title: 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: Department of Molecular Cell Physiology, Bielefeld University, Universitätsstraße 25, D-33615, Bielefeld, Germany; Institute for Genome Research and Systems Biology, CeBiTec, Bielefeld University, Universitätsstraße 25, D-33615, Bielefeld, Germany.
authors: Christian
authors: C
authors: Hackmann
authors: Christin
authors: C
authors: Korneli
authors: Magdalene
authors: M
authors: Kutyniok
authors: Tino
authors: T
authors: Köster
authors: Matthias
authors: M
authors: Wiedenlübbert
authors: Caroline
authors: C
authors: Müller
authors: Dorothee
authors: D
authors: Staiger
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060467:Disease Resistance / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005960:Glucosides / Q000494:pharmacology; D005966:Glucuronidase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D019751:Intramolecular Transferases / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D057865:Plant Immunity / Q000187:drug effects* / Q000235:genetics; D030821:Plants, Genetically Modified; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D044224:Pseudomonas syringae / Q000187:drug effects / Q000472:pathogenicity; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012459:Salicylates / Q000494:pharmacology; D020156:Salicylic Acid / Q000494:pharmacology*; D013379:Substrate Specificity / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects; D014774:Virulence / Q000187:drug effects / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D005960:Glucosides; D005966:Glucuronidase; D049452:Green Fluorescent Proteins; D019751:Intramolecular Transferases; D006899:Mixed Function Oxygenases; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012459:Salicylates; D020156:Salicylic Acid; C118496:GRP7 protein, Arabidopsis; C084746:salicylic acid glucoside; C022619:salicylate 1-monooxygenase; C058486:isochorismate synthase
keywords: NPR1; glycine-rich RNA-binding protein; pathogenesis-related genes