CPK1 Activates CNGCs Through Phosphorylation for Calcium 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.