title: High-affinity K+ uptake in pepper plants.
abstract: High-affinity K+ uptake is an essential process for plant nutrition under K+-limiting conditions. The results presented here demonstrate that pepper (Capsicum annuum) plants grown in the absence of NH4+ and starved of K+ show an NH4+-sensitive high-affinity K+ uptake that allows plant roots to deplete external K+ to values below 1 microM. When plants are grown in the presence of NH4+, high-affinity K+ uptake is not inhibited by NH4+. Although NH4+-grown plants deplete external K+ below 1 microM in the absence of NH4+, when 1 mM NH4+ is present they do not deplete external K+ below 10 microM. A K+ transporter of the HAK family, CaHAK1, is very likely mediating the NH4+-sensitive component of the high-affinity K+ uptake in pepper roots. CaHAK1 is strongly induced in the roots that show the NH4+-sensitive high-affinity K+ uptake and its induction is reduced in K+-starved plants grown in the presence of NH4+. The NH4+-insensitive K+ uptake may be mediated by an AKT1-like K+ channel.
authors.affiliation: Departamento de Nutrición Vegetal, Centro de Edafología y Biología Aplicada del Segura-CSIC, Apartado de Correos 164, E-30100 Murcia, Spain.
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Martínez-Cordero
authors.forename: Vicente
authors.initials: V
authors.lastname: Martínez
authors.forename: Francisco
authors.initials: F
authors.lastname: Rubio
mesh_terms: D001693:Biological Transport, Active; D002212:Capsicum / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000378:metabolism; D002586:Cesium / Q000494:pharmacology; D004790:Enzyme Induction; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D013997:Time Factors
chemical_list: D027682:Cation Transport Proteins; C110543:HAK1 protein, plant; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds; D002586:Cesium; D012964:Sodium; D011188:Potassium