The ZAR1 Resistosome is a Calcium-Permeable Channel Triggering Plant Immune Signaling
Guozhi Bi, Min Su, Nan Li, Yu Liang, Song Dang, Jiachao Xu, Meijuan Hu, Jizong Wang, Minxia Zou, Yanan Deng, Qiyu Li, Shijia Huang, Jiejie Li, Jijie Chai, Kangmin He, Yuhang Chen, and Jian-Min Zhou
Nucleotide-binding, leucine-rich repeat receptors (NLRs) are major immune receptors in plants and animals. Upon activation, the Arabidopsis NLR protein ZAR1 forms a pentameric resistosome in vitro and triggers immune responses and cell death in plants. In this study we employed single-molecule imaging to show that the activated ZAR1 protein can form pentameric complexes in the plasma membrane (PM). The ZAR1 resistosome displayed ion channel activity in Xenopus oocytes in a manner dependent on a conserved acidic residue Glu11 situated in the channel pore. Pre-assembled ZAR1 resistosome was readily incorporated into planar lipid-bilayers and displayed calcium-permeable cation-selective channel activity. Furthermore, we show that activation of ZAR1 in the plant cell led to Glu11-dependent Ca2+ influx, perturbation of subcellular structures, production of reactive oxygen species and cell death. The results thus support that the ZAR1 resistosome acts as a calcium-permeable cation channel to trigger immunity and cell death.