TGA Transcription Factors

TGA transcription factors belong to the group of bZIP transcription factors which are found in all eukaryotes. TGA factors bind specifically to variants of the palindrome TGACGTCA. Two of these sequences separated by 4 bps are called an activation sequence-1 (as-1).

The family of TGA factors has 10 members in the model plant Arabidopsis thaliana.
The tga2 tga5 tga6 mutant which lacks the three closely related clade II TGA factors displays the following deficiencies.

1. It does not activate the important salicylic acid-dependent immune response "Systemic acquired resistance". Salicylic acid is a plant defense hormone that is synthesized after attack with pathogens that exploit living plant cells (biotrophs). To confer systemic acquired resistance, TGA factors interact with the salicylic acid-activated transcriptional co-activator NPR1 (Zhang et al., 1999; Zhang et al., 2003).

2. It does not activate the important jasmonic acid/ethylene-dependent immune response which is effective against pathogens that kill host cells (necrotrophs) (Zander et al., 2010).

3. It does not activate many genes of the detoxification program upon treatment with toxic chemicals (Fode et al., 2008).

• Identification of target genes of clade I TGA factors.
• Redox-modification of Clade I TGA factors and TGA-interacting proteins by glutaredoxins ROXY18, ROXY19 and ROXY9.
• Activation of TGA-dependent detoxification genes by xenobiotics.