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An RLP23–SOBIR1–BAK1 complex mediates NLP-triggered immunity


Plants and animals employ innate immune systems to cope with microbial infection. Pattern-triggered immunity relies on the recognition of microbe-derived patterns by pattern recognition receptors (PRRs). Necrosis and ethylene-inducing peptide 1-like proteins (NLPs) constitute plant immunogenic patterns that are unique, as these proteins are produced by multiple prokaryotic (bacterial) and eukaryotic (fungal, oomycete) species. Here we show that the leucine-rich repeat receptor protein (LRR-RP) RLP23 binds in vivo to a conserved 20-amino-acid fragment found in most NLPs (nlp20), thereby mediating immune activation in Arabidopsis thaliana. RLP23 forms a constitutive, ligand-independent complex with the LRR receptor kinase (LRR-RK) SOBIR1 (Suppressor of Brassinosteroid insensitive 1 (BRI1)-associated kinase (BAK1)-interacting receptor kinase 1), and recruits a second LRR-RK, BAK1, into a tripartite complex upon ligand binding. Stable, ectopic expression of RLP23 in potato (Solanum tuberosum) confers nlp20 pattern recognition and enhanced immunity to destructive oomycete and fungal plant pathogens, such as Phytophthora infestans and Sclerotinia sclerotiorum. PRRs that recognize widespread microbial patterns might be particularly suited for engineering immunity in crop plants.

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Figure 1: RLP23 confers sensitivity to nlp20.
Figure 2: nlp20 interacts specifically with RLP23 in vitro a,b and in planta c,d.
Figure 3: RLP23 interacts with SOBIR1, BAK1 and other members of the SERK protein family, and these proteins are required for nlp20-mediated defence activation.
Figure 4: RLP23 physically interacts with SOBIR1 and BAK1.
Figure 5: RLP23-mediated pathogen resistance.


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Research in the laboratory of T.N. was funded by DFG grant Nu 70/9, funds of the University of Tübingen and SFB1101. Research in the G.V.d.A. laboratory was partly financed by a ‘more with less’ grant of the Netherlands Organization for Scientific Research. We are grateful to C. Oecking for critical discussions, to K. Berendzen for technical advice and to D. Chinchilla and J. Felix for providing an anti-SERK-antibody.

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T.N., G.V.d.A., J.C., R.H., I.A., H.B., M.A., J.I., S.O., T.M.R., C.G., A.A.G. and E.K. conceived and designed the experiments; I.A., H.B., M.A., C.F., J.I., N.W., C.G., T.M.R., H.Z. and E.K. conducted experiments and analysed data; C.B. produced transgenic plants; and I.A., H.B. and T.N. wrote the manuscript. All authors discussed the results and commented on the manuscript.

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Correspondence to Thorsten Nürnberger.

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Albert, I., Böhm, H., Albert, M. et al. An RLP23–SOBIR1–BAK1 complex mediates NLP-triggered immunity. Nature Plants 1, 15140 (2015).

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