玉米EIN3转录因子调控对玉米螟抗性机理研究

玉米是重要的粮食作物，丁布类物质是玉米中的广谱抗虫化合物，而玉米如何调控丁布的合成以应对虫害胁迫尚缺乏深入研究。我们发现乙烯途径受阻转基因玉米（ETR1）增强了对玉米螟的抗性，且玉米螟诱导的丁布含量在ETR1玉米中高于野生型。通过基因表达、进化分析及原生质体转化技术，我们初步确定了乙烯信号途径核心转录因子EIN3，发现其负调控丁布的合成。我们拟使用酵母双杂交、ChIP-seq结合RNA-seq技术，获得EIN3调控的蛋白及基因网络，并通过免疫共沉淀技术及启动子激活GUS活性分析，解析EIN3调控丁布合成的生化机理。此外，我们将制备EIN3过表达和基因沉默的转基因玉米，与野生型玉米比较分析：1）丁布含量及挥发物释放的变化，2）对玉米螟抗性，3）田间和实验室条件下对玉米螟赤眼蜂的吸引力，进而从生化分子机理和化学生态学层面上剖析乙烯信号途径中转录因子EIN3如何调控玉米对玉米螟的直接和间接抗性。

Maize is an important grain crop and benzoxazinoids (Bxs) are the most important chemicals defensing against a broad range of herbivores in maize. Yet, little is known how maize regulates Bxs biosynthesis against herbivores. We created transgenic maize lines which are insensitive to ethylene (ETR1) and these plants showed increased defense against Ostrinia furnacalis, and Bxs induced by O. furnacalis is higher in the ETR1 lines than that in wild-type plants. By phylogenetic and expression analysis and protoplast transformation, we identified the candidate EIN3 gene in maize, which is the key regulator in ethylene signaling, and we found that it negatively regulates Bxs biosynthesis. In this project, we aim to identify proteins and genes regulated by EIN3 via yeast two-hybrid and chromatin-immunoprecipitation sequencing (ChIP-seq) methods. How the above-mentioned proteins and genes regulate Bxs will be investigated by Co-immunoprecipitation assays and promoter-GUS activity assays, respectively. We will further overexpress and down-regulate EIN3 in maize. Using wild-type and these transgenic maize, Bxs biosynthesis and volatile release and the performance of O. furnacalis will be determined, and the behavior of Trichogramma ostriniae in the lab and field condition will be analyzed. Taken together, this work will provide knowledge on the biochemical molecular mechanisms and chemical ecology of how EIN3 and ethylene signaling regulate direct and indirect defense response of maize against O. furnacalis.