Expression of phytochelatin synthase from aquatic macrophyte Ceratophyllum demersum L. enhances cadmium and arsenic accumulation in tobacco
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Phytochelatin synthase (PCS), the key enzyme involved in heavy metal detoxification and accumulation has been used from various sources to develop transgenic plants for the purpose of phytoremediation. However, some of the earlier studies provided contradictory results. Most of the PCS genes were isolated from plants that are not potential metal accumulators. In this study, we have isolated PCS gene from Ceratophyllum demersum cv. L. (CdPCS1), a submerged rootless aquatic macrophyte, which is considered as potential accumulator of heavy metals. The CdPCS1 cDNA of 1,757 bp encodes a polypeptide of 501 amino acid residues and differs from other known PCS with respect to the presence of a number of cysteine residues known for their interaction with heavy metals. Complementation of cad1-3 mutant of Arabidopsis deficient in PC (phytochelatin) biosynthesis by CdPCS1 suggests its role in the synthesis of PCs. Transgenic tobacco plants expressing CdPCS1 showed several-fold increased PC content and precursor non-protein thiols with enhanced accumulation of cadmium (Cd) and arsenic (As) without significant decrease in plant growth. We conclude that CdPCS1 encodes functional PCS and may be part of metal detoxification mechanism of the heavy metal accumulating plant C. demersum.
Heterologous expression of PCS gene from C. demersum complements Arabidopsis cad1-3 mutant and leads to enhanced accumulation of Cd and As in transgenic tobacco.
KeywordsArsenic Aquatic macrophyte Cadmium Ceratophyllum demersum Phytochelatin synthase Transgenic tobacco
cad1-3 mutant plants transformed with CdPCS1 construct
We thank Prof. Christopher Cobbett (University of Melbourne, Australia) for providing cad1-3 seeds. DS, RK and SM acknowledge Council of Scientific and Industrial Research, Govt. of India for Senior Research Fellowships. The authors are grateful to the Department of Biotechnology, New Delhi for providing financial support to carry out the work.
- Mendoza-Cózatl DG, Butko E, Springer F, Torpey JW, Komives EA, Kehr J (2008) Identification of high levels of phytochelatins, glutathione and cadmium in the phloem sap of Brassica napus. A role for thiol-peptides in the long-distance transport of cadmium and the effect of cadmium on iron translocation. Plant J 54:249–259PubMedCrossRefGoogle Scholar
- Pomponi M, Censi V, Di Girolamo V, De Paolis A, di Toppi LS, Aromolo R, Costantino P, Cardarelli M (2006) Overexpression of Arabidopsis phytochelatin synthase in tobacco plants enhances Cd2+ tolerance and accumulation but not translocation to the shoot. Planta 223:180–190PubMedCrossRefGoogle Scholar
- Rea PA (2012) Phytochelatin synthase: of a protease a peptide polymerase made. Physiol Plant. doi: 10.1111/j.1399-3054.2012.01571.x
- Sambrook J, Fritsch EF, Maniatis T (1989) Molecular cloning: a laboratory manual. Cold Spring Harbor Laboratory Press, New YorkGoogle Scholar
- Sarry JE, Kuhn L, Ducruix C, Lafaye A, Junot C, Hugouvieux V, Jourdain A, Bastien O, Fievet JB, Vailhen D, Amecraz B, Moulin C, Ezan E, Garin J, Bourguignon J (2006) The early responses of Arabidopsis thaliana cells to Cadmium exposure explored by protein and metabolite profiling analysis. Proteomics 6:2180–2198PubMedCrossRefGoogle Scholar
- Tsuji N, Nishikori S, Iwabe O, Matsumoto S, Shiraki K, Miyasaka H, Takagi M, Miyamoto K, Hirata K (2005) Comparative analysis of the two-step reaction catalyzed by prokaryotic and eukaryotic phytochelatin synthase by an ion pair liquid chromatography assay. Planta 222:181–191PubMedCrossRefGoogle Scholar
- Vatamaniuk OK, Mari S, Lang A, Chalasani S, Demkiv L, Rea PA (2004) Phytochelatin synthase, a dipeptidyltransferase that undergoes multisite acylation with γ-glutamycysteine during catalysis. Stoichiometric and site-directed mutagenic analysis of Arabidopsis thaliana PCS1-catalyzed phytochelatin synthesis. J Biol Chem 279:22449–22460PubMedCrossRefGoogle Scholar
- Wojas S, Clemens S, Hennig J, Sklodowska A, Kopera E, Schat H, Bal W, Antosiewicz DM (2008) Overexpression of phytochelatin synthase in tobacco: distinctive effects of AtPCS1 and CePCS genes on plant response to cadmium. J Exp Bot 92:1–15Google Scholar