Activation of TIR signalling boosts pattern-triggered immunity

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 pathogens(1). 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.

Automated summary

Plant immune responses are mainly activated by two types of receptors, with the activation of TIR signaling playing a crucial role in pattern-triggered immunity (PTI). Activation of TIR signaling can boost plant defense mechanisms and increase resistance against pathogens.