Involved in innate immunity. Required for the expression of defense-related genes PR1A, LOX2 and CHS1 upon biotic stresses. Required for basal resistance to the fungal blast (M.grisea), bacterial blight (O.oryzae pv. oryzae, Xoo) and the herbivorous insect brown planthopper (N.lugens, BPH). May be involved in several defense signaling pathways. Involved in the promotion of seed germination. Required for the expression of alpha-amylase genes during seed germination (PubMed:15685292). Involved in resistance against the brown planthopper (BPH). Member of the BPH3 (BPH resistance locus 3) cluster which contains LECRK1, LECRK2 and LECRK3 (PubMed:25485617). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts (via kinase domain) with ADF4. Expressed in plumules, radicles and panicles. Induced by infection with the fungal blast (M.grisea) and bacterial blight (X.oryzae pv. oryzae, Xoo). Seeds silencing LECRK1 show decreased germination rates due to decreased alpha-amylase activity during seed germination. Plants silencing LECRK1 have increased susceptibility to infection by the fungal blast (M.grisea), bacterial blight (X.oryzae pv. oryzae, Xoo) and the herbivorous insect brown planthopper (N.lugens, BPH). Plants silencing LECRK1 display reduced induction of the defense-related genes PR1A, LOX2 and CHS1 after exposure to biotic stresses. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Sequencing errors.