CHX14 is a plasma membrane K-efflux transporter that regulates K(+) redistribution in Arabidopsis thaliana

Plant Cell Environ. 2015 Nov;38(11):2223-38. doi: 10.1111/pce.12524. Epub 2015 Apr 25.


Potassium (K(+) ) is essential for plant growth and development, yet the molecular identity of many K(+) transporters remains elusive. Here we characterized cation/H(+) exchanger (CHX) 14 as a plasma membrane K(+) transporter. CHX14 expression was induced by elevated K(+) and histochemical analysis of CHX14 promoter::GUS transgenic plants indicated that CHX14 was expressed in xylem parenchyma of root and shoot vascular tissues of seedlings. CHX14 knockout (chx14) and CHX14 overexpression seedlings displayed different growth phenotypes during K(+) stress as compared with wild-type seedlings. Roots of mutant seedlings displayed higher K(+) uptake rates than wild-type roots. CHX14 expression in yeast cells deficient in K(+) uptake renders the mutant cells more sensitive to deficiencies of K(+) in the medium. CHX14 mediates K(+) efflux in yeast cells loaded with high K(+) . Uptake experiments using (86) Rb(+) as a tracer for K(+) with both yeast and plant mutants demonstrated that CHX14 expression in yeast and in planta mediated low-affinity K(+) efflux. Functional green fluorescent protein (GFP)-tagged versions of CHX14 were localized to both the yeast and plant plasma membranes. Taken together, we suggest that CHX14 is a plasma membrane K(+) efflux transporter involved in K(+) homeostasis and K(+) recirculation.

Keywords: Arabidopsis; CHX; nutrition; potassium.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / analysis
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / physiology*
  • Cell Membrane / metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant
  • Homeostasis
  • Plant Roots / genetics
  • Plant Roots / metabolism
  • Plant Shoots / genetics
  • Plant Shoots / metabolism
  • Potassium / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Seedlings / genetics
  • Seedlings / metabolism
  • Sodium-Hydrogen Exchangers / analysis
  • Sodium-Hydrogen Exchangers / genetics
  • Sodium-Hydrogen Exchangers / physiology*


  • Arabidopsis Proteins
  • CHX17 protein, Arabidopsis
  • Sodium-Hydrogen Exchangers
  • Potassium

Associated data

  • GENBANK/EF571900