ERF19和NINJA抑制複合體參與阿拉伯芥抗灰霉病的功能性分析

Abstract

植物在受到病原菌攻擊時會啟動免疫反應從而引起一系列免疫基因的表達。這個過程需要非常精細的轉錄水平上的重新編碼。舉例來說，乙烯調控因子在植物調節免疫反應中有著重要的作用。在我們實驗室之前的研究中發現，阿拉伯芥過表達ERF19基因時表現出比野生型更加容易被灰霉病菌感染的性狀。這種性狀是通過抑制免疫基因PDF1.2a以及PR3的表達所導致的。在我的研究中，構建了ERF19的功能缺失植株，發現它們表現出比野生型更加抗灰霉病菌感染的性狀。通過原生質體瞬時表達實驗發現ERF19是轉錄激活子而ERF19過表達植株中的免疫基因被抑制。於是我通過酵母雙雜交，蛋白質免疫共沉澱以及雙分子螢光光互補實驗發現ERF19蛋白可以和NINJA抑制複合體有交互作用。更有趣的是，在ninja突變體中過表達ERF19蛋白會嚴重改變阿拉伯芥的生長表型以及抗病表型。所有這些新的發現對於研究ERF轉錄因子參與植物免疫反應有嶄新的意義。

When attacked by pathogens, plants activate the immune responses to regulate the inducible expression of a large set of defense genes. This process requires effective transcriptional reprogramming. For example, ethylene responsive factor (ERF) transcription factors (TFs) have been shown to play critical roles in regulating immune responses in plants. In the Zimmerli laboratory, overexpression of ERF19 was shown to increase Arabidopsis susceptibility to Botrytis cinerea (B. cinerea) via repression of the induction of the jasmonic acid (JA) defense marker genes PDF1.2a and PR3. In this study, I generated pERF19:ERF19-EAR transgenic lines and these loss-of-function plants exhibited increased resistance to B. cinerea, when compared to wild type (WT) plants. ERF19 acted as a transcriptional activator, however defense genes were repressed in ERF19 overexpression lines. Using the yeast two hybrid, Co-IP and BiFC assays, ERF19 was shown to associate with the NINJA repressor complex. Moreover, overexpression of ERF19 in Arabidopsis ninja mutant strongly changes the developmental pattern and defense phenotype of the plant. Notably, a strong increased susceptibility to B. cinerea was observed. All these findings provide new insight on how ERF TFs regulate plant immunity.