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United States Department of Agriculture

Agricultural Research Service

Title: RAR1, a Central Player in Plant Immunity, is Targeted by Pseudomonas syringae Effector AvrB)

Author
item Shang, Yulei
item Li, Xinyan
item Cui, Haitao
item He, Ping
item Thilmony, Roger
item Chintamanani, Satya
item Zwiesler-vollick, Julie
item Gopalan, Suresh
item Tang, Xiaoyan
item Zhou, Jian-min

Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/24/2006
Publication Date: 12/5/2006
Citation: Shang, Y., Li, X., Cui, H., He, P., Thilmony, R.L., Chintamanani, S., Zwiesler-Vollick, J., Gopalan, S., Tang, X., Zhou, J. 2006. Rar1, a central player in plant immunity, is targeted by pseudomonas syringae effector avrb. Proceedings of the National Academy of Sciences. PNAS vol. 103 no. 50 pg. 19200-19205

Interpretive Summary: Plant disease causes significant crop losses and our understanding of how plant pathogens cause disease is limited. This research demonstrates how a protein from a bacterial pathogen weakens the ability of the host plant to defend itself from disease. In particular the relationship between this pathogen protein and a plant protein required for resistance is investigated. This research demonstrates that a plant protein involved in pathogen resistance is also a target for a bacterial protein that impairs host defenses and promotes the ability of the pathogen to cause disease.

Technical Abstract: Pathogenic bacterial effectors suppress Pathogen-Associated Molecular Pattern (PAMP)-triggered host immunity, thereby promoting parasitism. In the presence of cognate resistance genes, it is proposed that plants detect the virulence activity of bacterial effectors and trigger a defense response, referred to here as effector-triggered immunity. However, the link between effector virulence and effector-triggered immunity at the molecular level is unknown. Here, we show that the Pseudomonas syringae effector AvrB suppresses PAMP-triggered immunity through RAR1, a co-chaperone of HSP90 required for effector-triggered immunity. AvrB expressed in plants lacking the cognate resistance gene RPM1 suppresses cell wall defense induced by the flagellar peptide flg22, a well-known PAMP, and promotes the growth of nonpathogenic bacteria in a RAR1-dependent manner. rar1 mutants display enhanced cell wall defense in response to flg22, indicating that RAR1 negatively regulates PAMP-triggered immunity. Furthermore, coimmunoprecipitation experiments indicated that RAR1 and AvrB interact in the plant. The results demonstrate that RAR1 molecularly links PAMP-triggered immunity, the effector virulence, and effector-triggered immunity. The study supports that both pathogen virulence and plant disease resistance have evolved around the PAMP-triggered immunity.

Last Modified: 8/24/2016
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