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CHX 14 is a plasma membrane K ‐efflux transporter that regulates K + redistribution in A rabidopsis thaliana
Author(s) -
Zhao Jian,
Li Penghui,
Motes Christy M.,
Park Sunghun,
Hirschi Kendal D.
Publication year - 2015
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12524
Subject(s) - efflux , yeast , mutant , transporter , wild type , xylem , antiporter , biochemistry , biology , plant cell , apoplast , green fluorescent protein , arabidopsis thaliana , microbiology and biotechnology , membrane , chemistry , botany , cell wall , gene
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. CHX 14 expression was induced by elevated K + and histochemical analysis of CHX 14 promoter :: GUS transgenic plants indicated that CHX 14 was expressed in xylem parenchyma of root and shoot vascular tissues of seedlings. CHX 14 knockout ( chx14 ) and CHX 14 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. CHX 14 expression in yeast cells deficient in K + uptake renders the mutant cells more sensitive to deficiencies of K + in the medium. CHX 14 mediates K + efflux in yeast cells loaded with high K + . Uptake experiments using 86 R b + as a tracer for K + with both yeast and plant mutants demonstrated that CHX 14 expression in yeast and in planta mediated low‐affinity K + efflux. Functional green fluorescent protein ( GFP )‐tagged versions of CHX 14 were localized to both the yeast and plant plasma membranes. Taken together, we suggest that CHX 14 is a plasma membrane K + efflux transporter involved in K + homeostasis and K + recirculation.