Journal Article

Cloning and functional comparison of a high-affinity K<sup>+</sup> transporter gene <i>PhaHKT1</i> of salt-tolerant and salt-sensitive reed plants

Ryuichi Takahashi, Shenkui Liu and Tetsuo Takano

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 58, issue 15-16, pages 4387-4395
Published in print December 2007 | ISSN: 0022-0957
Published online December 2007 | e-ISSN: 1460-2431 | DOI:

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To understand the mechanisms of ion homeostasis in salt-tolerant and salt-sensitive plants, cDNAs for a high-affinity K+ transporter PhaHKT1 were isolated from salt-sensitive (Utsunomiya) and salt-tolerant (Nanpi, Enchi) reed plants. A cDNA of Utsunomiya (PhaHKT1-u) contained two insertions in the region corresponding to the first and second introns of the PhaHKT1 gene, which resulted in a sequence 141 amino acid residues shorter than that of Nanpi. Expression of PhaHKT1 mRNA was detected in the roots of Nanpi and Enchi plants under K+ starvation conditions and also under Na+ treatment conditions, whereas it was only slightly detected in the roots of Utsunomiya plants under each of these conditions. In the upper parts, PhaHKT1 expression was detected in the Utsunomiya plants, and two signals were obtained in the Nanpi and Enchi plants under all and K+ starvation conditions, respectively. Yeasts expressing the PhaHKT1 of Nanpi (PhaHKT1-n) or the PhaHKT1 of Enchi (PhaHKT1-e) grew better in the presence of NaCl than yeast expressing PhaHKT1-u. Furthermore, yeast expressing a chimeric cDNA containing the 5′ region of the Utsunomiya gene and the 3′ region of the Nanpi gene had partial salt tolerance, and yeast expressing a chimeric cDNA containing the 5′ region of the Nanpi gene and the 3′ region of the Utsunomiya gene had a reduced ability to take up ions. These results suggest that PhaHKT1 plays an important role in the acquisition of K+ and maintenance of ion balance under saline conditions.

Keywords: HKT; PhaHKT1; potassium transporter; reed plants; salt stress; salt tolerance; sodium influx

Journal Article.  4767 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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