A rice phenolic efflux transporter is essential for solubilizing precipitated apoplasmic iron in the plant stele

Yasuhiro Ishimaru, Yusuke Kakei, Hugo Shimo, Khurram Bashir, Yutaka Sato, Yuki Sato, Nobuyuki Uozumi, Hiromi Nakanishi, Naoko K. Nishizawa

Research output: Contribution to journalArticlepeer-review

123 Citations (Scopus)


Iron deficiency is one of the major agricultural problems, as 30% of the arable land of the world is too alkaline for optimal crop production, rendering plants short of available iron despite its abundance. To take up apoplasmic precipitated iron, plants secrete phenolics such as protocatechuic acid (PCA) and caffeic acid. The molecular pathways and genes of iron uptake strategies are already characterized, whereas the molecular mechanisms of phenolics synthesis and secretion have not been clarified, and no phenolics efflux transporters have been identified in plants yet. Here we describe the identification of a phenolics efflux transporter in rice. We identified a cadmium-accumulating rice mutant in which the amount of PCA and caffeic acid in the xylem sap was dramatically reduced and hence named it phenolics efflux zero 1 (pez1). PEZ1 localized to the plasma membrane and transported PCA when expressed in Xenopus laevis oocytes. PEZ1 localized mainly in the stele of roots. In the roots of pez1, precipitated apoplasmic iron increased. The growth of PEZ1 overexpression lines was severely restricted, and these lines accumulated more iron as a result of the high solubilization of precipitated apoplasmic iron in the stele. We show that PEZ1 is responsible for an increase of PCA concentration in the xylem sap and is essential for the utilization of apoplasmic precipitated iron in the stele.

Original languageEnglish
Pages (from-to)24649-24655
Number of pages7
JournalJournal of Biological Chemistry
Issue number28
Publication statusPublished - 2011 Jul 15

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'A rice phenolic efflux transporter is essential for solubilizing precipitated apoplasmic iron in the plant stele'. Together they form a unique fingerprint.

Cite this