Salicylic acid-dependent and -independent impact of an RNA-binding protein on plant immunity.

Abstract

Plants overexpressing the RNA-binding protein AtGRP7 (AtGRP7-ox plants) constitutively express the PR-1 (PATHOGENESIS-RELATED-1), PR-2 and PR-5 transcripts associated with salicylic acid (SA)-mediated immunity and show enhanced resistance against Pseudomonas syringae pv. tomato (Pto) DC3000. Here, we investigated whether the function of AtGRP7 in plant immunity depends on SA. Endogenous SA was elevated fivefold in AtGRP7-ox plants. The elevated PR-1, PR-2 and PR-5 levels were eliminated upon expression of the salicylate hydroxylase nahG in AtGRP7-ox plants and elevated PR-1 levels were suppressed by sid (salicylic acid deficient) 2-1 that is impaired in SA biosynthesis. RNA immunoprecipitation showed that AtGRP7 does not bind the PR-1 transcript in vivo, whereas it binds PDF1.2. Constitutive or inducible AtGRP7 overexpression increases PR-1 promoter activity, indicating that AtGRP7 affects PR-1 transcription. In line with this, the effect of AtGRP7 on PR-1 is suppressed by npr (non-expressor of PR genes) 1. Whereas AtGRP7-ox plants restricted growth of Pto DC3000 compared with wild type (wt), sid2-1 AtGRP7-ox plants allowed more growth than AtGRP7-ox plants. Furthermore, we show an enhanced hypersensitive response triggered by avirulent Pto DC3000 (AvrRpt2) in AtGRP7-ox compared with wt. In sid2-1 AtGRP7-ox, an intermediate phenotype was observed. Thus, AtGRP7 has both SA-dependent and SA-independent effects on plant immunity.

• Authors: Christian Hackmann, Christin Korneli, Magdalene Kutyniok, Tino Köster, Matthias Wiedenlübbert, Caroline Müller, Dorothee Staiger
• Journal: Plant, cell & environment (Plant Cell Environ) Vol. 37 Issue 3 Pg. 696-706 (Mar 2014) ISSN: 1365-3040 [Electronic] United States
• PMID: 23961939 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2013 John Wiley & Sons Ltd.

Chemical References

• ATGRP7 protein, Arabidopsis
• Arabidopsis Proteins
• Glucosides
• RNA, Messenger
• RNA-Binding Proteins
• Salicylates
• salicylic acid glucoside
• Green Fluorescent Proteins
• Mixed Function Oxygenases
• salicylate 1-monooxygenase
• Glucuronidase
• Intramolecular Transferases
• isochorismate synthase
• Salicylic Acid

Topics

• Arabidopsis (genetics, immunology, metabolism, microbiology)
• Arabidopsis Proteins (genetics, metabolism)
• Disease Resistance (drug effects, genetics)
• Gene Expression Regulation, Plant (drug effects)
• Glucosides (pharmacology)
• Glucuronidase (metabolism)
• Green Fluorescent Proteins (metabolism)
• Intramolecular Transferases (metabolism)
• Mixed Function Oxygenases (metabolism)
• Plant Diseases (genetics, microbiology)
• Plant Immunity (drug effects, genetics)
• Plants, Genetically Modified
• Protein Binding (drug effects, genetics)
• Pseudomonas syringae (drug effects, pathogenicity)
• RNA, Messenger (genetics, metabolism)
• RNA-Binding Proteins (genetics, metabolism)
• Salicylates (pharmacology)
• Salicylic Acid (pharmacology)
• Substrate Specificity (drug effects, genetics)
• Transcription, Genetic (drug effects)
• Virulence (drug effects, genetics)