Structural and Functional Study of Protein Post-Translational Modifications involved in Plant Stress Signaling

干旱、洪水、盐碱或极端温度等非生物胁迫会严重降低主要农作物的产量，随着气候变化的影响变得更加明显，这些损失正在增加。植物在分子水平上通过触发信号通路来响应非生物胁迫，从而导致众多基因的表达发生变化，从而使植物适应新的环境。泛素化和SUMO化是两种翻译后修饰，泛素或SUMO(小泛素样修饰物)蛋白与靶蛋白共价连接，在这些途径的调控中发挥着重要作用。然而，它们如何在分子水平上运作仍然是相当难以捉摸的。我的研究计划的主要目标是从结构和功能上表征参与植物对非生物胁迫反应的泛素化和SUMO化事件的分子决定因素，以便能够合理地设计或选择更具抗逆性的植物突变体。为了实现这一目标，将解决以下三个具体目标：*1.确定与植物非生物胁迫反应有关的特定和有效的SUMO化事件的分子决定因素。*2.通过表征赤霉素信号通路中特定的翻译后修饰事件，在分子水平上确定植物如何平衡生长和胁迫反应。赤霉素是一类植物生长调节剂，也参与植物胁迫反应。*3.通过模式生物拟南芥的功能分析，了解选定的个体和集体E3-底物相互作用对植物非生物胁迫反应的贡献。*我们的研究计划将产生一个框架，在分子水平上理解植物逆境反应中涉及的相互作用，特别是翻译后修饰，因为这些修饰可以快速重塑整个反应途径。这应该有助于设计或选择对非生物胁迫具有更高耐受性的植物。赤霉素和苏莫化途径的突变体已经成为作物改良的诱人目标。我们获得的结构信息将进一步允许以非常有针对性和可调的方式对农学有用的植物进行基因工程。此外，分子决定因素的识别及其在应激反应中被证实的作用，将有助于预测基因组群体中自然变异的影响。然后，可以通过标记辅助育种策略来分离这些变异，并将构成转基因植物商业开发的替代方案。因此，在全球农业面临的压力随着世界人口增加、农业面积缩小和重大气候变化而稳步增加的背景下，我们的研究计划应该会为加拿大农业带来重要好处。**

Abiotic stresses, such as drought, flood, salinity or extreme temperatures, can severely reduce the yield of major agricultural crops, and these losses are increasing as the effects of climate change become more pronounced. Plants respond to abiotic stresses at the molecular level by triggering signaling pathways that lead to changes in the expression of numerous genes to allow plants to acclimate to their new environment. Ubiquitination and SUMOylation, two post-translational modifications where Ubiquitin or SUMO (Small Ubiquitin-like Modifier) proteins are covalently attached to target proteins, are increasingly recognized as playing a prominent role in the modulation of these pathways. However, how they operate at the molecular level remains quite elusive. The overarching goal of my research program is to structurally and functionally characterize the molecular determinants of Ubiquitination and SUMOylation events involved in plant response to abiotic stresses so that better stress-resilient plant mutants can be rationally designed or selected. Towards this goal, the three following specific objectives will be addressed:******1. Identify the molecular determinants of specific and validated SUMOylation events involved in plant abiotic stress response.***2. Determine how plants balance growth and stress responses at the molecular level by characterizing specific post-translational modification events in the signaling pathway of gibberellins, a family of plant growth regulators that are also involved in plant stress response.***3. Understand the contribution of selected individual and collective E3-substrate interactions to plant abiotic stress response through functional analyses in the model organism Arabidopsis thaliana.******In doing so, our research program will generate a framework for understanding interactions involved in plant stress response at the molecular level, with a special interest for post-translational modifications, as these can rapidly remodel entire response pathways. This should facilitate the design or selection of plants with increased tolerance to abiotic stress. Mutants of the gibberellin and SUMOylation pathways are already attractive targets for crop improvement. Our gained structural information will further allow genetic engineering of agronomically useful plants in a very targeted and tunable manner. Also, the identification of the molecular determinants and their validated role in stress response, will help predict the effects of natural variations in genomic populations. Such variants could then be isolated through marker-assisted breeding strategies and would constitute an alternative to the commercial development of transgenic plants. Our research program should thus provide important benefits to Canadian agriculture in a context where pressure on global agriculture steadily increases with increasing world population, shrinking agricultural area, and significant climate change. **