Membrane-localized leucine-rich repeat receptor kinases(LRR-RKs)sense diverse extracellular signals,and coordinate and specify cellular functions in plants.However,functional understanding and identifica-tion of the cellular signaling of most LRR-RKs remain a major challenge owing to their genetic redundancy,the lack of ligand information,and subtle phenotypes of LRR-RK overexpression.Here,we report an engi-neered rapamycin-inducible dimerization(RiD)receptor system that triggers a receptor-specific LRR-RK signaling independent of their cognate ligands or endogenous receptors.Using the RiD-receptors,we demonstrated that the rapamycin-mediated association of chimeric cytosolic kinase domains from the BRI1/BAK1 receptor/co-receptor,but not the BRI1/BRI1 orBAK1/BAK1 homodimer,is sufficient to activate downstream brassinosteroid signaling and physiological responses.Furthermore,we showed that the en-gineered RiD-FLS2/BAK1 could activate flagellin-22-mediated immune signaling and responses.Using the RiD system,we also identified the potential function of an unknown orphan receptor in immune signaling and revealed the differential activities of SERK co-receptors of LRR-RKs.Our results indicate that the RiD method can serve as a synthetic biology tool for precise temporal manipulation of LRR-RK signaling and for understanding LRR-RK biology.