Regulation of nutrient homeostasis by the CBL-CIPK calcium-based sensor-kinase network in plants

为了生长，植物需要平衡的矿物质营养供应，但今天的土壤往往缺乏必要的矿物质，如氮、磷和钾。为了克服这一不足，美国的作物生产严重依赖化肥的使用，但这种做法成本高昂，危及环境健康，而且不可持续，因为一些基本矿物(如钾肥和磷矿)是有限的自然资源。另一种更可持续的农业策略是培育具有新特性的植物，使它们能够在养分失衡的土壤中生长。要实现这一目标，需要更好地了解允许植物对土壤中不断变化的矿质养分状态做出反应和适应的分子网络。该项目通过研究当土壤中特定矿物质含量过多或过少时，植物如何维持矿物质营养的适当平衡来满足这一需要，从而为培育几乎不需要化肥的作物建立知识库，从而支持可持续农业。该项目将产生教育效益，为本科生和研究生提供从事研究的机会，并通过讲习班和其他旨在提高对生物学研究的兴趣的活动，接触到高中生，包括那些来自代表人数不足的群体的学生。植物通过控制跨质膜(用于吸收)和液泡膜(用于储存)的离子运输，不断监测土壤中的营养状况并维持营养动态平衡。然而，将土壤中的营养状态与植物的膜运输联系起来的信号机制在很大程度上还不清楚。首席研究员的实验室发现了CBL-CIPK钙信号网络，它在包括营养感知在内的许多细胞途径中发挥功能。除了针对低钾状态下的电压门控钾通道的CBL-CIPK通路外，他们最近的研究进一步发现了一个复杂的CBL-CIPK网络，该网络调节许多矿物营养物质的液泡运输。因此，这些发现将CBL-CIPK信号机制与植物细胞中两个最重要的营养动态平衡部位--质膜和液泡膜的运输活性的调节联系在一起。这项拟议的研究将检验一个主要的假设，即一个大型的“CBL-CIPK-离子通道”相互作用网络将环境信号，如营养状态的变化，耦合到植物细胞的膜运输和营养动态平衡的调节上。将结合遗传、生化和电生理工具，研究CBL-CIPK网络与钾和镁动态平衡的联系，重点了解质膜和液泡途径在调节营养平衡中的协调。

To grow, plants require a balanced supply of mineral nutrients, but today's soil is often deficient in essential minerals such as nitrogen, phosphorus, and potassium. To overcome this deficiency, crop production in the U.S. relies heavily on use of fertilizers, but this practice is costly, endangers environmental health and is not sustainable, because some essential minerals (e.g., potash and phosphorus rock) are limited natural resources. An alternative and more sustainable agricultural strategy is to breed plants with new traits that allow them to grow in nutrient-imbalanced soils. To achieve this goal requires better understanding of the molecular networks that allow plants to respond and adapt to the constantly changing status of mineral nutrients in the soil. This project addresses this need by studying how plants maintain the proper balance of mineral nutrients when the soil contains too much or too little of specific minerals, thus establishing the knowledgebase for breeding crops with little need of fertilizers, thereby supporting sustainable agriculture. The project will have educational benefits by providing opportunities for undergraduate and graduate students to engage in research and by reaching out to high school students, including those from underrepresented groups, through workshops and other activities aimed at promoting interest in biology research. Plants constantly monitor nutrient status in the soil and maintain nutrient homeostasis by controlling ion transport across the plasma membrane (for uptake) and tonoplast (for storage). However, the signaling mechanism linking nutrient status in the soil and membrane transport in plants is largely unknown. The principal investigator's laboratory discovered the CBL-CIPK calcium signaling network that functions in a number of cellular pathways including nutrient sensing. In addition to the CBL-CIPK pathway that targets a voltage-gated potassium channel in response to low-potassium status, their recent studies further identified a complex CBL-CIPK network that regulates vacuolar transport of a number of mineral nutrients. The findings have thus connected the CBL-CIPK signaling mechanism to the regulation of transport activities at the plasma membrane and vacuolar membrane, the two most important sites for nutrient homeostasis in plant cells. The proposed research will test the major hypothesis that a large network of "CBL-CIPK-ion channel" interactions couples the environmental signals, e.g., changes in nutrient status, to the regulation of membrane transport and nutrient homeostasis in plant cells. A combination of approaches, including genetic, biochemical, and electrophysiological tools, will be used to address connections of the CBL-CIPK network to potassium and magnesium homeostasis with a focus on understanding the coordination between the plasma membrane and vacuolar pathways in the regulation of nutrient balance.