LjMATE1: A citrate transporter responsible for iron supply to the nodule infection zone of lotus japonicus

Kojiro Takanashi, Kengo Yokosho, Kazuhiko Saeki, Akifumi Sugiyama, Shusei Sato, Satoshi Tabata, Jian Feng Ma, Kazufumi Yazaki

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Symbiotic nitrogen fixation by intracellular rhizobia within legume root nodules requires the exchange of nutrients between host plant cells and their resident bacteria. While exchanged molecules imply nitrogen compounds, carbohydrates and also various minerals, knowledge of the molecular basis of plant transporters that mediate those metabolite exchanges is still limited. In this study, we have shown that a multidrug and toxic compound extrusion (MATE) protein, LjMATE1, is specifically induced during nodule formation, which nearly paralleled nodule maturation, in a model legume Lotus japonicus. Reporter gene experiments indicated that the expression of LjMATE1 was restricted to the infection zone of nodules. To characterize the transport function of LjMATE1, we conducted a biochemical analysis using a heterologous expression system, Xenopus oocytes, and found that LjMATE1 is a specific transporter for citrate. The physiological role of LjMATE1 was analyzed after generation of L. japonicus RNA interference (RNAi) lines. One RNAi knock-down line revealed limited growth under nitrogen-deficient conditions with inoculation of rhizobia compared with the controls (the wild type and an RNAi line in which LjMATE1 was not suppressed). It was noteworthy that Fe localization was clearly altered in nodule tissues of the knock-down line. These results strongly suggest that LjMATE1 is a nodule-specific transporter that assists the translocation of Fe from the root to nodules by providing citrate.

Original languageEnglish
Pages (from-to)585-594
Number of pages10
JournalPlant and Cell Physiology
Volume54
Issue number4
DOIs
Publication statusPublished - Apr 2013

Keywords

  • Citrate
  • Fe translocation
  • Lotus japonicus
  • MATE
  • Nodulation

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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