tga1

TGA1 is a gene in the model plant species Arabidopsis thaliana that encodes a transcription factor of the TGA family, a subgroup of basic leucine zipper (bZIP) proteins. TGA1 proteins bind promoter elements containing the TGACG motif and regulate transcription in response to signaling cues.

Function: TGA1 participates in the plant's defense signaling, particularly the salicylic acid (SA) pathway. It forms DNA-binding dimers and interacts with NPR1 (nonexpressor of pathogenesis-related genes 1) in the nucleus to activate transcription of defense-related genes, including PR genes.

Role in defense: Genetic analyses show TGA1 contributes to basal and SA-induced resistance against bacterial pathogens such as Pseudomonas syringae. In tga1 mutants, SA-responsive gene induction is attenuated; in combination with related TGA factors, regulation is more pronounced.

Expression and regulation: TGA1 expression is modulated by pathogen challenge and SA treatment. The protein localizes to the nucleus and can be regulated by redox state through NPR1 interaction.

Family context: TGA1 is one member of a plant TGA transcription factor family (including TGA2–TGA6 in Arabidopsis) with overlapping functions. Redundancy among family members often masks single-gene phenotypes; double or higher-order mutants reveal more severe defects in defense signaling. Beyond defense, TGA factors can influence development and responses to abiotic stress in some contexts.

In research, TGA1 is cited as a key component of SA-mediated transcriptional reprogramming and NPR1-dependent defense, and is used to study the molecular details of promoter recognition, protein–protein interactions, and systemic acquired resistance in plants.