High-affinity K+ transporter PhaHAK5 is expressed only in salt-sensitive reed plants and shows Na+ permeability under NaCl stress
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- Takahashi, R., Nishio, T., Ichizen, N. et al. Plant Cell Rep (2007) 26: 1673. doi:10.1007/s00299-007-0364-1
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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.