Abstract
The high-affinity potassium transporters (HKT) are highly important for stress tolerance in plants as they uniquely maintain K+/Na+ ratio for their survival and growth. In this study a novel HKT gene AlHKT2;1 was isolated and characterized from salt secreting halophyte, Aeluropus lagopoides. The AlHKT2;1 cDNA comprised of an open reading frame of 1,581 bp, encoding a protein of 526 amino acid residues. It belongs to class II HKTs and showed high homology with other HKT genes. Functional characterization of AlHKT2;1 in both K+ uptake‐deficient (WΔ6) and Na+-sensitive yeast mutants (G19) showed the characteristic feature of low-affinity K+ transporter supporting the growth at >1 mM KCl concentration. The transformed yeast cells showed high sensitivity to NaCl; however, the addition of KCl along with NaCl support the growth of AlHKT2;1 expressing mutant. Ion content analysis of yeast cells with AlHKT2;1 grown in high NaCl medium supplemented with KCl revealed that salt tolerance was correlated with accumulation of K+ during salt stress. These results suggest that AlHKT2;1 plays an important role in the K+ uptake during salt stress and in maintaining a high K+/Na+ ratio in the cytosol.
Similar content being viewed by others
References
Adams, E., & Shin, R. (2014). Transport, signaling, and homeostasis of potassium and sodium in plants. Journal of Integrative Plant Biology, 56, 231–249.
Maser, P., Thomine, S., Schroeder, J. I., Ward, J. M., Hirschi, K., Sze, H., et al. (2001). Phylogenetic relationships within cation transporter families of Arabidopsis. Plant Physiology, 126, 1646–1667.
Maser, P., Gierth, M., & Schroeder, J. I. (2002). Molecular mechanisms of potassium and sodium uptake in plants. Plant and Soil, 247, 43–54.
Almeida, P., Katschnig, D., & de Boer, A. H. (2013). HKT transporters-state of the art. International Journal of Molecular Sciences, 14, 20359–20385.
Platten, J. D., Cotsaftis, O., Berthomieu, P., Bohnert, H., Davenport, R. J., Fairbairn, D. J., et al. (2006). Nomenclature for HKT transporters, key determinants of plant salinity tolerance. Trends in Plant Science, 11, 372–374.
Maser, P., Hosoo, Y., Goshima, S., Horie, T., Eckelman, B., Yamada, K., et al. (2002). Glycine residues in potassium channel-like selectivity filters determine potassium selectivity in four-loop-per-subunit HKT transporters from plants. Proceedings of the National Academy of Sciences of the United States of America, 99, 6428–6433.
Ali, Z., Park, H. C., Ali, A., Oh, D. H., Aman, R., Kropornicka, A., et al. (2012). TsHKT1;2, a HKT1 homolog from the extremophile Arabidopsis relative Thellungiella salsuginea, shows K+ specificity in the presence of NaCl. Plant Physiology, 158, 1463–1474.
Takahashi, R., Liu, S., & Takano, T. (2007). Cloning and functional comparison of a high-affinity K+ transporter gene PhaHKT1 of salt-tolerant and salt-sensitive reed plants. Journal of Experimental Botany, 58, 4387–4395.
Ardie, S. W., Xie, L., Takahashi, R., Liu, S., & Takano, T. (2009). Cloning of a high-affinity K+ transporter gene PutHKT2;1 from Puccinellia tenuiflora and its functional comparison with OsHKT2;1 from rice in yeast and Arabidopsis. Journal of Experimental Botany, 60, 3491–3502.
Gulzar, S., & Khan, M. A. (2001). Seed germination of a halophytic grass Aeluropus lagopoides. Annals of Botany, 87, 319–324.
Mohsenzadeh, S., Malboobi, M. A., Razavi, K., & Farrahi-Aschtiani, S. (2006). Physiological and molecular responses of Aeluropus lagopoides (Poaceae) to water deficit. Environmental and Experimental Botany, 56, 314–322.
Sobhanian, H., Motamed, N., Jazii, F. R., Nakamura, T., & Komatsu, S. (2010). Salt stress induced differential proteome and metabolome response in the shoots of Aeluropus lagopoides (Poaceae), a Halophyte C-4 Plant. Journal of Proteome Research, 9, 2882–2897.
Hoagland, D. R., & Arnon, D. I. (1950). The water-culture method for growing plants without soil. Circular. California Agricultural Experiment Station, 347, 1–32.
Altschul, S. F., Gish, W., Miller, W., Myers, E. W., & Lipman, D. J. (1990). Basic local alignment search tool. Journal of Molecular Biology, 215, 403–410.
Tamura, K., Peterson, D., Peterson, N., Stecher, G., Nei, M., & Kumar, S. (2011). MEGA5: molecular evolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. Molecular Biology and Evolution, 28, 2731–2739.
Omasits, U., Ahrens, C. H., Muller, S., & Wollscheid, B. (2014). Protter: interactive protein feature visualization and integration with experimental proteomic data. Bioinformatics, 30, 884–886.
Haro, R., & Rodriguez-Navarro, A. (2003). Functional analysis of the M2(D) helix of the TRK1 potassium transporter of Saccharomyces cerevisiae. Biochimica et Biophysica Acta, 1613, 1–6.
Quintero, F. J., Garciadeblas, B., & Rodriguez-Navarro, A. (1996). The SAL1 gene of Arabidopsis, encoding an enzyme with 3′(2′),5′-bisphosphate nucleotidase and inositol polyphosphate 1-phosphatase activities, increases salt tolerance in yeast. Plant Cell, 8, 529–537.
Brunelli, J. P., & Pall, M. L. (1993). A series of yeast/Escherichia coli λ expression vectors designed for directional cloning of cDNAs and cre/lox-mediated plasmid excision. Yeast, 9, 1309–1318.
Gietz, D., Stjean, A., Woods, R. A., & Schiestl, R. H. (1992). Improved method for high efficiency transformation of intact yeast cells. Nucleic Acids Research, 20, 1425.
Rodriguez-Navarro, A., & Ramos, J. (1984). Dual system for potassium transport in Saccharomyces cerevisiae. Journal of Bacteriology, 159, 940–945.
Durell, S. R., & Guy, H. R. (1999). Structural models of the KtrB, TrkH, and Trk1,2 symporters based on the structure of the KcsA K+ channel. Biophysical Journal, 77, 789–807.
Durell, S. R., Hao, Y. L., Nakamura, T., Bakker, E. P., & Guy, H. R. (1999). Evolutionary relationship between K+ channels and symporters. Biophysical Journal, 77, 775–788.
Kato, Y., Sakaguchi, M., Mori, Y., Saito, K., Nakamura, T., Bakker, E. P., et al. (2001). Evidence in support of a four transmembrane-pore-transmembrane topology model for the Arabidopsis thaliana Na+/K+ translocating AtHKT1 protein, a member of the superfamily of K+ transporters. Proceedings of the National Academy of Sciences of the United States of America, 98, 6488–6493.
Kato, N., Akai, M., Zulkifli, L., Matsuda, N., Kato, Y., Goshima, S., et al. (2007). Role of positively charged amino acids in the M2(D) transmembrane helix of Ktr/Trk/HKT type cation transporters. Channels, 1, 161–171.
Gassmann, W., Rubio, F., & Schroeder, J. I. (1996). Alkali cation selectivity of the wheat root high-affinity potassium transporter HKT1. Plant Journal, 10, 869–882.
Corratge-Faillie, C., Jabnoune, M., Zimmermann, S., Very, A. A., Fizames, C., & Sentenac, H. (2010). Potassium and sodium transport in non-animal cells: the Trk/Ktr/HKT transporter family. Cellular and Molecular Life Sciences, 67, 2511–2532.
Rubio, F., Gassmann, W., & Schroeder, J. I. (1995). Sodium-driven potassium uptake by the plant potassium transporter HKT1 and mutations conferring salt tolerance. Science, 270, 1660–1663.
Uozumi, N., Kim, E. J., Rubio, F., Yamaguchi, T., Muto, S., Tsuboi, A., et al. (2000). The Arabidopsis HKT1 gene homolog mediates inward Na+ currents in Xenopus laevis oocytes and Na+ uptake in Saccharomyces cerevisiae. Plant Physiology, 122, 1249–1259.
Sassi, A., Mieulet, D., Khan, I., Moreau, B., Gaillard, I., Sentenac, H., & Very, A. A. (2012). The rice monovalent cation transporter OsHKT2;4: revisited ionic selectivity. Plant Physiology, 160, 498–510.
Schachtman, D. P., & Schroeder, J. I. (1994). Structure and transport mechanism of a high-affinity potassium uptake transporter from higher plants. Nature, 370, 655–658.
Horie, T., Sugawara, M., Okunou, K., Nakayama, H., Schroeder, J. I., Shinmyo, A., & Yoshida, K. (2008). Functions of HKT transporters in sodium transport in roots and in protecting leaves from salinity stress. Plant Biotechnology, 25, 233–239.
Rubio, F., Schwarz, M., Gassmann, W., & Schroeder, J. I. (1999). Genetic selection of mutations in the high affinity K+ transporter HKT1 that define functions of a loop site for reduced Na+ permeability and increased Na+ tolerance. Journal of Biological Chemistry, 274, 6839–6847.
Horie, T., Yoshida, K., Nakayama, H., Yamada, K., Oiki, S., & Shinmyo, A. (2001). Two types of HKT transporters with different properties of Na+ and K+ transport in Oryza sativa. Plant Journal, 27, 129–138.
Corratge, C., Zimmermann, S., Lambilliotte, R. R. L., Plassard, C., Marmeisse, R., Thibaud, J. B., et al. (2007). Molecular and functional characterization of a Na+–K+ transporter from the Trk family in the ectomycorrhizal fungus Hebeloma cylindrosporum. Journal of Biological Chemistry, 282, 26057–26066.
Garciadeblas, B., Senn, M. E., Banuelos, M. A., & Rodriguez-Navarro, A. (2003). Sodium transport and HKT transporters: the rice model. Plant Journal, 34, 788–801.
Golldack, D., Su, H., Quigley, F., Kamasani, U. R., Munoz-Garay, C., Balderas, E., et al. (2002). Characterization of a HKT-type transporter in rice as a general alkali cation transporter. Plant Journal, 31, 529–542.
Acknowledgments
CSIR-CSMCRI Communication No. 185 as provided by BDIM. We are grateful to Dr Alonso Rodriguez-Navarro, Universidad Politecnica de Madrid, Spain, for kindly providing us with the WΔ6, W303.1A and G19 yeast strains and for the helpful discussions. The financial assistance from CSIR (OLP 0067) is greatly acknowledged. PA is thankful for Sennior Research Associateship (CSIR Scientists’ Pool Scheme). PS and JK are thankful to CSIR for Senior Research Fellowship and Junior Research Fellowship, respectively and AcSIR for enrolment in Ph.D.
Author information
Authors and Affiliations
Corresponding author
Electronic supplementary material
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Sanadhya, P., Agarwal, P., Khedia, J. et al. A Low-Affinity K+ Transporter AlHKT2;1 from Recretohalophyte Aeluropus lagopoides Confers Salt Tolerance in Yeast. Mol Biotechnol 57, 489–498 (2015). https://doi.org/10.1007/s12033-015-9842-9
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12033-015-9842-9