Na+ Transporter SvHKT1;1 from a Halophytic Turf Grass Is Specifically Upregulated by High Na+ Concentration and Regulates Shoot Na+ Concentration

Kawakami, Yuki; Imran, Shahin; Katsuhara, Maki; Tada, Yuichi

doi:10.3390/ijms21176100

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Na⁺ Transporter SvHKT1;1 from a Halophytic Turf Grass Is Specifically Upregulated by High Na⁺ Concentration and Regulates Shoot Na⁺ Concentration

¹

Graduate School of Bionics, Computer and Media Sciences, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan

²

Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, Okayama 710-0046, Japan

³

School of Biosciences and Biotechnology, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan

^*

Author to whom correspondence should be addressed.

Int. J. Mol. Sci. 2020, 21(17), 6100; https://doi.org/10.3390/ijms21176100

Submission received: 20 July 2020 / Revised: 21 August 2020 / Accepted: 21 August 2020 / Published: 24 August 2020

(This article belongs to the Special Issue Molecular Aspects of Plant Salinity Stress and Tolerance)

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Abstract

We characterized an Na⁺ transporter SvHKT1;1 from a halophytic turf grass, Sporobolus virginicus. SvHKT1;1 mediated inward and outward Na⁺ transport in Xenopus laevis oocytes and did not complement K⁺ transporter-defective mutant yeast. SvHKT1;1 did not complement athkt1;1 mutant Arabidopsis, suggesting its distinguishable function from other typical HKT1 transporters. The transcript was abundant in the shoots compared with the roots in S. virginicus and was upregulated by severe salt stress (500 mM NaCl), but not by lower stress. SvHKT1;1-expressing Arabidopsis lines showed higher shoot Na⁺ concentrations and lower salt tolerance than wild type (WT) plants under nonstress and salt stress conditions and showed higher Na⁺ uptake rate in roots at the early stage of salt treatment. These results suggested that constitutive expression of SvHKT1;1 enhanced Na⁺ uptake in root epidermal cells, followed by increased Na⁺ transport to shoots, which led to reduced salt tolerance. However, Na⁺ concentrations in phloem sap of the SvHKT1;1 lines were higher than those in WT plants under salt stress. Based on this result, together with the induction of the SvHKT1;1 transcription under high salinity stress, it was suggested that SvHKT1;1 plays a role in preventing excess shoot Na⁺ accumulation in S. virginicus.

Keywords: Arabidopsis thaliana; halophyte; high-affinity potassium transporter (HKT); Na⁺ transporter; salt tolerance; Sporobolus virginicus

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MDPI and ACS Style

Kawakami, Y.; Imran, S.; Katsuhara, M.; Tada, Y. Na⁺ Transporter SvHKT1;1 from a Halophytic Turf Grass Is Specifically Upregulated by High Na⁺ Concentration and Regulates Shoot Na⁺ Concentration. Int. J. Mol. Sci. 2020, 21, 6100. https://doi.org/10.3390/ijms21176100

AMA Style

Kawakami Y, Imran S, Katsuhara M, Tada Y. Na⁺ Transporter SvHKT1;1 from a Halophytic Turf Grass Is Specifically Upregulated by High Na⁺ Concentration and Regulates Shoot Na⁺ Concentration. International Journal of Molecular Sciences. 2020; 21(17):6100. https://doi.org/10.3390/ijms21176100

Chicago/Turabian Style

Kawakami, Yuki, Shahin Imran, Maki Katsuhara, and Yuichi Tada. 2020. "Na⁺ Transporter SvHKT1;1 from a Halophytic Turf Grass Is Specifically Upregulated by High Na⁺ Concentration and Regulates Shoot Na⁺ Concentration" International Journal of Molecular Sciences 21, no. 17: 6100. https://doi.org/10.3390/ijms21176100

APA Style

Kawakami, Y., Imran, S., Katsuhara, M., & Tada, Y. (2020). Na⁺ Transporter SvHKT1;1 from a Halophytic Turf Grass Is Specifically Upregulated by High Na⁺ Concentration and Regulates Shoot Na⁺ Concentration. International Journal of Molecular Sciences, 21(17), 6100. https://doi.org/10.3390/ijms21176100

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Na⁺ Transporter SvHKT1;1 from a Halophytic Turf Grass Is Specifically Upregulated by High Na⁺ Concentration and Regulates Shoot Na⁺ Concentration

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