A Ralstonia solanacearum effector targets TGA transcription factors to subvert salicylic acid signaling.

Abstract

The bacterial pathogen Ralstonia solanacearum causes wilt disease on Arabidopsis thaliana and tomato (Solanum lycopersicum). This pathogen uses type III effectors to inhibit the plant immune system; however, how individual effectors interfere with plant immune responses, including transcriptional reprograming, remain elusive. Here, we show that the type III effector RipAB targets Arabidopsis TGACG SEQUENCE-SPECIFIC BINDING PROTEIN (TGA) transcription factors, the central regulators of plant immune gene regulation, via physical interaction in the nucleus to dampen immune responses. RipAB was required for R. solanacearum virulence on wild-type tomato and Arabidopsis but not Arabidopsis tga1 tga4 and tga2 tga5 tga6 mutants. Stable expression of RipAB in Arabidopsis suppressed the pathogen-associated molecular pattern-triggered reactive oxygen species (ROS) burst and immune gene induction as well as salicylic acid (SA) regulons including RBOHD and RBOHF, responsible for ROS production, all of which were phenocopied by the tga1 tga4 and tga2 tga5 tga6 mutants. We found that TGAs directly activate RBOHD and RBOHF expression and that RipAB inhibits this through interfering with the recruitment of RNA polymerase II. These results suggest that TGAs are the bona fide and major virulence targets of RipAB, which disrupts SA signaling by inhibiting TGA activity to achieve successful infection.

• Authors: Peipei Qi, Mengling Huang, Xuehan Hu, Ying Zhang, Ying Wang, Pengyue Li, Shiyun Chen, Dan Zhang, Sen Cao, Wanting Zhu, Jiatao Xie, Jiasen Cheng, Yanping Fu, Daohong Jiang, Xiao Yu, Bo Li
• Journal: The Plant cell (Plant Cell) Vol. 34 Issue 5 Pg. 1666-1683 (04 26 2022) ISSN: 1532-298X [Electronic] England
• PMID: 35043960 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © American Society of Plant Biologists 2022. All rights reserved. For permissions, please email: [email protected].

Chemical References

• Basic-Leucine Zipper Transcription Factors
• Reactive Oxygen Species
• TGA4 protein, Arabidopsis
• Transcription Factors
• Salicylic Acid

Topics

• Arabidopsis (metabolism)
• Basic-Leucine Zipper Transcription Factors (metabolism)
• Solanum lycopersicum (genetics, metabolism)
• Plant Diseases (microbiology)
• Ralstonia solanacearum (genetics, metabolism)
• Reactive Oxygen Species (metabolism)
• Salicylic Acid (metabolism)
• Transcription Factors (genetics, metabolism)