The role of the rice aquaporin Lsi1 in arsenite efflux from roots

Fang Jie Zhao, Yukiko Ago, Namiki Mitani, Ren Ying Li, Yu Hong Su, Naoki Yamaji, Steve P. McGrath, Jian Feng Ma

Research output: Contribution to journalArticle

113 Citations (Scopus)

Abstract

When supplied with arsenate (As(V)), plant roots extrude a substantial amount of arsenite (As(III)) to the external medium through as yet unidentified pathways. The rice (Oryza sativa) silicon transporter Lsi1 (OsNIP2;1, an aquaporin channel) is the major entry route of arsenite into rice roots. Whether Lsi1 also mediates arsenite efflux was investigated. Expression of Lsi1 in Xenopus laevis oocytes enhanced arsenite efflux, indicating that Lsi1 facilitates arsenite transport bidirectionally. Arsenite was the predominant arsenic species in arsenate-exposed rice plants. During 24-h exposure to 5 lM arsenate, rice roots extruded arsenite to the external medium rapidly, accounting for 60-90% of the arsenate uptake. A rice mutant defective in Lsi1 (lsi1) extruded significantly less arsenite than the wild-type rice and, as a result, accumulated more arsenite in the roots. By contrast, Lsi2 mutation had little effect on arsenite efflux to the external medium. We conclude that Lsi1 plays a role in arsenite efflux in rice roots exposed to arsenate. However, this pathway accounts for only 15-20% of the total efflux, suggesting the existence of other efflux transporters.

Original languageEnglish
Pages (from-to)392-399
Number of pages8
JournalNew Phytologist
Volume186
Issue number2
DOIs
Publication statusPublished - Apr 1 2010

Keywords

  • Aquaporin
  • Arsenic accumulation
  • Arsenite (As(III)) efflux
  • Rice
  • Silicon transporter

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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