The potassium channel GhAKT2bD is regulated by CBL–CIPK calcium signalling complexes and facilitates K⁺ allocation in cotton

Abstract

Efficient allocation of the essential nutrient potassium (K+) is a central determinant of plant ion homeostasis and involves AKT2 K+ channels. Here, we characterize four AKT2 K+ channels from cotton and report that xylem and phloem expressed GhAKT2bD facilitates K+ allocation and that AKT2‐silencing impairs plant growth and development. We uncover kinase activity‐dependent activation of GhAKT2bD‐mediated K+ uptake by AtCBL4–GhCIPK1 calcium signalling complexes in HEK293T cells. Moreover, AtCBL4–AtCIPK6 complexes known to convey activation of AtAKT2 in Arabidopsis also activate cotton GhAKT2bD in HEK293T cells. Collectively, these findings reveal an essential role for AKT2 in the source‐sink allocation of K+ in cotton and identify GhAKT2bD as subject to complex regulation by CBL–CIPK Ca2+ sensor–kinase complexes.

Molecular Mechanisms of CBL-CIPK Signaling Pathway in Plant Abiotic Stress Tolerance and Hormone Crosstalk

“…They explore the role of nutrient-induced Ca 2+ elevations as initial reactions to environmental fluctuations, which are key in modulating the activity of vital transporters and channels involved in the uptake, distribution, and storage of nutrients. Additionally, Zhang et al [34] offer insightful explanations of the relevance of CBL-CIPK and Ca 2+ signaling in potassium (K + ) allocation in cotton. The GhAKT2bD, AKT2 K + channel, which facilitates K + distribution in the xylem and phloem, is acknowledged by them as being essential.…”

“…To cope with these changes, plants have evolved sophisticated signaling networks that allow them to sense and respond to nutrient availability. One critical signaling pathway pivotal in plant responses to low nutrient conditions involves the CBL-CIPK network, which modulates the activity of various ion channels and transporters [7,34].…”

Functional Differentiation of the Duplicated Gene BrrCIPK9 in Turnip (Brassica rapa var. rapa)

“…The CBL-CIPK module is capable of responding to different stresses (e.g., drought, cold, heat, salinity, and pathogens). Specifically, it participates in the response to low-temperature and salt stress in citrus [9], in the regulation of potassium ion (K + ) transport in cotton (Gossypium hirsutum) [26], and in the response to drought, salt, and abscisic acid (ABA) stresses in Medicago [10]. The CBL-CIPK module positively regulates osmotic, salt, drought, and cold tolerance, and causes a decrease in the level of gene expression as well as a decrease in the amount of gene product (RNA or protein) in heat and fungal stress in Arabidopsis; meanwhile, AcCIPK expression affects the expression of ABA-related genes and reactive oxygen species homeostasis.…”