Abstract
The highly selective segregation of molecules at the plasma membrane (PM) to form domains is a widespread phenomenon. But how distinct signaling platforms are established and maintained by specific signals remains unclear. Here, we show that the receptor of Rapid Alkalinization Factor 1 (RALF1), the FERONIA (FER) receptor kinase, physically interacts with C2 domain ABA–related (CAR) proteins to control the nano-organization of the PM and to regulate extracellular signal transduction in Arabidopsis. During this process, the RALF1–FER pathway upregulates CAR protein synthesis, which then controls the membrane lipid order. This might act as a rapid feedforward loop to stabilize FER in PM nanodomains. FER then interacts with and phosphorylates CARs, reducing their lipid-binding ability, which might break the feedback regulation and downregulate CAR activity at latter time point. Similar to fer mutant, a pentuple car14569 mutant inhibits flg22-induced FLS2-BAK1 complex formation, which ultimately impacts plant immunity. Together, we proposed that the FER-CAR module controls the dynamics of the PM nano-organization during RALF signaling through a self-contained amplifying loop including both positive and negative feedbacks.
Competing Interest Statement
The authors have declared no competing interest.