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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
Author(s) -
Budimir Jelena,
Treffon Katrin,
Nair Aswin,
Thurow Corinnna,
Gatz Christiane
Publication year - 2021
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16614
Subject(s) - biology , systemic acquired resistance , arabidopsis thaliana , gene , arabidopsis , transcription factor , salicylic acid , mutant , npr1 , biochemistry , microbiology and biotechnology , genetics , medicine , heart failure , natriuretic peptide
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.