Involved in negative regulation of abscisic acid response in seed germination. Involved in resistance response to the pathogenic bacteria Pseudomonas syringae. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Strongly expressed in the vascular system and trichomes of the leaves. Also expressed in guard cells, anthers, stigmas and germinating seeds, but not found in petals or roots. Increased susceptibility to the bacteria Pseudomonas syringae, characterized by stronger necrotic symptoms and higher bacterial proliferation (PubMed:25083911). Slight enhancement in abscisic acid-inhibited germination. Redundant with LECRKA4.2 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.