Involved in negative regulation of abscisic acid response in seed germination. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Slight enhancement in abscisic acid-inhibited germination. Redundant with LECRKA4.1 and LECRKA4.3. In the C-terminal section; belongs to the protein kinase superfamily. Ser/Thr protein kinase family. In the N-terminal section; belongs to the leguminous lectin family.