Studies on Arabidopsis athak5, atakt1 double mutants disclose the range of concentrations at which AtHAK5, AtAKT1 and unknown systems mediate K uptake.
The high-affinity K(+) transporter AtHAK5 and the inward-rectifier K(+) channel AtAKT1 have been described to contribute to K(+) uptake in Arabidopsis thaliana. Studies with T-DNA insertion lines showed that both systems participate in the high-affinity range of concentrations and only AtAKT1 in the low-affinity range. However the contribution of other systems could not be excluded with the information and plant material available. The results presented here with a double knock-out athak5, atakt1 mutant show that AtHAK5 is the only system mediating K(+) uptake at concentrations below 0.01 mM. In the range between 0.01 and 0.05 mM K(+) AtHAK5 and AtAKT1 are the only contributors to K(+) acquisition. At higher K(+) concentrations, unknown systems come into operation and participate together with AtAKT1 in low-affinity K(+) uptake. These systems can supply sufficient K(+) to promote plant growth even in the absence of AtAKT1 or in the presence of 10 mM K(+) where AtAKT1 is not essential.
Rubio
Francisco
F
Departamento de Nutrición Vegetal, Centro de Edafología y Biología Aplicada del Segura-CSIC, Campus de Espinardo, Murcia 30100, Spain. frubio@cebas.csic.es
Alemán
Fernando
F
Nieves-Cordones
Manuel
M
Martínez
Vicente
V
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D004269:DNA, Bacterial; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D016254:Mutagenesis, Insertional; D009154:Mutation; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D027961:Potassium-Hydrogen Antiporters; D027981:Symporters / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D015221:Potassium Channels; D027961:Potassium-Hydrogen Antiporters; D027981:Symporters; C036483:T-DNA; C501258:potassium transporter, Arabidopsis; C074500:AKT1 protein, Arabidopsis; D011188:Potassium