Acts on phosphatidylinositol (PtdIns) in the first committed step in the production of the second messenger inositol-1,4,5-trisphosphate (By similarity). Necessary for proper organization of the trans-Golgi network (TGN) and post-Golgi secretion in root hairs. Together with PI4KB1, required during polarized root hair expansion and pollen tube elongation. Functions redundantly with PI4KB1 upstream of the cold response phosphoinositide-dependent phospholipase C (PI-PLC) pathway. a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol) + ATP = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol 4-phosphate) + ADP + H(+) Associated to tip-localized membranes in growing root hairs. The PPC (Plant PI4K Charged) region is involved in membrane targeting and phospholipid binding. When associated with PI4KB1 disruption: aberrant root hair morphologies, and short and wavy pollen tubes. Belongs to the PI3/PI4-kinase family. Type III PI4K subfamily.