Plays a role in pattern-triggered immunity (PTI) signaling induced by pathogen-associated molecular patterns (PAMPs). Acts as a receptor for PIP1 defense peptide. PIP1 is an endogenous secreted peptide that acts as elicitor of immune response and positive regulator of defense response (PubMed:25188390). Involved in the control of seed germination speed, in tolerance to oxidative stress and in maintaining seed longevity (PubMed:20811905). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with PIP1. Expressed in roots, stems and dry seeds. Expressed at junctions between organs, such as the insertion zones of stamens, petals and sepals, the transition zones of floral stem and pedicel, pedicel and silique, and floral stem and cauline leaves. In the embryo, expressed from the heart stage to dry seeds. In germinating seeds, expression decreases during imbibition and increasees again 72 hours after imbibition, during the establishment of the seedling. Slightly delayed seed germination. May be due to a competing acceptor splice site. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.