Location: Children's Nutrition Research CenterTitle: CHX14 is a plasma membrane K-efflux transporter that regulates K+ redistribution in "Arabidopsis thaliana"
|Zhao, Jian - Huazhong Agricultural University|
|Li, Penghui - Huazhong Agricultural University|
|Motes, Christy - Samuel Roberts Noble Foundation, Inc|
|Park, Sunghun - Kansas State University|
|Hirschi, Kendal - Children'S Nutrition Research Center (CNRC)|
Submitted to: Plant, Cell & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2015
Publication Date: 11/1/2015
Publication URL: http://handle.nal.usda.gov/10113/62110
Citation: Zhao, J., Li, P., Motes, C.M., Park, S., Hirschi, K.D. 2015. CHX14 is a plasma membrane K-efflux transporter that regulates K+ redistribution in "Arabidopsis thaliana". Plant, Cell & Environment. 38(11):2223-2238.
Interpretive Summary: Potassium is a vital nutrient for both plants and animals. Potassium stimulates growth, helps in the utilization of water and makes plants more resistant to various stresses. The ability to efficiently move potassium is thus essential for improved crop productivity. However, the process of potassium movement in plants is poorly understood. Here we have identified and characterize a transporter in plants that helps shuttle potassium to various tissues. We used genetic and biochemical approaches to show that the transporter circulates potassium out of cells and helps boost potassium to nearby cells that are deficient in this nutrient. Engineering and controlling this transporter will be important as future work seeks to boost potassium levels in crops to improve yield, nutrient density and reduce water usage.
Technical Abstract: 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.