A chemical genetic approach demonstrates that MPK 3/ MPK 6 activation and NADPH oxidase‐mediated oxidative burst are two independent signaling events in plant immunity

作者：Juan Xu, Jie Xie, Chengfei Yan, Xiaoqin Zou, Dongtao Ren, Shuqun Zhang · 发表于：The Plant Journal · 年份：2013 · DOI：10.1111/tpj.12382 · 被引用次数：202 · 研究领域：Plant-Microbe Interactions and Immunity、Plant Pathogenic Bacteria Studies、Plant Stress Responses and Tolerance

Plant recognition of pathogen-associated molecular patterns (PAMPs) such as bacterial flagellin-derived flg22 triggers rapid activation of mitogen-activated protein kinases (MAPKs) and generation of reactive oxygen species (ROS). Arabidopsis has at least four PAMP/pathogen-responsive MAPKs: MPK3, MPK6, MPK4 and MPK11. It was speculated that these MAPKs may function downstream of ROS in plant immunity because of their activation by exogenously added H2 O2 . MPK3/MPK6 or their orthologs in other plant species have also been reported to be involved in the ROS burst from the plant respiratory burst oxidase homolog (Rboh) of the human neutrophil gp91phox. However, detailed genetic analysis is lacking. Using a chemical genetic approach, we generated a conditional loss-of-function mpk3 mpk6 double mutant. Consistent with results obtained using a conditionally rescued mpk3 mpk6 double mutant generated previously, the results obtained using the new conditional loss-of-function mpk3 mpk6 double mutant demonstrate that the flg22-triggered ROS burst is independent of MPK3/MPK6. In Arabidopsis mutants lacking a functional AtRbohD, the flg22-induced ROS burst was completely blocked. However, activation of MPK3/MPK6 was not affected. Based on these results, we conclude that the rapid ROS burst and MPK3/MPK6 activation are two independent early signaling events in plant immunity, downstream of FLS2. We also found that MPK4 negatively affects the flg22-induced ROS burst. In addition, salicyli...