Promotion of metal accumulation in nodule of Astragalus sinicus by the expression of the iron-regulated transporter gene in Mesorhizobium huakuii subsp. rengei B3

Akiko Ike, Rutchadaporn Sriprang, Hisayo Ono, Yoshikatsu Murooka, Mitsuo Yamashita

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Toxic metal contamination in agricultural fields is an important worldwide problem. In previous studies, we developed a bioremediation system based on the symbiosis between Astragalus sinicus and the recombinant rhizobium, Mesorhizobium huakuii subsp. rengei B3 developed by overexpressing a synthetic tetrameric metallothionein gene (MTL4) and cDNA encoding the phytochelatin synthase from Arabidopsis thaliana (AtPCS). To promote the transport of metals into the nodules of the rhizobium and the accumulation of metals, the iron-regulated transporter 1 gene from A. thaliana (AtIRT1) was introduced into recombinant strain B3 containing MTL4 or AtPCS in its chromosome. The fused AtIRT1-alkaline phosphatase was expressed in the free-living recombinant rhizobium and the nodule of A. sinicus. The recombinant strain B3 carrying AtIRT1 showed a higher Cd sensitivity and a higher amount of Cd accumulated in free-living culture than the wild-type strain B3. When the recombinant strain B3 established symbiosis with A. sinicus, the introduction of AtIRT1 in the recombinant strain B3 advantaged the accumulation of Cu and As in the nodules of A. sinicus, compared with that of Cd and Zn.

Original languageEnglish
Pages (from-to)642-648
Number of pages7
JournalJournal of Bioscience and Bioengineering
Issue number6
Publication statusPublished - 2008 Jun 1



  • Leguminous plant
  • Rhizobium
  • heavy metals
  • iron-regulated transporter 1
  • symbiosis

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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