-270 to-183 of the Zm EREB58 promoter were key sequences for performing promoter function. The region from-323 to-270 of the Zm EREB58 promoter contained cis-acting element inhibiting Zm EREB58 transcription; in the meantime the region from-270 to-183 of the Zm EREB58 promoter was integral for transcription. These results laid foundation for further studied on the mechanism of EREB58 transcriptional regulation.