The Arabidopsis Cytosolic Thioredoxin h5 Gene Induction by Oxidative Stress and Its W-Box-Mediated Response to Pathogen Elicitor

The AtTRXh5 protein belongs to the cytosolic thioredoxins h family that, in Arabidopsis, contains eight members showing very distinct patterns and levels of expression. Here, we show that the AtTRXh5 gene is up-regulated during wounding, abscission, and senescence, as well as during incompatible interactions with the bacterial pathogen Pseudomonas syringae. By electrophoretic mobility shift assays, a binding activity on a W-box in the AtTRXh5 promoter region was found induced by treatments with the P. syringae-derived elicitor peptide flg22, suggesting that a WRKY transcription factor controls AtTRXh5 induction upon elicitor treatment. Remarkably, AtTRXh5 was upregulated in plants overexpressing WRKY6. More generally, AtTRXh5 is induced in response to oxidative stress conditions. Collectively, our data indicate a possible implication of the cytosolic thioredoxin AtTRXh5 in response to pathogens and to oxidative stresses. In addition, this regulation is unique to AtTRXh5 among the thioredoxin h family, arguing in favor of a speciation rather than to a redundancy of the members of this multigenic family.