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Plant Physiol. 2016 Jul;171(3):2112-26. doi: 10.1104/pp.16.00569. Epub 2016 May 9.

A Single Amino-Acid Substitution in the Sodium Transporter HKT1 Associated with Plant Salt Tolerance.

Author information

1
Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.).
2
Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.) djyun@gnu.ac.kr.

Abstract

A crucial prerequisite for plant growth and survival is the maintenance of potassium uptake, especially when high sodium surrounds the root zone. The Arabidopsis HIGH-AFFINITY K(+) TRANSPORTER1 (HKT1), and its homologs in other salt-sensitive dicots, contributes to salinity tolerance by removing Na(+) from the transpiration stream. However, TsHKT1;2, one of three HKT1 copies in Thellungiella salsuginea, a halophytic Arabidopsis relative, acts as a K(+) transporter in the presence of Na(+) in yeast (Saccharomyces cerevisiae). Amino-acid sequence comparisons indicated differences between TsHKT1;2 and most other published HKT1 sequences with respect to an Asp residue (D207) in the second pore-loop domain. Two additional T salsuginea and most other HKT1 sequences contain Asn (n) in this position. Wild-type TsHKT1;2 and altered AtHKT1 (AtHKT1(N-D)) complemented K(+)-uptake deficiency of yeast cells. Mutant hkt1-1 plants complemented with both AtHKT1(N) (-) (D) and TsHKT1;2 showed higher tolerance to salt stress than lines complemented by the wild-type AtHKT1 Electrophysiological analysis in Xenopus laevis oocytes confirmed the functional properties of these transporters and the differential selectivity for Na(+) and K(+) based on the n/d variance in the pore region. This change also dictated inward-rectification for Na(+) transport. Thus, the introduction of Asp, replacing Asn, in HKT1-type transporters established altered cation selectivity and uptake dynamics. We describe one way, based on a single change in a crucial protein that enabled some crucifer species to acquire improved salt tolerance, which over evolutionary time may have resulted in further changes that ultimately facilitated colonization of saline habitats.

PMID:
27208305
PMCID:
PMC4936583
DOI:
10.1104/pp.16.00569
[Indexed for MEDLINE]
Free PMC Article

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