Characterization of two HKT1;4 Transporters from triticum monococcum to elucidate the determinants of the wheat salt tolerance Nax1 QTL

Sana Tounsi, Siwar Ben Amar, Khaled Masmoudi, Hervé Sentenac, Faiçal Brini, Anne Aliénor Véry

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33 Citations (Scopus)


TmHKT1;4-A1 and TmHKT1;4-A2 are two Na+ transporter genes that have been identified as associated with the salt tolerance Nax1 locus found in a durum wheat (Triticum turgidum L. subsp. durum) line issued from a cross with T. monococcum. In the present study, we were interested in getting clues on the molecular mechanisms underpinning this salt tolerance quantitative trait locus (QTL). By analyzing the phylogenetic relationships between wheat and T. monococcum HKT1;4-Type genes, we found that durum and bread wheat genomes possess a close homolog of TmHKT1;4-A1, but no functional close homolog of TmHKT1;4-A2. Furthermore, performing real-Time reverse transcription-PCR experiments, we showed that TmHKT1;4-A1 and TmHKT1;4-A2 are similarly expressed in the leaves but that TmHKT1;4-A2 is more strongly expressed in the roots, which would enable it to contribute more to the prevention of Na+ transfer to the shoots upon salt stress. We also functionally characterized the TmHKT1;4-A1 and TmHKT1;4-A2 transporters by expressing them in Xenopus oocytes. The two transporters displayed close functional properties (high Na+/K+ selectivity, low affinity for Na+, stimulation by external K+ of Na+ transport), but differed in some quantitative parameters: Na+ affinity was 3-fold lower and the maximal inward conductance was 3-fold higher in TmHKT1;4-A2 than in TmHKT1;4-A1. The conductance of TmHKT1;4-A2 at high Na+ concentration (>10 mM) was also shown to be higher than that of the two durum wheat HKT1;4-Type transporters so far characterized. Altogether, these data support the hypothesis that TmHKT1;4-A2 is responsible for the Nax1 trait and provide new insight into the understanding of this QTL.

Original languageEnglish
Pages (from-to)2047-2057
Number of pages11
JournalPlant and Cell Physiology
Issue number10
Publication statusPublished - Oct 2016


  • HKT1
  • Nax1 salt tolerance QTL
  • Sodium transport
  • Triticum monococcum
  • Xenopus oocyte

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology


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