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Research article - Peer-reviewed, 2022

The TGA Transcription Factors from Clade II Negatively Regulate the Salicylic Acid Accumulation in Arabidopsis

Fonseca, Alejandro; Urzua, Tomas; Jelenska, Joanna; Sbarbaro, Christopher; Seguel, Aldo; Duarte, Yorley; Greenberg, Jean T.; Holuigue, Loreto; Blanco-Herrera, Francisca; Herrera-Vasquez, Ariel


Salicylic acid (SA) is a hormone that modulates plant defenses by inducing changes in gene expression. The mechanisms that control SA accumulation are essential for understanding the defensive process. TGA transcription factors from clade II in Arabidopsis, which include the proteins TGA2, TGA5, and TGA6, are known to be key positive mediators for the transcription of genes such as PR-1 that are induced by SA application. However, unexpectedly, stress conditions that induce SA accumulation, such as infection with the avirulent pathogen P. syringae DC3000/AvrRPM1 and UV-C irradiation, result in enhanced PR-1 induction in plants lacking the clade II TGAs (tga256 plants). Increased PR-1 induction was accompanied by enhanced isochorismate synthase-dependent SA production as well as the upregulation of several genes involved in the hormone's accumulation. In response to avirulent P. syringae, PR-1 was previously shown to be controlled by both SA-dependent and -independent pathways. Therefore, the enhanced induction of PR-1 (and other defense genes) and accumulation of SA in the tga256 mutant plants is consistent with the clade II TGA factors providing negative feedback regulation of the SA-dependent and/or -independent pathways. Together, our results indicate that the TGA transcription factors from clade II negatively control SA accumulation under stress conditions that induce the hormone production. Our study describes a mechanism involving old actors playing new roles in regulating SA homeostasis under stress.


salicylic acid; TGA transcription factors; Pseudomonas syringae; AvrRPM1; UV-C; tga256; PR-1; pathogenesis-related 1

Published in

International Journal of Molecular Sciences
2022, volume: 23, number: 19, article number: 11631
Publisher: MDPI

Authors' information

Millennium Institute for Integrative Biology
Swedish University of Agricultural Sciences, Department of Plant Biology
Urzua, Tomas
Millennium Institute for Integrative Biology
Jelenska, Joanna
University of Chicago
Sbarbaro, Christopher
Universidad Andres Bello
Seguel, Aldo
Pontificia Universidad Catolica de Chile
Duarte, Yorley
Universidad Andres Bello
Greenberg, Jean T.
University of Chicago
Holuigue, Loreto
Pontificia Universidad Catolica de Chile
Blanco-Herrera, Francisca
Universidad Andres Bello
Herrera-Vasquez, Ariel
Universidad Andres Bello

Associated SLU-program

SLU Network Plant Protection

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