Dipartimento di Biotecnologie, Università degli Studi di Verona, Verona, Italy.
New Phytol. 2010 Mar;185(4):964-78. doi: 10.1111/j.1469-8137.2009.03132.x. Epub 2009 Dec 21.
*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.
甘蓝型油菜(BjCdR15)的 bZIP 转录因子通过镉处理后的 cDNA 扩增片段长度多态性技术分离得到。序列分析表明,BjCdR15 与拟南芥 TGA3 之间具有高度相似性。在拟南芥中,TGA3 转录也受到镉的诱导;因此,我们研究了 BjCdR15 是否参与镉耐受,以及它是否可以在拟南芥 tga3-2 突变体植物中替代 TGA3 蛋白。BjCdR15 的表达主要在镉处理植物的表皮和维管束系统中检测到,在镉处理后在根和叶中增加。BjCdR15 在拟南芥和烟草中的过表达增强了镉耐受性:过表达植物在地上部分表现出高镉积累。相反,拟南芥 tga3-2 突变体植物在根部表现出高镉含量并抑制其向地上部分的转运。我们证明了 BjCdR15 可以替代 TGA3:在 35S::BjCdR15-tga3-2 植物中,镉从根部到地上部分的长距离运输得到恢复,这些植物在地上部分的镉含量与所有其他试验相比均增加。此外,BjCdR15/TGA3 调节了植物螯合肽合酶的合成和几种金属转运蛋白的表达。结果表明,BjCdR15/TGA3 转录因子在根吸收镉和将其从根部长距离运输到地上部分的过程中发挥关键作用。因此,BjCdR15/TGA3 可以被认为是在从污染土壤中植物提取镉的潜在生物技术应用中的有用候选物。