The CBP60b-14-3-3 functional module regulates immunity in arabidopsis

Transcriptional reprogramming is a critical process in plant immune responses, in which Calmodulin-Binding Protein 60b (CBP60b), a plant-specific atypical transcription factor family, plays an essential role. However, how its transcriptional activity is regulated during immunity remains unclear. Here, we report that 14-3-3 proteins, conserved scaffolding proteins in eukaryotes, interact with CBP60b in a calcium-dependent manner and enhance its transcriptional activity on downstream genes. The 14-3-3 variant deficient in calcium binding, 14-3-3λ^G216A, disrupted the interaction with CBP60b and failed to fully complement the pathogen-sensitive phenotype of the 14-3-3λ;κ mutant. Furthermore, we show that the pathogen-induced transcriptional upregulation of 14-3-3λ and 14-3-3κ is dependent on CBP60b. Finally, genetic evidence demonstrates that 14-3-3s are required for CBP60b function. Collectively, our findings reveal that CBP60b and 14-3-3 proteins form an interactome-mediated positive feedback loop to orchestrate immune responses in a calcium-dependent manner.