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

Abstract

Summary• A bZIP transcription factor from Brassica juncea (BjCdR15) was isolated by the cDNA-amplified fragment length polymorphism technique after cadmium treatment. Sequence analysis indicated high similarity between BjCdR15 and Arabidopsis TGA3. In Arabidopsis, TGA3 transcription is also induced by cadmium; hence, we investigated whether BjCdR15 is involved in cadmium tolerance and whether it can functionally replace TGA3 protein in Arabidopsis tga3-2 mutant plants.• BjCdR15 expression was detected mainly in the epidermis and vascular system of cadmium-treated plants, and increased in roots and leaves after cadmium treatment. The overexpression of BjCdR15 in Arabidopsis and tobacco enhanced cadmium tolerance: overexpressing plants showed high cadmium accumulation in shoots. Conversely, Arabidopsis tga3-2 mutant plants showed high cadmium content in 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 to shoot was restored and these plants showed an increased cadmium content in shoots compared with all other assays. In addition, BjCdR15 ⁄ TGA3 regulated the synthesis of phytochelatin synthase and the expression of several metal transporters.• The results indicate that BjCdR15 ⁄ TGA3 transcription factors play a crucial role in the regulation of cadmium uptake by roots and in its long-distance root to shoot transport. BjCdR15 ⁄ TGA3 may thus be considered as useful candidates for potential biotechnological applications in the phytoextraction of cadmium from polluted soils.

Overexpression of AtATM3 in Brassica juncea confers enhanced heavy metal tolerance and accumulation

“…BjMTP1 is a transporter localized to the plasma membrane and is involved in vacuolar sequestration of heavy metals (Muthukumar et al 2007). BjCdR15 plays a crucial role in the regulation of Cd uptake by roots and the long-distance root to shoot Cd transport (Farinati et al 2010). Catalase (BjCAT3) was reported as an important antioxidant enzyme which prevent plant from Cd-induced oxidative stress caused by reactive oxygen species (Guan et al 2009).…”

“…In recent years, several genes and protein families have been characterized in relation to their role in heavy metal tolerance and accumulation, including metal transporters, such as ATP-binding cassette (ABC) transporters (Rea 2007), the P 1B -type subfamily of P-type ATPases (Verret et al 2004;Mills et al 2005), the natural resistance-associated macrophage protein (Nramp) family (Belouchi et al 1997;Curie et al 2000), the zinc/iron-regulated transporter protein (ZIP) family (Farinati et al 2010), ABC transporters of the mitochondria (ATM) (Kushnir et al 2001;Kim et al 2006), the cation diffusion facilitator (CDF) family (Kim et al 2004), multidrug resistance-associated proteins (MRPs) (Klein et al 2006), the copper transporter (COPT) family (Miyabe et al 2001), pleiotropic drug resistance (PDR) transporters (Lee et al 2005;Kim et al 2007), the Ca 2? -sensitive cross complementor 1 (CCC1) family (Hirchi et al 2000), the iron-regulated protein (IREG) family (Schaaf et al 2006), and the yellow-stripe 1-like (YSL) subfamily of the oligopeptide transporter (OPT) superfamily (Kramer et al 2007).…”

The uptake and bioaccumulation of heavy metals by food plants, their effects on plants nutrients, and associated health risk: a review

“…Phytochelatins play a key role in metal detoxification (Cobbett 2000). The Brassica juncea (BjCdR15) and Arabidopsis TGA3 are good tolerants to high metal concentrations because of the mechanisms such as the regulation of synthesis of phytochelatin by BjCdR15/ TGA3 (Farinati et al 2010). Similarly, different genes are involved in metal tolerance by mediating metal-glutathione conjugate transport .…”

Bean Metal-Responsive Element-Binding Transcription Factor Confers Cadmium Resistance in Tobacco

“…Wheat (Triticum aestivum) heat shock transcription factorA4a and its rice ortholog confer Cd tolerance in transgenic rice seedlings by regulating MT gene expression (Shim et al, 2009). Indian mustard Brassica juncea Cd-regulated gene15 and its Arabidopsis ortholog TGA3 improve Cd tolerance in transgenic Arabidopsis and tobacco plants through the regulation of Cd uptake by roots (Farinati et al, 2010). In Arabidopsis plants, co-overexpression of basic helix-loophelix (bHLH) transcription factor bHLH29 with bHLH38 or bHLH39 can enhance Cd tolerance via increasing Cd sequestration in roots (Wu et al, 2012).…”