title: Systems involved in K+ uptake from diluted solutions in pepper plants as revealed by the use of specific inhibitors.
abstract: Here, the contribution of the HAK1 transporter, the AKT1 channel and a putative AtCHX13 homolog to K(+) uptake in the high-affinity range of concentrations in pepper plants was examined. The limited development of molecular tools in pepper plants precluded a reverse genetics study in this species. By contrast, in the model plant Arabidopsis thaliana, these type of studies have shown that NH(4)(+) and Ba(2+) may be used as specific inhibitors of the two K(+) uptake systems to dissect their contribution in species in which, as in pepper, specific mutant lines are not available. By using these inhibitors together with Na(+) and Cs(+), the relative contributions of CaHAK1, CaAKT1 and a putative AtCHX13 homolog to K(+) acquisition from diluted solutions under different regimens of K(+) supply were studied. The results showed that, in plants completely starved of K(+), the gene encoding CaHAK1 was highly expressed and this system is a major contributor to K(+) uptake. However, K(+) concentrations as low as 50μM reduced CaHAK1 expression and the CaAKT1 channel came into play, participating together with CaHAK1 in K(+) absorption. The contribution of a putative AtCHX13 homolog seemed to be low under this low K(+) supply, but it cannot be ruled out that at higher K(+) concentrations this system participates in K(+) uptake. Studies of this type allow extension of the tools developed in model plants to understand nutrition in important crops.
authors.affiliation: Departamento de Nutrición, Centro de Edafología y Biología Aplicada del Segura-CSIC, Campus de Espinardo, 30100 Murcia, Spain. frubio@cebas.csic.es
authors.forename: Francisco
authors.initials: F
authors.lastname: Rubio
authors.forename: Laura
authors.initials: L
authors.lastname: Arévalo
authors.forename: Fernando
authors.initials: F
authors.lastname: Caballero
authors.forename: María Angeles
authors.initials: MA
authors.lastname: Botella
authors.forename: José Salvador
authors.initials: JS
authors.lastname: Rubio
authors.forename: Francisco
authors.initials: F
authors.lastname: García-Sánchez
authors.forename: Vicente
authors.initials: V
authors.lastname: Martínez
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D002212:Capsicum / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D049990:Membrane Transport Modulators / Q000494:pharmacology*; D009928:Organ Specificity / Q000187:drug effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012996:Solutions
chemical_list: D027682:Cation Transport Proteins; C110543:HAK1 protein, plant; D049990:Membrane Transport Modulators; D010940:Plant Proteins; D012333:RNA, Messenger; D012996:Solutions; D011188:Potassium