CPK1 activates CNGCs through phosphorylation for Ca2+ signaling to promote root hair growth in Arabidopsis

The study explores the role of CPK1 in promoting root hair growth in Arabidopsis by activating cyclic nucleotide-gated channels (CNGCs) through phosphorylation, which is essential for calcium signaling. It identifies Ser26 as the primary phosphorylation site on CNGC9, crucial for channel activation. Loss-of-function mutants (cpk1-1 and cpk1-2) showed defects in root hair growth, similar to mutants lacking functional CNGC5/6/9. Phospho-mimic CNGCs rescued these defects, underscoring the importance of the CPK1-CNGC signaling module. The research highlights CPK1 as a key regulator of cytosolic Ca2+ gradients necessary for root hair elongation, suggesting a feedback loop between CPK1 and CNGCs to sustain these gradients.