磷酸酶ABI2在受体蛋白激酶FERONIA调控脱落酸与逆境响应中的分子机制研究

Studies of the molecular mechanisms how plants respond to the stress environmental signals are not only have great significance to plant science, but also an urgent question to answer for agriculture and forestry. We have found that FERONIA (FER) positively regulated the activity of ABI2 and inhibited the abscisic acid (ABA) response by way of small G protein signal pathway. We also found that fer mutants are sensitive to salt, cold and heat stress, but insensitive to osmotic stress. Based upon our previous work, this proposal is planning to resolve the following two scientific questions: (1) The molecular mechanisms that how FER regulates ABA response by using ABI2. The interaction of FER with ABI2 need be confirmed firstly. We then analyze whether phosphatase ABI2 can dephosphorylate kinase FER, or whether FER can regulate the activity of ABI2 directly. (2) The molecular mechanisms that how FER regulates abiotic stress response. This proposal will focus on the mechanisms of how FER controls these stress responses by using ABI2 and ROS signaling molecule. The research will assist us in obtaining overall knowledge of the FER signaling network, especially regarding ABA and stress responses. Taking into account the conservativeness of FER in plant kingdom, our work will also be of benefit to molecular breeding of stress-tolerant crop varieties.

植物对逆境响应的分子机制不仅是植物科学关注度极高的理论问题，也是农、林应用领域急需认识的问题。申请者已发现受体蛋白激酶FERONIA（FER）可通过GEF-ROP小G蛋白信号途径激活磷酸酶ABI2并负调控脱落酸（ABA）反应，另外FER突变体对盐、冷、热胁迫敏感，而对渗透胁迫耐受。在此基础上，本课题拟探讨以下两个科学问题：（1）FER通过ABI2调控ABA反应的精细分子机制。确认激酶FER能否与磷酸酶ABI2互作，并分析ABI2能否使FER去磷酸化，或FER能否直接调控ABI2的磷酸酶活性；（2）FER调控非生物逆境胁迫响应的分子机制，确认FER能否利用ABI2与活性氧（ROS）信号分子调控植物逆境响应过程。本研究旨在为全面了解FER的功能，特别是在ABA及逆境响应方面的功能，提供更深入的认识。鉴于FER在植物界的保守性，本研究结果将为耐逆农作物品种的分子育种提供一定参考。

植物的生长速率必须与环境信号协调。逆境下，植物体内ABA含量升高，植物生长速率减缓，目前对此过程的分子机制所知甚少。受体激酶FERONIA (FER) 是一个植物细胞生长的关键调节子，但是FER是否参与逆境调控尚不清楚，前期工作发现FER通过GEF1/4/10-ROP11激活ABI2从而抑制逆境激素ABA的响应。在本课题的资助下，利用受体激酶FER的多克隆抗体分析发现，FER的磷酸化水平受到RALF与ABA的上调，接着利用酵母双杂交筛选发现FER可以与磷酸酶ABI2互作，进一步的分析发现PP2CA家族中与ABA相关的多个PP2CA成员都可以与FER互作。磷酸酶ABI2使激酶FER去磷酸化，而且该去磷酸化过程通过PYL/PYR/RCAR-PP2CA信号模块以依赖于ABA的方式进行。RALF1突变体与FER类似，均对ABA敏感。发现RALF可以抑制ABA响应，而ABA可以激活RALF响应从而抑制植物生长，本课题研究结果揭示了RALF与ABA信号交叉会话的信号通路，提出了一个植物如何在逆境下平衡其生长速率的工作模型。