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

A - Papers appearing in refereed journals

Zhao, F-J., Ago, Y., Mitani, N., Li, R-Y., Su, Y-H., Yamaji, N., McGrath, S. P. and Ma, J. F. 2010. The role of the rice aquaporin Lsi1 in arsenite efflux from roots. New Phytologist. 186 (2), pp. 392-399.

AuthorsZhao, F-J., Ago, Y., Mitani, N., Li, R-Y., Su, Y-H., Yamaji, N., McGrath, S. P. and Ma, J. F.
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 mu 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.

KeywordsPlant Sciences
Year of Publication2010
JournalNew Phytologist
Journal citation186 (2), pp. 392-399
Digital Object Identifier (DOI)doi:10.1111/j.1469-8137.2010.03192.x
PubMed ID20163552
Open accessPublished as non-open access
FunderMinistry of Education, Culture, Sports, Science and Technology of Japan
Ministry of Agriculture, Forestry and Fisheries of Japan
Funder project or codeSEF
ISSN0028646X
PublisherWiley
Grant ID21248009
IPG-0006

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