Plants deploy intracellular receptors to counteract pathogen effectors that suppress cell-surface receptor-mediated immunity. To what extent pathogens manipulate also immunity mediated by intracellular receptors, and how plants tackle such manipulation, remains unknown. Arabidopsis thaliana encodes three similar ADR1 class helper NLRs (ADR1, ADR1-L1 and ADR1-L2), crucial in plant immunity initiated by intracellular receptors. Here, we report that Pseudomonas syringae AvrPtoB, an E3 ligase effector, suppresses ADR1-L1- and ADR1-L2-mediated cell death. ADR1, however, evades such suppression by diversifying two ubiquitination sites targeted by AvrPtoB. The intracellular sensor SNC1 interacts with and guards the CCR domains of ADR1-L1/L2. Removal of ADR1-L1/L2 or delivery of AvrPtoB activates SNC1, which then signals through ADR1 to trigger immunity. Our work elucidates the long sought-after function of SNC1 in defense, and also how plants can use dual strategies, sequence diversification and a multiple layered guard-guardee system, to counteract pathogen attack on core immunity functions.
Wang, Ming-Yu and Chen, Jun-Bin and Wu, Rui and Guo, Hai-Long and Chen, Yan and Li, Zhen-Ju and Wei, Lu-Yang and Liu, Chuang and He, Sheng-Feng and Du, Mei-Da and Guo, Ya-long and Peng, You-Liang and Jones, Jonathan and Weigel, Detlef and Huang, Jian-Hua and Zhu, Wangsheng and Administrator, Sneak Peek, The Immune Receptor SNC1 Monitors Helper NLRs Targeted by a Bacterial Effector. Available at SSRN: https://ssrn.com/abstract=4439681 or http://dx.doi.org/10.2139/ssrn.4439681
This version of the paper has not been formally peer reviewed.
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