The Brassica juncea BjCdR15, an ortholog of Arabidopsis TGA3, is a regulator of cadmium uptake, transport and accumulation in shoots and confers cadmium tolerance in transgenic plants.

• A bZIP transcription factor from Brassica juncea (BjCdR15) was isolated by thecDNA-amplified fragment length polymorphism technique after cadmium treatment.Sequence analysis indicated high similarity between BjCdR15 and ArabidopsisTGA3. In Arabidopsis, TGA3 transcription is also induced by cadmium;hence, we investigated whether BjCdR15 is involved in cadmium tolerance andwhether it can functionally replace TGA3 protein in Arabidopsis tga3-2 mutantplants.• BjCdR15 expression was detected mainly in the epidermis and vascular systemof cadmium-treated plants, and increased in roots and leaves after cadmium treatment.The overexpression of BjCdR15 in Arabidopsis and tobacco enhanced cadmiumtolerance: overexpressing plants showed high cadmium accumulation inshoots. Conversely, Arabidopsis tga3-2 mutant plants showed high cadmium contentin roots and inhibition of its transport to the shoot.• We demonstrated that BjCdR15 can functionally replace TGA3: in 35S::BjCdR15-tga3-2 plants, the long-distance transport of cadmium from root toshoot was restored and these plants showed an increased cadmium content inshoots compared with all other assays. In addition, BjCdR15 ⁄ TGA3 regulatedthe synthesis of phytochelatin synthase and the expression of several metaltransporters.• The results indicate that BjCdR15 ⁄ TGA3 transcription factors play a crucial rolein the regulation of cadmium uptake by roots and in its long-distance root to shoottransport. BjCdR15 ⁄ TGA3 may thus be considered as useful candidates for potentialbiotechnological applications in the phytoextraction of cadmium from pollutedsoils.