State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China.
Mol Plant. 2020 May 4;13(5):793-801. doi: 10.1016/j.molp.2020.03.004. Epub 2020 Mar 16.
Plants utilize nucleotide-binding, leucine-rich repeat receptors (NLRs) to detect pathogen effectors, leading to effector-triggered immunity. The NLR ZAR1 indirectly recognizes the Xanthomonas campestris pv. campestris effector AvrAC and Pseudomonas syringae effector HopZ1a by associating with closely related receptor-like cytoplasmic kinase subfamily XII-2 (RLCK XII-2) members RKS1 and ZED1, respectively. ZAR1, RKS1, and the AvrAC-modified decoy PBL2 form a pentameric resistosome in vitro, and the ability of resistosome formation is required for AvrAC-triggered cell death and disease resistance. However, it remains unknown whether the effectors induce ZAR1 oligomerization in the plant cell. In this study, we show that both AvrAC and HopZ1a can induce oligomerization of ZAR1 in Arabidopsis protoplasts. Residues mediating ZAR1-ZED1 interaction are indispensable for HopZ1a-induced ZAR1 oligomerization in vivo and disease resistance. In addition, ZAR1 residues required for the assembly of ZAR1 resistosome in vitro are also essential for HopZ1a-induced ZAR1 oligomerization in vivo and disease resistance. Our study provides evidence that pathogen effectors induce ZAR1 resistosome formation in the plant cell and that the resistosome formation triggers disease resistance.
植物利用核苷酸结合、富含亮氨酸重复受体（NLRs）来检测病原体效应子，从而引发效应子触发的免疫。NLR ZAR1 通过与密切相关的受体样细胞质激酶亚家族 XII-2（RLCK XII-2）成员 RKS1 和 ZED1 分别关联，间接识别黄单胞菌野油菜致病变种效应子 AvrAC 和丁香假单胞菌效应子 HopZ1a。ZAR1、RKS1 和被 AvrAC 修饰的诱饵 PBL2 在体外形成五聚体抗性体，并且抗性体形成的能力是触发 AvrAC 引发的细胞死亡和抗病性所必需的。然而，目前尚不清楚效应子是否会在植物细胞中诱导 ZAR1 寡聚化。在本研究中，我们表明 AvrAC 和 HopZ1a 均可诱导拟南芥原生质体中 ZAR1 的寡聚化。介导 ZAR1-ZED1 相互作用的残基对于 HopZ1a 诱导的 ZAR1 寡聚化和体内抗病性是不可或缺的。此外，在体外组装 ZAR1 抗性体所需的 ZAR1 残基对于 HopZ1a 诱导的 ZAR1 寡聚化和体内抗病性也是必需的。我们的研究提供了证据表明病原体效应子在植物细胞中诱导 ZAR1 抗性体形成，并且该抗性体形成触发了抗病性。
