Characterization of rice KT/HAK/KUP potassium transporters and K<sup>+</sup> uptake by HAK1 from <i>Oryza sativa</i>

  • Okada Tomoyuki
    Faculty of Agriculture, Kochi University Graduate School of Biological Sciences, Nara Institute of Science and Technology Kochi Agricultural Research Center
  • Yamane Sousuke
    Faculty of Agriculture, Kochi University
  • Yamaguchi Masatoshi
    Graduate School of Biological Engineering, Saitama University
  • Kato Ko
    Graduate School of Biological Sciences, Nara Institute of Science and Technology
  • Shinmyo Atsuhiko
    Graduate School of Biological Sciences, Nara Institute of Science and Technology
  • Tsunemitsu Yuta
    Faculty of Agriculture, Kochi University
  • Iwasaki Kozo
    Faculty of Agriculture, Kochi University
  • Ueno Daisei
    Faculty of Agriculture, Kochi University
  • Demura Taku
    Graduate School of Biological Sciences, Nara Institute of Science and Technology

Bibliographic Information

Other Title
  • Characterization of rice KT/HAK/KUP potassium transporters and K⁺ uptake by HAK1 from Oryza sativa

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Abstract

<p>Plant high-affinity K+ (HAK) transporters are divided into four major clusters. Cluster I transporters, in particular, are thought to have high-affinity for K+. Of the 27 HAK genes in rice, eight HAK transporters belong to cluster I. In this study, we investigated the temporal expression patterns during K+ deficiency and K+ transport activity of these eight HAK transporters. The expression of seven HAK genes except OsHAK20 was detected. Expression of OsHAK1, OsHAK5 and OsHAK21 was induced in response to K+ deficiency; however, that of other genes was not. Six of the eight HAK transporters—OsHAK1, OsHAK5, OsHAK19, OsHAK20, OsHAK21, and OsHAK27—complemented the K+-transporter-deficient yeast or bacterial strain. Further, the yeast cells expressing OsHAK1 were more sensitive to Na+ than those expressing OsHAK5. Mutant analysis showed that the high-affinity K+ uptake activity was almost undetectable in oshak1 mutants in a low-K+ medium (0.02 mM). In addition, the high-affinity K+ uptake activity of wild-type plants was inhibited by mild salt stress (20 mM NaCl); however, Na+ permeability of OsHAK1 was not detected in Escherichia coli cells. The high-affinity K+ uptake activity by leaf blades was detected in wild-type plants, while it was not detected in oshak1 mutants. Our results suggest that OsHAK1 and OsHAK5 are the two important components of cluster I corresponding to low-K+ conditions, and that the transport activity of OsHAK1, unlike that of OsHAK5, is sensitive to Na+. Further, OsHAK1 is suggested to involve in foliar K+ uptake.</p>

Journal

  • Plant Biotechnology

    Plant Biotechnology 35 (2), 101-111, 2018-06-25

    Japanese Society for Plant Biotechnology

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