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Title 

Overexpression of Arabidopsis phytochelatin synthase paradoxically leads to hypersensitivity to cadmium stress

Authors 

S M LeeJae Sun MoonT S KoD PetrosP B GoldsbroughS S Korban

Publisher 

American Society of Plant Biologists

Issue Date 

2003

Citation 

Plant Physiology, vol. 131, no. 2, pp. 656-663

Keywords 

cadmiumstresseshypersensitivityarabidopsisarabidopsis proteinscadmium chlorideglutathione synthase

Abstract 

Phytochelatin (PC) plays an important role in heavy metal detoxification in plants and other living organisms. Therefore, we overexpressed an Arabidopsis PC synthase (AtPCS1) in transgenic Arabidopsis with the goal of increasing PC synthesis, metal accumulation, and metal tolerance in these plants. Transgenic Arabidopsis plants were selected, designated pcs lines, and analyzed for tolerance to cadmium (Cd). Transgenic pcs lines showed 12- to 25-fold higher accumulation of AtPCS1 mRNA, and production of PCs increased by 1.3- to 2.1-fold under 85 μM CdCl2 stress for 3 d when compared with wild-type plants. Cd tolerance was assessed by measuring root length of plants grown on agar medium containing 50 or 85 μM CdCl2. Pcs lines paradoxically showed hypersensitivity to Cd stress. This hypersensitivity was also observed for zinc (Zn) but not for copper (Cu). The overexpressed AtPCS1 protein itself was not responsible for Cd hypersensitivity as transgenic cad1-3 mutants overexpressing AtPCS1 to similar levels as those of pcs lines were not hypersensitive to Cd. Pcs lines were more sensitive to Cd than a PC-deficient Arabidopsis mutant, cad1-3, grown under low glutathione (GSH) levels. Cd hypersensitivity of pcs lines disappeared under increased GSH levels supplemented in the medium. Therefore, Cd hypersensitivity in pcs lines seems due to the toxicity of PCs as they existed at supraoptimal levels when compared with GSH levels.

ISSN 

0032-0889

Link 

http://dx.doi.org/10.1104/pp.014118

Appears in Collections

1. Journal Articles > Journal Articles

Registered Date

2019-05-02


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