Journal Article

Loss of the common immune coreceptor BAK1 leads to NLR-dependent cell death

Wu, Yujun, Zhan, Yanyan, Li, Jia, Yan, Li, Zhou, Jian-Min, Liu, Hongyan, He, Kai, Gao, Yang, Kemmerling, Birgit, Kui, Hong

2020

Overview

Plants utilize a two-tiered immune system consisting of pattern recognition receptor (PRR)-triggered immunity (PTI) and effector-triggered immunity (ETI) to defend themselves against pathogenic microbes. The receptor protein kinase BAK1 plays a central role in multiple PTI signaling pathways in Arabidopsis. However, double mutants made by BAK1 and its closest paralog BKK1 exhibit autoimmune phenotypes, including cell death resembling a typical nucleotide-binding leucine-rich repeat protein (NLR)-mediated ETI response. The molecular mechanisms of the cell death caused by the depletion of BAK1 and BKK1 are poorly understood. Here, we show that the cell-death phenotype of bak1 bkk1 is suppressed when a group of NLRs, ADR1s, are mutated, indicating the cell-death of bak1 bkk1 is the consequence of NLR activation. Furthermore, introduction of a Pseudomonas syringae effector HopB1, which proteolytically cleaves activated BAK1 and its paralogs via either gene transformation or bacterium-delivery, results in a cell-death phenotype in an ADR1s-dependent manner. Our study thus pinpoints that BAK1 and its paralogs are likely guarded by NLRs.

• Publisher: National Academy of Sciences
• Subject: Apoptosis / Arabidopsis / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / Biological Sciences / Cell Death / Depletion / Genetic transformation / Immune system / Immunity / Kinases / Leucine / Molecular modelling / Mortality / NLR Proteins / Nucleotides / Pattern recognition / Pattern recognition receptors / Phenotypes / Plant Biology / Plant Immunity / Protein kinase / Protein Kinases - genetics / Protein Kinases - metabolism / Protein-Serine-Threonine Kinases - genetics / Protein-Serine-Threonine Kinases - metabolism / Proteins / Receptors