Sara Kim1,†, Jeonghyang Park1,†, Byeong Wook Jeon2,3,†, Geonhee Hwang1, Na Young Kang2, Yeim We1, Won-Young Park1, Eunkyoo Oh1,*, Jungmook Kim2,3,4,*
1Department of Life Sciences, Korea University, Seoul, Korea
2Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, Korea
3Kumho Life Science Laboratory, Chonnam National University, Gwangju, Korea
4Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, Korea
†These authors contributed equally to this work.
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 identification of the cellular signaling of most LRR-RKs remain a major challenge owing to their genetic redundancy, lack of ligand information, and subtle phenotypes of LRR-RK overexpression. Here, we report an engineered 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 or BAK1/BAK1 homodimer, is sufficient to activate downstream brassinosteroid signaling and physiological responses and that the engineered RiD-FLS2/BAK1 activates flagellin-22-mediated immune signaling and responses. 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 demonstrated 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.