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

为了生长，植物需要平衡的矿质养分供应，但今天的土壤往往缺乏必需的矿物质，如氮、磷和钾。为了克服这一缺陷，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，危害环境健康，而且不可持续，因为一些必需矿物质（如钾和磷岩）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，使它们能够在营养不平衡的土壤中生长。为了实现这一目标，需要更好地理解分子网络，使植物能够响应和适应土壤中矿物质营养物质不断变化的状态。该项目通过研究植物如何在土壤中特定矿物质过多或过少的情况下保持矿物质营养的适当平衡来解决这一需求，从而为培育不需要化肥的作物建立知识库，从而支持可持续农业。该项目将通过为本科生和研究生提供参与研究的机会，并通过研讨会和其他旨在提高对生物学研究兴趣的活动，接触到高中生，包括那些代表性不足的群体，从而产生教育效益。植物不断监测土壤中的养分状况，并通过控制离子在质膜（用于吸收）和质体（用于储存）之间的转运来维持养分平衡。然而，连接土壤营养状况和植物膜转运的信号机制在很大程度上是未知的。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起作用。除了针对低钾状态的电压门控钾通道的CBL-CIPK通路外，他们最近的研究进一步确定了一个复杂的CBL-CIPK网络，该网络调节许多矿物质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稳态位点——质膜和液泡膜的运输活动调节联系起来。该研究将验证一个主要假设，即一个巨大的“cbl - cipk离子通道”相互作用网络将环境信号（如营养状况的变化）耦合到植物细胞中膜运输和营养稳态的调节中。将使用包括遗传、生化和电生理工具在内的多种方法来解决CBL-CIPK网络与钾和镁稳态的联系，重点是了解质膜和液泡途径在营养平衡调节中的协调作用。

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.