A putative role for the plasma membrane potential in the control of the expression of the gene encoding the tomato high-affinity potassium transporter HAK5
A chimeric CaHAK1–LeHAK5 transporter with only 15 amino acids of CaHAK1 in the N-terminus mediates high-affinity K+ uptake in yeast cells. Kinetic and expression analyses strongly suggest that LeHAK5 mediates a significant proportion of the high-affinity K+ uptake shown by K+-starved tomato (Solanum...
| Autores: | , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2008 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/344643 |
| Acceso en línea: | http://hdl.handle.net/10261/344643 |
| Access Level: | acceso abierto |
| Palabra clave: | Ammonium Gene expression Plasma membrane potential Potassium Transport |
| Sumario: | A chimeric CaHAK1–LeHAK5 transporter with only 15 amino acids of CaHAK1 in the N-terminus mediates high-affinity K+ uptake in yeast cells. Kinetic and expression analyses strongly suggest that LeHAK5 mediates a significant proportion of the high-affinity K+ uptake shown by K+-starved tomato (Solanum lycopersicum) plants. The development of high-affinity K+ uptake, putatively mediated by LeHAK5, was correlated with increased LeHAK5 mRNA levels and a more negative electrical potential difference across the plasma membrane of root epidermal and cortical cells. However, this increase in high-affinity K+ uptake was not correlated with the root K+ content. Thus, (i) growth conditions that result in a hyperpolarized root plasma membrane potential, such as K+ starvation or growth in the presence of NH4 +, but which do not decrease the K+ content, lead to increased LeHAK5 expression; (ii) the presence of NaCl in the growth solution, which prevents the hyperpolarization induced by K+ starvation, also prevents LeHAK5 expression. Moreover, once the gene is induced, depolarization of the plasma membrane potential then produces a decrease in the LeHAK5 mRNA. On the basis of these results, we propose that the plant membrane electrical potential plays a role in the regulation of the expression of this gene encoding a high-affinity K+ transporter |
|---|