Cloning and characterization of a Phragmites australis phytochelatin synthase (PaPCS) and achieving Cd tolerance in tall fescue.

Cuizhu Zhao,Jin Xu,Fengning Xiang,Peng Wang,Qiang Li,Shuo Li,Manuel Reigosa

doi:10.1371/journal.pone.0103771

Abstract

The production of phytochelatins (PCs) provides an important means for plants to achieve tolerance to cadmium (Cd) toxicity. A reed gene encoding PC synthase (PaPCS) was isolated and its function tested through its heterologous expression in a strain of yeast sensitive to Cd. Subsequently, the Cd sensitive and high biomass accumulating species tall fescue was transformed either with PaPCS or PaGCS (a glutamyl cysteine synthetase gene of reed) on their own (single transformants), or with both genes together in the same transgene cassette (double transformant). The single and double transformants showed greater Cd tolerance and accumulated more Cd and PC than wild type plants, and their Cd leaf/root ratio content was higher. The ranking in terms of Cd and PC content for the various transgenic lines was double transformants>PaGCS single transformants>PaPCS single transformants>wild type. Thus PaGCS appears to exert a greater influence than PaPCS over PC synthesis and Cd tolerance/accumulation. The double transformant has interesting potential for phytoremediation.

Highlights

Heavy metal pollution caused by a combination of natural leaching and anthropogenic activity is becoming a significant environmental problem
We have previously shown that the c-glutamyl cysteine synthetase (c-GCS) glutamyl cysteine synthetase gene of P. australis (PaGCS) is a key component of the species’ heavy metal tolerance, and that when this gene is expressed in the fast-growing species Agrostis palustris, tolerance to Cd toxicity is measurably enhanced [26]
In the present study we further explored the potential of P. australis as a donor of phytoremediation genes by testing the effect of expressing Phragmites australis Phytochelatin Synthase (PaPCS) and/or PaGCS in tall fescue

Summary

Introduction

Heavy metal pollution caused by a combination of natural leaching and anthropogenic activity is becoming a significant environmental problem. The optimal phytoremediating plant needs to be highly productive in terms of biomass and efficient in terms of accumulation of heavy metals [4,5]. One such species is the reed Phragmites australis (Cav.) Trin. It has been proposed that an effective approach could be based on the engineering of heavy metal accumulation and tolerance into a species already recognized as being an effective biomass producer [10,11,12]. A number of genes involved in the uptake of and tolerance to heavy metals have been identified, and some have already been successfully transferred into plants [13–

Methods

Results

Conclusion