Plant physiology and development essentially depend on sufficient uptake of various essential nutritive ions via their roots and their appropriate transport and distribution within the organism. Many of these essential nutrients are heterogeneously distributed in the soil or are available in fluctuating concentrations. This natural situation requires constant regulatory adjustment and balancing of nutrient uptake and homeostasis. Here, we review recent findings on the role of Ca2+ signals and Ca2+-dependent regulation via the CBL-CIPK Ca2+ sensor-protein kinase network in these processes. We put special emphasis on Ca2+ controlled processes that contribute to establishing the homeostasis of macro-nutrients like potassium (K+), nitrogen (N), and magnesium (Mg2+) and on the micro-nutrient iron (Fe). Increasing experimental evidence indicates the occurrence of nutrient-specific, spatially and temporally defined cytoplasmic Ca2+ elevations as early responses to nutrient fluctuations. Specific CBL-CIPK complexes translate these signals into phosphorylation regulation of important channels and transporters like AKT1, NPF6.3/NRT1.1, AMT1, SLAC1, TPK1 and IRT1. We discuss a crucial and coordinating role for these Ca2+ signaling mechanisms in regulating the sensing, uptake, distribution and storage of various ions. Finally, we reflect on the emerging multifaceted and potentially integrating role of the "nutrient" kinase CIPK23 in regulating multiple nutrient responses. From this inventory, we finally deduce potential mechanisms that can convey the coordinated regulation of distinct steps in the transport of one individual ion and mechanisms that can bring about the integration of adaptive responses to fluctuations of different ions to establish a faithfully balanced plant nutrient homeostasis.

中文翻译：

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CBL-CIPK 钙信号网络作为植物营养关键调控中心的新兴作用

植物生理学和发育基本上取决于通过根部对各种必需营养离子的充分吸收以及它们在生物体内的适当运输和分布。许多这些必需营养素在土壤中分布不均或以波动的浓度提供。这种自然情况需要不断的调节和平衡养分吸收和体内平衡。在这里，我们回顾了在这些过程中通过 CBL-CIPK Ca2+ 传感器-蛋白激酶网络对 Ca2+ 信号和 Ca2+ 依赖性调节的作用的最新发现。我们特别强调有助于建立钾 (K+)、氮 (N) 和镁 (Mg2+) 等常量营养素和微量营养素铁 (Fe) 稳态的 Ca2+ 控制过程。越来越多的实验证据表明，作为对营养波动的早期反应，特定营养的、空间和时间上定义的细胞质 Ca2+ 升高的发生。特定的 CBL-CIPK 复合物将这些信号转化为重要通道和转运蛋白（如 AKT1、NPF6.3/NRT1.1、AMT1、SLAC1、TPK1 和 IRT1）的磷酸化调节。我们讨论了这些 Ca2+ 信号机制在调节各种离子的传感、吸收、分布和存储方面的关键和协调作用。最后，我们反思了“营养”激酶 CIPK23 在调节多种营养反应中的新兴多方面和潜在整合作用。从这份清单中，