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最昂贵的两种投入。然而，依赖化肥并不是长久之计，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。另一种策略是培育养分利用效率高的作物，但这需要了解植物如何获取和利用每种养分，这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。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，这项研究将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推广工作，以鼓励代表性不足的群体的学生对生物学产生兴趣。该项目将支持多样化和扩大弱势群体的参与，包括支持一名残疾研究人员。在细胞和整个植物水平上，膜运输对矿物质营养平衡至关重要。为了茁壮成长，植物进化出复杂的机制来维持细胞和整个植物水平的矿物质平衡，尽管土壤中的营养状况不断变化。PI的实验室发现了钙响应模块（CBL-CIPK），它形成了一个营养感知信号网络。新的研究结果表明，植物还利用一种保守的营养传感器RAPAMYCIN （TOR）来整合高钾(K)营养状态，启动“生长模式”，并通过降解CBL-CIPK模块来抑制低钾响应。低钾诱导的CBL-CIPK网络的激活以相互的方式抑制TOR活性，将植物切换到“适应模式”，从而建立了植物如何适应土壤养分状况变化的概念框架。同样的CBL-CIPK网络激活镁（Mg）的封存到液泡中以响应高镁，为整合不同的营养线索提供了可能的机制。最近发现的镁转运体负责将镁固存到液泡中（并从液泡中再活化出来），这为将CBL-CIPK模块与镁转运体连接起来奠定了基础，构建了一条从蛇状土壤中高镁状态（信号）到CBL-CIPK模块的激活（信号），再到镁固存到液泡中（反应）的分子中继。本项目的具体目标是：1。确定低钾状态激活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在细胞质中的通量的CBL-CIPK通路。该研究将受益于PI小组在模式植物系统方面的独特专业知识，该系统适用于膜片钳和细胞生物学分析，结合遗传和生化方法。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

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.