title: Expression of phytochelatin synthase from aquatic macrophyte Ceratophyllum demersum L. enhances cadmium and arsenic accumulation in tobacco.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226 001, India.
authors.forename: Devesh
authors.initials: D
authors.lastname: Shukla
authors.forename: Ravi
authors.initials: R
authors.lastname: Kesari
authors.forename: Seema
authors.initials: S
authors.lastname: Mishra
authors.forename: Sanjay
authors.initials: S
authors.lastname: Dwivedi
authors.forename: Rudra Deo
authors.initials: RD
authors.lastname: Tripathi
authors.forename: Pravendra
authors.initials: P
authors.lastname: Nath
authors.forename: Prabodh Kumar
authors.initials: PK
authors.lastname: Trivedi
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D059001:Aquatic Organisms / Q000187:drug effects / Q000201:enzymology*; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism; D001151:Arsenic / Q000378:metabolism* / Q000633:toxicity; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005816:Genetic Complementation Test; D019684:Magnoliopsida / Q000187:drug effects / Q000201:enzymology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000378:metabolism; D010802:Phylogeny; D054811:Phytochelatins / Q000378:metabolism; D030821:Plants, Genetically Modified; D016415:Sequence Alignment; D013438:Sulfhydryl Compounds / Q000378:metabolism; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D010455:Peptides; D013438:Sulfhydryl Compounds; D002104:Cadmium; D054811:Phytochelatins; D019881:Aminoacyltransferases; C093784:glutathione gamma-glutamylcysteinyltransferase; D001151:Arsenic