Mechanisms of nutrient sensing and homeostasis in plants

植物生长需要光、二氧化碳、水和矿物质营养。虽然阳光和二氧化碳通常充足，但水和矿物质营养素往往是植物生长的限制因素，使灌溉和肥料成为作物生产和可持续农业的两种最昂贵的投入。然而，依赖化肥并不是一个长期的解决办法，因为化肥的生产和使用都会造成污染，威胁到我们环境的可持续性。另一种策略是培育具有高养分利用效率的作物，但这需要了解植物如何获得和利用每种养分，这就是本研究项目的主题。该项目的发现将通过与PI实验室相关的国际和美国农业部实验室的持续合作应用于作物改良。这项研究将通过PI在加州大学伯克利分校教授的课程以及PI实验室的独立研究项目对本科生和研究生教育产生额外的影响。该项目还将加强以当地高中为重点的外联工作，鼓励代表性不足群体的学生对生物学感兴趣。该项目将支持多样性，扩大弱势个人的参与，包括支持一名残疾研究人员。膜转运对于植物细胞和整个植物水平的矿质营养平衡具有重要意义。为了茁壮成长，植物已经进化出复杂的机制，在细胞和整个植物水平上保持矿物质的体内平衡，尽管土壤中的营养状况不断变化。PI的实验室发现了钙反应模块（CBL-CIPK），形成了营养传感的信号网络。新的研究结果表明，植物还利用保守的营养传感器，目标的RAPAMYCIN（TOR），整合高钾（K）营养状态，启动“生长模式”，并通过降解CBL-CIPK模块抑制低钾反应。低钾诱导的CBL-CIPK网络的激活以相互作用的方式抑制TOR活性并将植物切换到“适应模式”，从而建立了植物如何适应土壤中不断变化的营养状况的概念框架。相同的CBL-CIPK网络激活螯合镁（Mg）进入液泡响应高镁，提供了一个可能的机制，整合不同的营养线索。最近发现的镁转运蛋白负责镁螯合进入（和再动员出）的液泡设置的阶段，连接CBL-CIPK模块的镁转运蛋白，构建一个分子中继从高镁状态的蛇纹石土壤（信号），激活CBL-CIPK模块（信号），镁螯合进入液泡（响应）。本项目的具体目标是：1.明确低钾状态激活CBL-CIPK双通路的机制; 2.鉴定导致K诱导的TOR激活和CBL-CIPK网络失活的事件;和3.剖析控制Mg通过液泡膜的CBL-CIPK途径。该研究将受益于PI团队在模型植物系统方面的独特专业知识，这些系统适合于膜片钳和细胞生物学分析，并结合遗传和生物化学方法。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Plants require light, carbon dioxide, water, and mineral nutrients to grow. While sunlight and carbon dioxide are usually plentiful, water and mineral nutrients are often limiting factors for plant growth, making irrigation and fertilizers the two most costly inputs for crop production and sustainable agriculture. However, reliance on fertilizers is not a long-term solution because both production and application of fertilizers cause pollution and threaten the sustainability of our environment. An alternative strategy is to breed crops with high nutrient use efficiency, but this requires understanding how plants acquire and utilize each nutrient, which is the subject of this research project. Discoveries from the project will be applied to crop improvement through ongoing collaborations with international and USDA labs associated with the PI’s laboratory. The research will have an additional impact on undergraduate and graduate education through courses the PI teaches at UC Berkeley and through independent research programs in the PI’s laboratory. The project will also enhance the outreach efforts that focus on local high schools to encourage students of underrepresented groups to become interested in biology. The project will support diversity and broaden participation of disadvantaged individuals, including support of one researcher with a disability. Membrane transport is important for mineral nutrient homeostasis at the cell and whole plant level. To thrive, plants have evolved intricate mechanisms that maintain mineral homeostasis at the cellular and whole-plant level despite constantly changing nutrient status in soil. The PI’s lab discovered the calcium response modules (CBL-CIPK) that form a signaling network for nutrient sensing. New results indicate that plants also utilize a conserved nutrient sensor, TARGET OF RAPAMYCIN (TOR), to integrate the high potassium (K) nutrient status to initiate “growth mode” and suppress the low-K response by degrading the CBL-CIPK modules. In a reciprocal manner, low-K-induced activation of CBL-CIPK network represses TOR activity and switch plants to “adaptation mode”, establishing a conceptual framework on how plants adapt to the changing nutrient status in the soil. The same CBL-CIPK network activates sequestration of magnesium (Mg) into vacuole in response to high-Mg, providing a possible mechanism for integrating different nutrients cues. The recent discovery of Mg-transporters responsible for Mg-sequestration into (and remobilization out of) the vacuole set the stage for connecting the CBL-CIPK modules to the Mg-transporters, constructing a molecular relay from high Mg status in the serpentine soils (the signal), to the activation of CBL-CIPK modules (the signaling), and Mg sequestration into the vacuole (the response). The specific objectives of this project are: 1. To identify the mechanisms by which the dual CBL-CIPK pathways are activated by low-K status; 2. To identify the events leading to K-induced activation of TOR and inactivation of CBL-CIPK network; and 3. To dissect the CBL-CIPK pathway that governs Mg fluxes across the tonoplast. The research will benefit from the unique expertise of PI’s group in the model plant systems that are amenable to patch-clamp and cell biology analysis in combination with genetic and biochemical approaches.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.