Phytosiderophore efflux transporters are crucial for iron acquisition in graminaceous plants

Tomoko Nozoye, Seiji Nagasaka, Takanori Kobayashi, Michiko Takahashi, Yuki Sato, Yoko Sato, Nobuyuki Uozumi, Hiromi Nakanishi, Naoko K. Nishizawa

Research output: Contribution to journalArticlepeer-review

244 Citations (Scopus)

Abstract

Eukaryotic organisms have developed diverse mechanisms for the acquisition of iron, which is required for their survival. Graminaceous plants use a chelation strategy. They secrete phytosiderophore compounds, which solubilize iron in the soil, and then take up the resulting iron-phytosiderophore complexes. Bacteria and mammals also secrete siderophores to acquire iron. Although phytosiderophore secretion is crucial for plant growth, its molecular mechanism remains unknown. Here, we show that the efflux of deoxymugineic acid, the primary phytosiderophore from rice and barley, involves the TOM1 and HvTOM1 genes, respectively. Xenopus laevis oocytes expressing TOM1 or HvTOM1 released 14C-labeled deoxymugineic acid but not 14C-labeled nicotianamine, a structural analog and biosynthetic precursor of deoxymugineic acid, indicating that the TOM1 and HvTOM1 proteins are the phytosiderophore efflux transporters. Under conditions of iron deficiency, rice and barley roots express high levels of TOM1 and HvTOM1, respectively, and the overexpression of these genes increased tolerance to iron deficiency. In rice roots, the efficiency of deoxymugineic acid secretion was enhanced by overexpression of TOM1 and decreased by its repression, providing further evidence that TOM1 encodes the efflux transporter of deoxymugineic acid. We have also identified two genes encoding efflux transporters of nicotianamine, ENA1 and ENA2. Our identification of phytosiderophore efflux transporters has revealed the final piece in the molecular machinery of iron acquisition in graminaceous plants.

Original languageEnglish
Pages (from-to)5446-5454
Number of pages9
JournalJournal of Biological Chemistry
Volume286
Issue number7
DOIs
Publication statusPublished - 2011 Feb 18

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Phytosiderophore efflux transporters are crucial for iron acquisition in graminaceous plants'. Together they form a unique fingerprint.

Cite this