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The role of the rice aquaporin Lsi1 in arsenite efflux from roots
Author(s) -
Zhao FangJie,
Ago Yukiko,
Mitani Namiki,
Li RenYing,
Su YuHong,
Yamaji Naoki,
McGrath Steve P.,
Ma Jian Feng
Publication year - 2010
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2010.03192.x
Subject(s) - arsenite , efflux , arsenate , aquaporin , arsenic , chemistry , biochemistry , oryza sativa , mutant , biology , gene , organic chemistry
Summary• 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 μ m 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.