核桃多酚调节因子JrTTG2调控干旱胁迫响应的功能机理研究

核桃是重要的木本油料植物，含有极高的与逆境响应密切相关的多酚类物质。但迄今关于核桃逆境适应机制方面的研究鲜见报道，特别是多酚调控基因的抗逆机制尚未见报道。WRKY是植物逆境响应中一类非常重要的转录因子，其中TTG2亚类与多酚合成调控相关。在前期研究中，我们发现核桃多酚调节因子TTG2基因（JrTTG2）能被干旱显著诱导，且可能参与干旱响应。在此基础上，本研究将获得JrTTG2基因的过表达和抑制表达核桃株系，研究其抗旱能力及对下游防卫反应基因的表达调控。用表达谱芯片技术比较转JrTTG2基因核桃与野生核桃的基因表达差异，确定JrTTG2调控的下游靶基因及抗逆调控途径；用染色质免疫共沉淀（ChIP）、酵母单杂交等技术鉴定JrTTG2识别的DNA及顺式作用元件，分析JrTTG2对下游靶基因的转录激活强度。通过这些研究阐明JrTTG2基因的抗旱功能及调控机理，为揭示核桃的逆境适应机制奠定基础。

Juglans regia is an important woody oil plant that contains extremely high polyphenols, which are closely related to stress response. However, there were few studies on adaptation mechanism of walnut tree to biotic and abiotic stress conditions, especial the stress resistance molecular mechanism of polyphenol regulatory genes has not been reported yet. WRKY is a very important transcription factor family in plant stress response, in which TTG2 subclass is involved in the regulation of polyphenol synthesis. In previous study, we obtained a polyphenol regulatory TTG2-like gene from J. regia (JrTTG2) that could be significantly induced by drought stress, and may participate in drought stress response. In this study, we will construct overexpression and RNAi-silence vector of JrTTG2 gene and transformed them into wild type J. regia, respectively, then the functions on drought resistance and regulation to the downstream defence genes will be clarified. The expression differences of downstream target genes among overexpression, RNAi-silence and WT walnut plants will be compared by chip technology, the downstream target genes regulated by JrTTG2 and the regulatory networks they participated in will be determined. The DNA and cis-acting elements recognized by JrTTG2 will be identified using chromatin immune coprecipitation (ChIP) and yeast one-hybrid assays; meanwhile, the transcriptional activation activity of JrTTG2 to the downstream genes will be illustrated; then the functional mechanism of drought regulation of JrTTG2 gene will be elucidated. This study will not only generate a foundation for further studying the adaptation mechanism to adverse stimulus, but also provide strong support for developing new suitable varieties of J. regia.