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Expression of the bacterial heavy metal transporter MerC fused with a plant SNARE, SYP121, in Arabidopsis thaliana increases cadmium accumulation and tolerance

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The bacterial merC gene from the Tn21-encoded mer operon is a potential molecular tool for improving the efficiency of metal phytoremediation. Arabidopsis SNARE molecules, including SYP111, SYP121, and AtVAM3 (SYP22), were attached to the C-terminus of MerC to target the protein to various organelles. The subcellular localization of transiently expressed GFP-fused MerC-SYP111, MerC-SYP121, and MerC-AtVAM3 was examined in Arabidopsis suspension-cultured cells. We found that GFP-MerC-SYP111 and GFP-MerC-SYP121 localized to the plasma membrane, whereas GFP-AtVAM3 localized to the vacuolar membranes. These results demonstrate that SYP111/SYP121 and AtVAM3 target foreign molecules to the plasma membrane and vacuolar membrane, respectively. To enhance the efficiency and potential of plants to sequester and accumulate cadmium from contaminated sites, transgenic Arabidopsis plants expressing MerC, MerC-SYP111, MerC-SYP121, or MerC-AtVAM3 were generated. The transgenic plants that expressed MerC, MerC-SYP121, or MerC-AtVAM3 appeared to be normal, whereas the transgenic that expressed MerC-SYP111 exhibited severe growth defects. The transgenic plants expressing merC-SYP121 were more resistant to cadmium than the wild type and accumulated significantly more cadmium. Thus, the expression of MerC-SYP121 in the plant plasma membrane may provide an ecologically compatible approach for the phytoremediation of cadmium pollution.

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Green fluorescent protein


Reverse transcription-polymerase chain reaction


Soluble N-ethyl-maleimide-sensitive factor attachment protein receptor


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We are grateful to Dr. M. Sugiyama of The University of Tokyo for the gift of Arabidopsis thaliana Columbia. We thank Dr. S. Uraguchi of The University of Tokyo for his valuable advice. We also thank Miss. A. Nakagawa, Miss. C. Ozawa, Miss. Y. Hachiya and Mr. H. Tojo for their technical assistance. This work was supported in part by a Grant-in-Aid for Scientific Research (C) (No. 21510088) to M.K. from the Ministry of Education, Science and Culture, Japan. This work was also supported in part by a Kitasato University Research Grant for Young Researchers to M.K.

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Correspondence to Masako Kiyono.

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Kiyono, M., Oka, Y., Sone, Y. et al. Expression of the bacterial heavy metal transporter MerC fused with a plant SNARE, SYP121, in Arabidopsis thaliana increases cadmium accumulation and tolerance. Planta 235, 841–850 (2012). https://doi.org/10.1007/s00425-011-1543-4

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  • Bacterial heavy metal transport
  • Cadmium
  • MerC
  • Phytoremediation