Transcriptional Control of @entity71522 GRXC9 Expression by a @entity3785 -Dependent and XXXX -Independent Pathway in @entity958 .

@entity3785 @entity71522 @entity71524 @entity958 @entity71525 @entity14349 @entity71523
UNASSIGNED: @entity3785 (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 @entity71522 from @entity958 , is an SA-responsive gene induced early and transiently by an @entity14349 -independent pathway. Here, we address the mechanism involved in this SA-dependent pathway, using GRXC9 as a model gene. We first established that GRXC9 expression is induced by UVB exposure through this pathway, validating its activation in a physiological stress condition. GRXC9 promoter analyses indicate that SA controls gene transcription through two activating sequence-1 (as-1)-like elements located in its proximal region. @entity71523 and @entity71524 , but not @entity71525 , are constitutively bound to this promoter region. Accordingly, the transient recruitment of RNA polymerase II to the GRXC9 promoter, as well as the transient accumulation of gene transcripts detected in SA-treated WT plants, was abolished in a knockout mutant for the TGA class II factors. We conclude that constitutive binding of @entity71523 is essential for controlling GRXC9 expression, while binding of @entity71524 in a lesser extent contributes to this regulation. Finally, overexpression of GRXC9 indicates that the GRXC9 protein negatively controls its own gene expression, forming part of the complex bound to the as-1-containing promoter region. These findings are integrated in a model that explains how SA controls transcription of GRXC9 in the context of the defense response to stress.
