Rice-specific mitochondrial iron-regulated gene (MIR) plays an important role in iron homeostasis

Yasuhiro Ishimaru, Khurram Bashir, Masaru Fujimoto, Gynheung An, Reiko Nakanishi Itai, Nobuhiro Tsutsumi, Hiromi Nakanishi, Naoko K. Nishizawa

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44 Citations (Scopus)


Mitochondria utilize iron (Fe), but the proteins involved in mitochondrial Fe regulation are not characterized in plants. We cloned and characterized a mitochondrial iron-regulated (MIR) gene in rice involved in Fe homeostasis. MIR, when expressed in tobacco BY-2 cells, was localized to the mitochondria. MIR transcripts were greatly increased in response to Fe deficiency in roots and shoot tissue. MIR is not homologous to any known protein, as homologs were not found in the rice or Arabidopsis genome databases, or in the EST database for other organisms. Growth in the MIR T-DNA knockout rice mutant (mir) was significantly impaired compared to wild-type (WT) plants when grown under Fe-deficient or -sufficient conditions. Furthermore, mir plants accumulated more than twice the amount of Fe in shoot and root tissue compared to WT plants when grown under either Fe-sufficient or -deficient conditions. Despite the high accumulation of Fe in roots and shoots, mir plants triggered the expression of Fe-deficiency-inducible genes, indicating that mir may not be able to utilize Fe for physiological functions. These results clearly suggest that MIR is a rice-specific mitochondrial protein, recently evolved, and plays a significant role in Fe homeostasis.

Original languageEnglish
Pages (from-to)1059-1066
Number of pages8
JournalMolecular Plant
Issue number5
Publication statusPublished - 2009 Sept


  • Fe homeostasis
  • Fe-deficiency-regulated gene
  • Mitochondria
  • Oryza sativa


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