WRKY Transcription Factors Phosphorylated by MAPK Regulate a Plant Immune NADPH Oxidase in Nicotiana benthamiana  . Issue 9 (15th September 2015)

• Record Type: Journal Article
• Authors: Adachi, Hiroaki; Nakano, Takaaki; Miyagawa, Noriko; Ishihama, Nobuaki; Yoshioka, Miki; Katou, Yuri; Yaeno, Takashi; Shirasu, Ken; Yoshioka, Hirofumi
• Is Part Of: The Plant Cell. Volume 27:Issue 9(2015)
• Page Start: 2645
• Page End: 2663
• Publication Date: 2015-09-15
• DOI: 10.1105/tpc.15.00213
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract : Phosphorylation of WRKYs by MAPK regulates an NADPH oxidase, demonstrating that the MAPK-WRKY pathway is required for the ROS burst in effector-triggered immunity via upregulation of RBOHB. Abstract: Pathogen attack sequentially confers pattern-triggered immunity (PTI ) and effector-triggered immunity (ETI ) after sensing of pathogen patterns and effectors by plant immune receptors, respectively. Reactive oxygen species (ROS ) play pivotal roles in PTI and ETI as signaling molecules. Nicotiana benthamiana RBOHB, an NADPH oxidase, is responsible for both the transient PTI ROS burst and the robust ETI ROS burst. Here, we show that RBOHB transactivation mediated by MAPK contributes to R3a/AVR3a-triggered ETI (AVR3a-ETI) ROS burst. RBOHB is markedly induced during the ETI and INF1-triggered PTI (INF1-PTI), but not flg22-tiggered PTI (flg22-PTI). We found that the RBOHB promoter contains a functional W-box in the R3a/AVR3a and INF1 signal-responsive cis -element. Ectopic expression of four phospho-mimicking mutants of WRKY transcription factors, which are MAPK substrates, induced RBOHB, and yeast one-hybrid analysis indicated that these mutants bind to the cis -element. Chromatin immunoprecipitation assays indicated direct binding of the WRKY to the cis -element in plants. Silencing of multiple WRKY genes compromised the upregulation of RBOHB, resulting in impairment of AVR3a-ETI and INF1-PTI ROS bursts, but not the flg22-PTI ROS burst. These results suggest that the MAPK -WRKY pathway is required for AVR3a-ETI and INF1-PTI ROS bursts by activation of RBOHB .