Plant Physiol. Illumina
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

Plant Physiology Preview
Published on November 4, 2009; 10.1104/pp.109.145722

OPEN ACCESS ARTICLE
This Article
Free via Open Access: OA
Right arrow Full Text (Plant Physiology Preview (PDF))
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Google Scholar
Right arrow Articles by Yao, X.
Right arrow Articles by Schroeder, J. I.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Yao, X.
Right arrow Articles by Schroeder, J. I.
Agricola
Right arrow Articles by Yao, X.
Right arrow Articles by Schroeder, J. I.

Received August 3, 2009
Accepted October 26, 2009

Differential sodium and potassium transport selectivities of the rice OsHKT2;1 and OsHKT2;2 transporters in plant cells

Xuan Yao , Tomoaki Horie , Shaowu Xue , Ho-Yin Leung , Maki Katsuhara , Dennis E. Brodsky , Yan Wu , and Julian I. Schroeder *

Division of Biological Sciences, Cell and Developmental Biology Section, and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093-0116, USA; Key Laboratory of MOE for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China; Group of Molecular and Functional Plant Biology, Research Institute for Bioresources, Okayama University, Kurashiki, Okayama 710-0046, Japan

* Corresponding author; email: julian{at}biomail.ucsd.edu.

Na+ and K+ homeostasis are crucial for plant growth and development. Two HKT transporter/channel classes have been characterized that mediate either Na+ transport or Na+ and K+ transport when expressed in Xenopus oocytes and yeast. However, the Na+/K+ selectivities of the K+ permeable HKT transporters have not yet been studied in plant cells. One study expressing 5' UTR-modified HKT constructs in yeast has questioned the relevance of cation selectivities found in heterologous systems for selectivity predictions in plant cells (Haro et al., 2005). Here we therefore analyze two highly homologous HKT transporters in plant cells, OsHKT2;1 and OsHKT2;2, that show differential K+ permeabilities in heterologous systems. Upon stable expression in cultured Nicotiana tabacum Bright-Yellow 2 (BY2) cells, OsHKT2;1 mediated Na+ uptake, but little Rb+ uptake, consistent with earlier studies and new findings presented here in oocytes. In contrast, OsHKT2;2 mediated Na+-K+ co-transport in plant cells such that extracellular K+ stimulates OsHKT2;2-mediated Na+ influx and vice versa. Furthermore, at millimolar Na+ concentrations OsHKT2;2 mediated Na+ influx into plant cells without adding extracellular K+. In addition, the presence of external K+ and Ca2+ down-regulated OsHKT2;1-mediated Na+ influx in two plant systems, BY2 cells and intact rice roots, and also in Xenopus oocytes. The present study shows that the Na+/K+ selectivities of these HKT transporters in plant cells coincide closely with the selectivities in oocytes and yeast and furthermore that OsHKT transporter selectivities in plant cells depend on the imposed cationic conditions, supporting the model that HKT transporters are multi-ion pores.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
ASPB Publications PLANT PHYSIOLOGY® THE PLANT CELL
Copyright © 2009 by the American Society of Plant Biologists