Kinase that can phosphorylate various inositol polyphosphate such as Ins(3,4,5,6)P4 or Ins(1,3,4)P3 and participates in phytic acid biosynthesis in developing seeds. Phytic acid is the primary storage form of phosphorus in cereal grains and other plant seeds (By similarity). May be involved in the negative regulation of osmotic stress signaling (PubMed:18421420, PubMed:22038091). 1D-myo-inositol 3,4,5,6-tetrakisphosphate + ATP = 1D-myo-inositol 1,3,4,5,6-pentakisphosphate + ADP + H(+) 1D-myo-inositol 1,3,4-trisphosphate + ATP = 1D-myo-inositol 1,3,4,5-tetrakisphosphate + ADP + H(+) 1D-myo-inositol 1,3,4-trisphosphate + ATP = 1D-myo-inositol 1,3,4,6-tetrakisphosphate + ADP + H(+) Binds 2 magnesium ions per subunit. Monomer. Expressed in roots, leaves, flowers, anthers and embryos. By drought and salt stresses. No visible phenotype under normal growth conditions, but mutant plants show increased sensitivity to salt and drought stresses. Belongs to the ITPK1 family.