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 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.
Farinati
Silvia
S
Dipartimento di Biotecnologie, Università degli Studi di Verona, Verona, Italy.
DalCorso
Giovanni
G
Varotto
Serena
S
Furini
Antonella
A
D000222:Adaptation, Physiological / Q000187:drug effects; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D018533:Biomass; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology; D002734:Chlorophyll / Q000378:metabolism; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009149:Mustard Plant / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism*; D030821:Plants, Genetically Modified; D021381:Protein Transport / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D026901:Membrane Transport Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; C087770:TGA3 protein, Arabidopsis; D002104:Cadmium; D002734:Chlorophyll