High-affinity K+ transporter PhaHAK5 is expressed only in salt-sensitive reed plants and shows Na+ permeability under NaCl stress.
To understand the mechanism of ion homeostasis in salt tolerant and sensitive plants, we isolated cDNAs for K(+) transporter PhaHAK1-u and PhaHAK5-u from reed plants. PhaHAK1-u belongs to group I and PhaHAK5-u belongs to group IV by phylogenetic analysis, respectively. PhaHAK5-u is predicted to be a plasma membrane transporter, and shows high-affinity K(+) transporter. Expression of PhaHAK5 was found in salt-sensitive reed plants, but not in any parts of salt-tolerant reed plants maintained under both control and K(+) starvation conditions. Under the NaCl stress, the K(+) uptake ability of the yeast strain expressing PhaHAK5-u was remarkably lower than that of the yeast strain expressing PhaHAK1-u, and PhaHAK5-u showed Na(+) permeability. These results suggest that PhaHAK5 is one of the routes by which Na(+) enters cells.
Takahashi
Ryuichi
R
Asian Natural Environmental Science Center, The University of Tokyo, Nishitokyo-shi, Tokyo 188-0002, Japan.
Nishio
Takayoshi
T
Ichizen
Nobumasa
N
Takano
Tetsuo
T
D000222:Adaptation, Physiological; D015139:Blotting, Southern; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008969:Molecular Sequence Data; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D006109:Poaceae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*; D013997:Time Factors; D014170:Transformation, Genetic / Q000187:drug effects
D027682:Cation Transport Proteins; D018076:DNA, Complementary; D010940:Plant Proteins; D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium