泛素连接酶MxRHEL参与MPK4-Fd3途径调控苹果砧木缺铁胁迫信号的机制研究

铁是植物生长必需的微量元素，研究苹果砧木的耐缺铁机理具有重要意义。之前研究显示，活性氧(ROS)作为信号通过MAPK通路开启胁迫应激反应，其中磷酸激酶MxMPK4除激活下游通路外，还可调控铁氧还蛋白MxFd3反馈作用于ROS产生。进一步，我们挖掘到与MxMPK4互作的新E3泛素连接酶MxRHEL。基于以上基础，本研究将以耐缺铁材料小金海棠为试材，通过蛋白修饰及转基因手段确定MxRHEL与MxMPK4的交互应答关系，探究MxRHEL对MPK4-Fd3过程的调控作用及对缺铁响应的影响；并研究三者组成的调控路径对缺铁胁迫下ROS信号通路的反馈调节作用；最后根据RHEL在不同耐缺铁特性砧木中的序列差异，探究RHEL差异与MPK4-Fd3的关系及对砧木耐缺铁特性的影响。本研究期望阐明一条缺铁胁迫信号产生的反馈调节通路，明确不同耐缺铁特性苹果砧木应答响应的差别，为探究苹果砧木耐缺铁机制提供理论依据。

Iron is an essential micronutrient required for plant growth. It is significant to reveal the resistance mechanism of iron deficiency of apple rootstocks in apple production and rootstock breeding. Studies on iron-efficient apple rootstocks have shown that Reactive oxygen species (ROS) initiate stress response through MAPK cascade system as a signal. In addition to activating the downstream pathway, phosphokinase MxMPK4 also feedback acts the production of ROS by regulating ferredoxin MxFd3. Furthermore, we discovered a new E3 ubiquitin ligase interacting with MxMPK4, named MxRHEL. Based on the above, this study will determine the cross-talk interaction between MxRHEL and MxMPK4 by phosphorylation, ubiquitination and transgenic methods, and explore the regulatory effect of MxRHEL on MPK4-Fd3 process under iron deficiency and its effect on the stress response, using Malus xiaojinensis as test material. Then study the feedback regulation to ROS signaling pathway under Iron deficiency by MxRHEL, MxMPK4 and MxFd3 pathway through exogenous reagents treatment. Finally, rootstocks with different iron deficiency tolerance characteristics will be used to study the relationship between RHEL sequence difference and MPK4-Fd3 process, thus affecting the iron deficiency tolerance of rootstocks. In the end, we hope to elucidate a feedback regulation pathway of iron deficiency signal, clarify the difference of response in apple rootstocks with different iron deficiency tolerance characteristics, and provide theoretical basis for exploring the mechanism of iron deficiency tolerance of apple rootstocks.