A specific transporter for iron(III)-phytosiderophore in barley roots

Yoshiko Murata, Jian Feng Ma, Naoki Yamaji, Daisei Ueno, Kyosuke Nomoto, Takashi Iwashita

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Abstract

Iron acquisition of graminaceous plants is characterized by the synthesis and secretion of the iron-chelating phytosiderophore, mugineic acid (MA), and by a specific uptake system for iron(III)-phytosiderophore complexes. We identified a gene specifically encoding an iron-phytosiderophore transporter (HvYS1) in barley, which is the most tolerant species to iron deficiency among graminaceous plants. HvYS1 was predicted to encode a polypeptide of 678 amino acids and to have 72.7% identity with ZmYS1, a first protein identified as an iron(III)-phytosiderophore transporter in maize. Real-time RT-PCR analysis showed that the HvYS1 gene was mainly expressed in the roots, and its expression was enhanced under iron deficiency. In situ hybridization analysis of iron-deficient barley roots revealed that the mRNA of HvYS1 was localized in epidermal root cells. Furthermore, immunohistological staining with anti-HvYS1 polyclonal antibody showed the same localization as the mRNA. HvYS1 functionally complemented yeast strains defective in iron uptake on media containing iron(III)-MA, but not iron-nicotianamine (NA). Expression of HvYS1 in Xenopus oocytes showed strict specificity for both metals and ligands: HvYS1 transports only iron(III) chelated with phytosiderophore. The localization and substrate specificity of HvYS1 is different from those of ZmYS1, indicating that HvYS1 is a specific transporter for iron(III)-phytosiderophore involved in primary iron acquisition from soil in barley roots.

Original languageEnglish
Pages (from-to)563-572
Number of pages10
JournalPlant Journal
Volume46
Issue number4
DOIs
Publication statusPublished - May 1 2006

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Keywords

  • Epidermal cells of barley roots
  • Iron(III)-phytosiderophore transporter
  • Mugineic acid
  • Nicotianamine
  • Tolerance of iron deficiency
  • YS1 gene

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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