PtMPK7和PtMPK15基因在杨树响应对羟基苯甲酸胁迫中的调控机制解析

The declined land capacity of continuous cropping plantation is a worldwide problem, which seriously affects the sustainable management of plantation. To date, the molecular mechanism of continuous cropping plantation productivity decline of Populus is not clear. Our previous study revealed that the PtMPK7/15 genes participate in the Populus stress responses caused by p-hydroxybenzoic acid (pHBA), a principal component of allelochemicals in Populus. In this research, Populus trichocarpa is to be used to reveal the roles of Populus PtMPK7/15 genes in regulating the root development and stress responses caused by pHBA using gene over-expression and knock out strategy. In addition, the genes relating to root development and stress responses which are regulated by PtMPK7/15 will be analyzed by transcriptome sequencing of transgenic plants. Moreover, we will attempt to further elucidate the regulation mechanism of PtMPK7/15 in response to pHBA stress by identifying the upstream signal component that interacts with PtMPK7/15. This study will make an exploration on the new regulatory function of plant MAPK cascades and provide more theoretical surpport to overcome continuous cropping obstacle of Populus by genetic breeding strategy.

连作人工林地力衰退是一个世界性的问题，已经严重影响到人工林的可持续经营。目前关于杨树人工林生产力衰退的分子生物学机制尚不清楚。对羟基苯甲酸（pHBA）是杨树化感物质的主成分，我们前期研究发现PtMPK7/15基因参与杨树响应pHBA胁迫过程。本项目拟以毛果杨（Populus trichocarpa）为材料，通过在毛果杨中过量表达和敲除PtMPK7/15基因，分析PtMPK7/15在pHBA胁迫下杨树根生长发育过程和杨树响应pHBA胁迫过程中的作用；通过对转基因植株进行转录组测序，找出受PtMPK7/15调控的根发育相关基因和抗逆相关基因；同时，筛选、鉴定PtMPK7/15的上游互作子，从而阐明PtMPK7/15级联途径在调控杨树pHBA胁迫信号转导中的作用机制。本研究是对植物MAPK级联途径新的调控功能的探索，可为通过遗传育种途径克服杨树连作障碍提供重要的分子生物学基础。

连作人工林地力衰退是一个世界性的问题，已经严重影响到人工林的可持续经营。目前关于人工林生产力衰退的分子生物学机制尚不清楚。对羟基苯甲酸（pHBA）是杨树化感物质的主成分，尚无关于MAPK信号系统响应pHBA胁迫的报道。. 本项目首次克隆并鉴定了欧美杨（Populus × euramericana）的C组MAPK基因PeMPK7和D组MAPK基因PeMPK15，利用遗传学、分子生物学、生物信息学、生理学技术解析了其在杨树响应pHBA胁迫中的调控机制。（1）PeMPK7和PeMPK15的表达响应包括pHBA在内的多种非生物胁迫；（2）pHBA诱导的PeMPK7和PeMPK15表达依赖于内源活性氧信号；（3）遗传学分析证明PeMPK7和PeMPK15均具有正向调控杨树应答pHBA胁迫的作用；（4）过量表达PeMPK7和PeMPK15能够通过增强杨树的ROS稳态调节能力和渗透平衡调节能力，进而提高杨树对pHBA胁迫的耐受性；（5）通过野生型杨树的多组学联合分析揭示了杨树响应pHBA胁迫的化感响应机制；（6）通过比较转录组学和生理学分析揭示了PeMPK7调控的下游调控网络和光合作用适应机制；（7）蛋白互作分析鉴定到PeMPK7与PeMKK3直接互作、PeMPK15与PeMPKK7直接互作。. 研究成果对深入了解杨树的pHBA化感响应机制具有理论价值，对科学指导林木分子育种解决连作障碍具有实践价值。