Plant immune responses are mainly activated by two types of receptor. Pattern recognition receptors localized on the plasma membrane perceive extracellular microbial features, and nucleotide-binding leucine-rich repeat receptors (NLRs) recognize intracellular effector proteins from pathogens¹. NLRs possessing amino-terminal Toll/interleukin-1 receptor (TIR) domains activate defence responses via the NADase activity of the TIR domain^2,3. Here we report that activation of TIR signalling has a key role in pattern-triggered immunity (PTI) mediated by pattern recognition receptors. TIR signalling mutants exhibit attenuated PTI responses and decreased resistance against pathogens. Consistently, PTI is compromised in plants with reduced NLR levels. Treatment with the PTI elicitor flg22 or nlp20 rapidly induces many genes encoding TIR-domain-containing proteins, which is likely to be responsible for activating TIR signalling during PTI. Overall, our study reveals that activation of TIR signalling is an important mechanism for boosting plant defence during PTI.

植物免疫反应主要由两种受体激活。位于质膜上的模式识别受体感知细胞外的微生物特征，而核苷酸结合的富含亮氨酸的重复受体（NLR）则识别来自病原体的细胞内效应蛋白¹ 。拥有氨基末端 Toll/白细胞介素 1 受体 (TIR) 结构域的 NLR 通过 TIR 结构域的 NADase 活性激活防御反应^2,3 。在这里，我们报道 TIR 信号的激活在模式识别受体介导的模式触发免疫（PTI）中发挥关键作用。 TIR 信号突变体表现出 PTI 反应减弱和对病原体的抵抗力降低。一致地，NLR 水平降低的植物中的 PTI 会受到损害。用 PTI 引发子 flg22 或 nlp20 处理可快速诱导许多编码含有 TIR 结构域的蛋白质的基因，这可能是 PTI 期间激活 TIR 信号传导的原因。总的来说，我们的研究表明 TIR 信号的激活是 PTI 期间增强植物防御的重要机制。