Plant Calcium Signaling in Response to Potassium Deficiency.

Xiaoping Wang,Biping Zhu,Zhonghao Jiang,Ling Hao

doi:10.3390/ijms19113456

Xiaoping Wang, Biping Zhu + Show 2 more

Open Access

https://doi.org/10.3390/ijms19113456

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Abstract

Potassium (K+) is an essential macronutrient of living cells and is the most abundant cation in the cytosol. K+ plays a role in several physiological processes that support plant growth and development. However, soil K+ availability is very low and variable, which leads to severe reductions in plant growth and yield. Various K+ shortage-activated signaling cascades exist. Among these, calcium signaling is the most important signaling system within plant cells. This review is focused on the possible roles of calcium signaling in plant responses to low-K+ stress. In plants, intracellular calcium levels are first altered in response to K+ deficiency, resulting in calcium signatures that exhibit temporal and spatial features. In addition, calcium channels located within the root epidermis and root hair zone can then be activated by hyperpolarization of plasma membrane (PM) in response to low-K+ stress. Afterward, calcium sensors, including calmodulin (CaM), CaM-like protein (CML), calcium-dependent protein kinase (CDPK), and calcineurin B-like protein (CBL), can act in the sensing of K+ deprivation. In particular, the important components regarding CBL/CBL-interacting protein kinase (CBL/CIPK) complexes-involved in plant responses to K+ deficiency are also discussed.

Highlights

Potassium (K+) is an essential macronutrient and is essential for plant growth and development [1]
K+ deprivation leads to a strong increase in chlorophyll degradation; K+ deficiency-related symptoms include brown scorching and curling of leaf tips, as well as interveinal chlorosis [8]
A Raf-like MAPKK kinase (AtILK1) directly interacts with AtHAK5 in conjunction with the AtCML9, promoting AtHAK5 accumulation on the membrane [100]. These results indicate that calcium sensor proteins may play vital roles in connecting calcium signaling and downstream target proteins during plant responses to K+ deficiency

Summary

Introduction

Potassium (K+) is an essential macronutrient and is essential for plant growth and development [1]. A Raf-like MAPKK kinase (AtILK1) directly interacts with AtHAK5 in conjunction with the AtCML9, promoting AtHAK5 accumulation on the membrane [100] These results indicate that calcium sensor proteins may play vital roles in connecting calcium signaling and downstream target proteins during plant responses to K+ deficiency. Another important member of the calcium sensor relays is CBL, which, like CaM and CML, has been shown to lack responder domains [101]. CBLs and CBL-interacting protein kinases (CIPKs) often form the CBL/CIPK complexes, perceiving calcium signals and relaying the signals to downstream responses in plants under low-K+ stress [31,32,33,34,35,37,102,103,104,105]

CBL Proteins

Conclusions and Perspectives