Pathogen perception by NLRs in plants and animals: Parallel worlds

Intracellular NLR (Nucleotide‐binding domain and Leucine‐rich Repeat‐containing) receptors are sensitive monitors that detect pathogen invasion of both plant and animal cells. NLRs confer recognition of diverse molecules associated with pathogen invasion. NLRs must exhibit strict intramolecular controls to avoid harmful ectopic activation in the absence of pathogens. Recent discoveries have elucidated the assembly and structure of oligomeric NLR signalling complexes in animals, and provided insights into how these complexes act as scaffolds for signal transduction. In plants, recent advances have provided novel insights into signalling‐competent NLRs, and into the myriad strategies that diverse plant NLRs use to recognise pathogens. Here, we review recent insights into the NLR biology of both animals and plants. By assessing commonalities and differences between kingdoms, we are able to develop a more complete understanding of NLR function. NLRs mediate immunity by detecting pathogen invasion: plant NLRs recognise pathogen‐secreted effectors leading to effector‐triggered immunity; animal NLRs recognise pathogen‐associated molecular patterns (PAMPs), damage‐associated molecular patterns (DAMPs) and effectors, and activate inflammatory responses. This general diagram omits specific detail in order to emphasise the parallels between animal and plant NLRs.