由Lonsdalea quercina引起的欧美杨溃疡病于2006年在国内首次发现，不同于水泡型与冰核细菌型溃疡病，该病害对欧美杨速生林造成毁灭性破坏和严重经济损失，但其致病机制尚不明确。前期鉴定到一个参与氧化和渗透压胁迫应答与致病过程的双组分系统调节蛋白RRT1。RRT1的C端具有DNA结合域，推测其以转录调控方式参与信号网络调节。为了深入解析RRT1作用机制，本项目拟利用转录组学和分子遗传学等方法，在胁迫与非胁迫条件下，鉴定和确认RRT1直接转录调控的靶标基因及其互作蛋白。充分利用异源表达和缺失突变的分析方法，研究这些生物分子在病原菌的胁迫适应和致病过程中的功能，明确它们在信号网络中的地位。研究结果将揭示RRT1介导的信号调控网络在L. quercina生长、逆境胁迫应答及致病过程中的分子机制，同时对筛选以该网络关键信号分子为靶标的农用抗生素、设计高效低毒林木细菌病害控制策略提供指导。

A new canker disease of Populus × euramericana caused by Lonsdalea quercina subsp. Populi was first discovered in China in 2006. The disease causes much more devastating damage and severely economic loss to poplar plants than other types of poplar canker diseases. We have known nothing about the pathogenesis of this phytobacteria. In the latest study, we identified and characterized a regulation protein of two-component systems, RRT1, which is involved in responses to oxidative and osmotic stresses and virulence in L. quercina. RRT1 probably function as a transcription factor, since it has a C-terminal DNA-binding domain. The regulatory mechanism and the targets of RRT1 involved in these processes need to be explored. In this study, comparative transcriptomic and molecular genetic methods will be employed to identify the differential expression target genes of transcription factor RRT1 treated with or without oxidative and osmotic stresses; and proteomic techniques will be furthered adopted to identify the binding proteins of RRT1 under normal or stress conditions mentioned above. The interactions between candidate binding proteins and RRT1 will be confirmed by bacterial two-hybrid system, pull-down or MST. The confirmed candidate targets and binding proteins of RRT1 will be furthered investigated, as well as their effects on stress responses and pathogenicity of L. quercina by heterogenous expression, knock-out or knock-in mutation analysis. The results will propose a regulatory network mediated by RRT1 to address the mechanisms on growth and development, stress responses and virulence of L. quercina. This study will not only help us better understand the regulatory mechanisms of RRT1-mediated signaling network and screen for antibiotic drug targets, but also help to design efficient disease management strategies for poplar trees.