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

Plant J. 2006 May;46(4):563-72. doi: 10.1111/j.1365-313X.2006.02714.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Ferric Compounds / metabolism*
  • Hordeum / cytology
  • Hordeum / metabolism*
  • Iron-Binding Proteins / metabolism*
  • Membrane Transport Proteins / analysis
  • Membrane Transport Proteins / chemistry
  • Membrane Transport Proteins / physiology*
  • Molecular Sequence Data
  • Phylogeny
  • Plant Proteins / analysis
  • Plant Proteins / chemistry
  • Plant Proteins / physiology*
  • Plant Roots / metabolism
  • Protein Structure, Tertiary
  • RNA, Messenger / metabolism
  • Sequence Alignment
  • Xenopus


  • Ferric Compounds
  • Iron-Binding Proteins
  • Membrane Transport Proteins
  • Plant Proteins
  • RNA, Messenger