High-Affinity K+ Transporters from a Halophyte, Sporobolus virginicus, Mediate Both K+ and Na+ Transport in Transgenic Arabidopsis, X. laevis Oocytes and Yeast

Yuichi Tada, Chisato Endo, Maki Katsuhara, Tomoaki Horie, Mineo Shibasaka, Yoshiki Nakahara, Takamitsu Kurusu

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Class II high-affinity potassium transporters (HKTs) have been proposed to mediate Na+ -K+ co-transport in plants, as well as Na+ and K+ homeostasis under K+ -starved and saline environments. We identified class II HKTs, namely SvHKT2;1 and SvHKT2;2 (SvHKTs), from the halophytic turf grass, Sporobolus virginicus. SvHKT2;2 expression in S. virginicus was up-regulated by NaCl treatment, while SvHKT2;1 expression was assumed to be up-regulated by K+ starvation and down-regulated by NaCl treatment. Localization analysis revealed SvHKTs predominantly targeted the plasma membrane. SvHKTs complemented K+ uptake deficiency in mutant yeast, and showed both inward and outward K+ and Na+ transport activity in Xenopus laevis oocytes. When constitutively expressed in Arabidopsis, SvHKTs mediated K+ and Na+ accumulation in shoots under K+ -starved conditions, and the K+ concentration in xylem saps of transformants was also higher than in those of wild-type plants. These results suggest transporter-enhanced K+ and Na+ uploading to the xylem from xylem parenchyma cells. Together, our data demonstrate that SvHKTs mediate both outward and inward K+ and Na+ transport in X. laevis oocytes, and possibly in plant and yeast cells, depending on the ionic conditions.

Original languageEnglish
Pages (from-to)176-187
Number of pages12
JournalPlant and Cell Physiology
Volume60
Issue number1
DOIs
Publication statusPublished - Jan 1 2019

Keywords

  • Arabidopsis
  • High-affinity potassium transporter
  • K and Na transport
  • K starvation
  • Salt tolerance
  • Sporobolus virginicus

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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