Original data for Co-Immunoprecipitations from "The Arabidopsis TIR-NBS-LRR CSA1 guards BAK1 BIR3 homeostasis and mediates pattern- and effector-induced plant immune responses"

Arabidopsis BAK1/SERK3, a co-receptor of leucine-rich repeat pattern recognition receptors (PRR), mediates pattern-triggered immunity (PTI). Genetic inactivation of BAK1 or BAK1-interacting receptors (BIR) causes cell death. We found that the TIR-NBS-LRR protein CONSTITUTIVE SHADE-AVOIDANCE 1 (CSA1) physically interacts with BIR3, but not with BAK1. Cell death in bak1-4 and bak1-4 bir3-2 mutants is dependent on CSA1 and on components of effector-triggered immunity-(ETI) pathways, including EDS1, PAD4, and the plant hormone, salicylic acid. Effector HopB1-mediated perturbation of BAK1 also results in CSA1-dependent cell death. Likewise, microbial pattern pg23-induced cell death, but not PTI responses, require CSA1. Thus, CSA1 integrates pattern- and effector-mediated cell death pathways downstream of BAK1. CSA1 guards BIR3 BAK1 homeostasis, and de-repression of CSA1 in the absence of intact BAK1 and BIR3 triggers ETI cell death. This suggests that PTI and ETI pathways are activated downstream of BAK1 for efficient plant immunity.