Redox‐active cysteines in TGACG‐BINDING FACTOR 1 (TGA1) do not play a role in salicylic acid or pathogen‐induced expression of TGA1‐regulated target genes in Arabidopsis thaliana. Issue 6 (16th June 2020)

• Record Type: Journal Article
• Authors: Budimir, Jelena; Treffon, Katrin; Nair, Aswin; Thurow, Corinnna; Gatz, Christiane
• Is Part Of: New phytologist. Volume 230:Issue 6(2021)
• Page Start: 2420
• Page End: 2432
• Publication Date: 2020-06-16
• Subjects: Arabidopsis thaliana -- defense responses -- NPR1 -- redox regulation -- salicylic acid -- TGA transcription factors; Botany -- Periodicals; 580
• DOI: 10.1111/nph.16614
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Salicylic acid (SA) is an important signaling molecule of the plant immune system. In Arabidopsis thaliana, SA biosynthesis is indirectly modulated by the closely related transcription factors TGACG‐BINDING FACTOR 1 and 4 (TGA1 and TGA4, respectively). They activate expression of SYSTEMIC ACQUIRED RESISTANCE DEFICIENT1, the gene product of which regulates the key SA biosynthesis gene ISOCHORISMATE SYNTHASE 1 . Since TGA1 interacts with the SA receptor NONEXPRESSOR OF PATHOGENESIS‐RELATED GENES 1 (NPR1) in a redox‐dependent manner and since the redox state of TGA1 is altered in SA‐treated plants, TGA1 was assumed to play a role in the NPR1‐dependent signaling cascade. Here, we identified 193 out of 2090 SA‐induced genes that require TGA1/TGA4 for maximal expression after SA treatment. One robustly TGA1/TGA4‐dependent gene encodes for the SA hydroxylase DOWNY MILDEW RESISTANT 6‐LIKE OXYGENASE 1, suggesting an additional regulatory role of TGA1/TGA4 in SA catabolism. Expression of TGA1/TGA4‐dependent genes in mock/SA‐treated or Pseudomonas ‐infected plants was rescued in the tga1 tga4 double mutant after introduction of a mutant genomic TGA1 fragment encoding a TGA1 protein without any cysteines. Thus, the functional significance of the observed redox modification of TGA1 in SA‐treated tissues remains enigmatic.