Defence against pathogens relies on intracellular nucleotide-binding, leucine-rich repeat immune receptors (NLRs) in plants. Hormone signaling including abscisic acid (ABA) pathways are activated by NLRs and play pivotal roles in defence against different pathogens. However, little is known about how hormone signaling pathways are activated by plant immune receptors. Here, we report that a plant NLR Sw-5b mimics the behavior of the ABA receptor and directly employs the ABA central regulator PP2C-SnRK2 complex to activate an ABA-dependent defence against viral pathogens. PP2C4 interacts with and constitutively inhibits SnRK2.3/2.4. Behaving in a similar manner as the ABA receptor, pathogen effector ligand recognition triggers the conformational change of Sw-5b NLR that enables binding to PP2C4 via the NB domain. This receptor-PP2C4 binding interferes with the interaction between PP2C4 and SnRK2.3/2.4, thereby releasing SnRK2.3/2.4 from PP2C4 inhibition to activate an ABA-specific antiviral immunity. These findings provide important insights into the activation of hormone signaling pathways by plant immune receptors.

植物对病原体的防御依赖于细胞内核苷酸结合、富含亮氨酸的重复免疫受体 (NLR)。包括脱落酸 (ABA) 通路在内的激素信号传导由 NLR 激活，在防御不同病原体方面发挥着关键作用。然而，人们对植物免疫受体如何激活激素信号通路知之甚少。在这里，我们报道植物 NLR Sw-5b 模仿 ABA 受体的行为，并直接利用 ABA 中央调节剂 PP2C-SnRK2 复合物来激活针对病毒病原体的 ABA 依赖性防御。 PP2C4 与 SnRK2.3/2.4 相互作用并组成型抑制。与 ABA 受体的行为方式相似，病原体效应配体识别会触发 Sw-5b NLR 的构象变化，从而能够通过 NB 结构域与 PP2C4 结合。这种受体-PP2C4 结合干扰 PP2C4 和 SnRK2.3/2.4 之间的相互作用，从而将 SnRK2.3/2.4 从 PP2C4 抑制中释放出来，从而激活 ABA 特异性抗病毒免疫。这些发现为植物免疫受体激活激素信号通路提供了重要的见解。