title: Transcriptional Control of GlutaredoxinGRXC9Expression by a Salicylic Acid-Dependent and NPR1-Independent Pathway inArabidopsis.
abstract: Salicylic acid (SA) is a key hormone that mediates gene transcriptional reprogramming in the context of the defense response to stress.GRXC9, coding for a CC-type glutaredoxin fromArabidopsis, is an SA-responsive gene induced early and transiently by an NPR1-independent pathway. Here, we address the mechanism involved in this SA-dependent pathway, usingGRXC9as a model gene. We first established thatGRXC9expression is induced by UVB exposure through this pathway, validating its activation in a physiological stress condition.GRXC9promoter analyses indicate that SA controls gene transcription through twoactivating sequence-1(as-1)-like elements located in its proximal region. TGA2 and TGA3, but not TGA1, are constitutively bound to this promoter region. Accordingly, the transient recruitment of RNA polymerase II to theGRXC9promoter, as well as the transient accumulation of gene transcripts detected in SA-treated WT plants, was abolished in aknockoutmutant for the TGA class II factors. We conclude that constitutive binding of TGA2 is essential for controllingGRXC9expression, while binding of TGA3 in a lesser extent contributes to this regulation. Finally, overexpression ofGRXC9indicates that theGRXC9protein negatively controls its own gene expression, forming part of the complex bound to theas-1-containing promoter region. These findings are integrated in a model that explains how SA controls transcription ofGRXC9in the context of the defense response to stress.
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
authors.forename: Ariel
authors.initials: A
authors.lastname: Herrera-Vásquez
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
authors.forename: Loreto
authors.initials: L
authors.lastname: Carvallo
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
authors.forename: Francisca
authors.initials: F
authors.lastname: Blanco
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
authors.forename: Mariola
authors.initials: M
authors.lastname: Tobar
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
authors.forename: Eva
authors.initials: E
authors.lastname: Villarroel-Candia
authors.affiliation: Centro de Biotecnología y Genómica de Plantas (UPM-INIA), Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Vicente-Carbajosa
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
authors.forename: Paula
authors.initials: P
authors.lastname: Salinas
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
authors.forename: Loreto
authors.initials: L
authors.lastname: Holuigue
keywords: Glutaredoxin GRXC9 (GRX480); NPR1-independent; Salicylic acid; TGA transcription factors; as-1-like element