engleski

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

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 tran- scription factors TGACG-BINDING FACTOR 1 and 4 (TGA1 and TGA4, respectively). Theyactivate expression of SYSTEMIC ACQUIRED RESISTANCE DEFICIENT1, the gene product ofwhich regulates the key SA biosynthesis gene ISOCHORISMATE SYNTHASE 1.Since TGA1 interacts with the SA receptor NONEXPRESSOR OF PATHOGENESIS-RELATEDGENES 1 (NPR1) in a redox-dependent manner and since the redox state of TGA1 is altered inSA-treated plants, TGA1 was assumed to play a role in the NPR1-dependent signaling cas-cade. Here, we identified 193 out of 2090 SA-induced genes that require TGA1/TGA4 formaximal expression after SA treatment. One robustly TGA1/TGA4-dependent gene encodesfor the SA hydroxylase DOWNY MILDEW RESISTANT 6-LIKE OXYGENASE 1, suggesting anadditional regulatory role of TGA1/TGA4 in SA catabolism.Expression of TGA1/TGA4-dependent genes in mock/SA-treated or Pseudomonas-infectedplants was rescued in the tga1 tga4 double mutant after introduction of a mutant genomicTGA1 fragment encoding a TGA1 protein without any cysteines. Thus, the functional signifi-cance of the observed redox modification of TGA1 in SA-treated tissues remains enigmatic

Arabidopsis thaliana ; defense responses ; NPR1 ; redox regulation ; salicylic acid ; TGA transcription factors

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