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

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 Ca 2+ sensor-kinase complexes.