Plants have developed sophisticated strategies to coordinate growth and immunity, but our understanding of the underlying mechanism remains limited. In this study, we identified a novel molecular module that regulates plant growth and defense in both compatible and incompatible infections. This module consisted of BZR1, a key transcription factor in brassinosteroid (BR) signaling, and EDS1, an essential positive regulator of plant innate immunity. We found that EDS1 interacts with BZR1 and suppresses its transcriptional activities. Consistently, upregulation of EDS1 function by a virulent Pseudomonas syringae strain or salicylic acid treatment inhibited BZR1-regulated expression of BR-responsive genes and BR-promoted growth. Furthermore, we showed that the cytoplasmic fraction of BZR1 positively regulates effector-triggered immunity (ETI) controlled by the TIR-NB-LRR protein RPS4, which is attenuated by BZR1’s nuclear translocation. Mechanistically, cytoplasmic BZR1 facilitated AvrRps4-triggered dissociation of EDS1 and RPS4 by binding to EDS1, thus leading to efficient activation of RPS4-controlled ETI. Notably, transgenic expression of a mutant BZR1 that accumulates exclusively in the cytoplasm improved pathogen resistance without compromising plant growth. Collectively, these results shed new light on plant growth-defense coordination and reveal a previously unknown function for the cytoplasmic fraction of BZR1. The BZR1-EDS1 module may be harnessed for the simultaneous improvement of crop productivity and pathogen resistance.

植物已经开发出复杂的策略来协调生长和免疫，但我们对潜在机制的理解仍然有限。在这项研究中，我们发现了一种新的分子模块，可以在相容和不相容的感染中调节植物的生长和防御。该模块由油菜素内酯 (BR) 信号传导中的关键转录因子 BZR1 和植物先天免疫的重要正调节因子 EDS1 组成。我们发现 EDS1 与 BZR1 相互作用并抑制其转录活性。一致地，毒力丁香假单胞菌上调 EDS1 功能菌株或水杨酸处理抑制 BZR1 调节的 BR 反应基因的表达和 BR 促进的生长。此外，我们发现 BZR1 的细胞质部分正向调节由 TIR-NB-LRR 蛋白 RPS4 控制的效应触发免疫 (ETI)，而 RPS4 会因 BZR1 的核转位而减弱。从机制上讲，细胞质 BZR1 通过与 EDS1 结合促进 AvrRps4 触发的 EDS1 和 RPS4 解离，从而导致 RPS4 控制的 ETI 的有效激活。值得注意的是，仅在细胞质中积累的突变 BZR1 的转基因表达提高了病原体的抗性，而不会影响植物的生长。总的来说，这些结果为植物生长防御协调提供了新的思路，并揭示了 BZR1 细胞质部分以前未知的功能。