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Imran S, Oyama M, Horie R, Kobayashi NI, Costa A, Kumano R, Hirata C, Tran STH, Katsuhara M, Tanoi K, Kohchi T, Ishizaki K, Horie T. Distinct Functions of the Atypical Terminal Hydrophilic Domain of the HKT Transporter in the Liverwort Marchantia polymorpha. Plant Cell Physiol 2022; 63:802-816. [PMID: 35380735 DOI: 10.1093/pcp/pcac044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 03/29/2022] [Accepted: 04/03/2022] [Indexed: 06/14/2023]
Abstract
K+/Na+ homeostasis is important for land plants, particularly under salt stress. In this study, the structure and ion transport properties of the high-affinity K+ transporter (HKT) of the liverwort Marchantia polymorpha were investigated. Only one HKT gene, MpHKT1, was identified in the genome of M. polymorpha. Phylogenetic analysis of HKT proteins revealed that non-seed plants possess HKTs grouped into a clade independent of the other two clades including HKTs of angiosperms. A distinct long hydrophilic domain was found in the C-terminus of MpHKT1. Complementary DNA (cDNA) of truncated MpHKT1 (t-MpHKT1) encoding the MpHKT_Δ596-812 protein was used to examine the functions of the C-terminal domain. Both MpHKT1 transporters fused with enhanced green fluorescent protein at the N-terminus were localized to the plasma membrane when expressed in rice protoplasts. Two-electrode voltage clamp experiments using Xenopus laevis oocytes indicated that MpHKT1 mediated the transport of monovalent alkali cations with higher selectivity for Na+ and K+, but truncation of the C-terminal domain significantly reduced the transport activity with a decrease in the Na+ permeability. Overexpression of MpHKT1 or t-MpHKT1 in M. polymorpha conferred accumulation of higher Na+ levels and showed higher Na+ uptake rates, compared to those of wild-type plants; however, phenotypes with t-MpHKT1 were consistently weaker than those with MpHKT1. Together, these findings suggest that the hydrophilic C-terminal domain plays a unique role in the regulation of transport activity and ion selectivity of MpHKT1.
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Affiliation(s)
- Shahin Imran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046 Japan
- Department of Agronomy, Khulna Agricultural University, Khulna 9100, Bangladesh
| | - Masumi Oyama
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567 Japan
| | - Rie Horie
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567 Japan
| | - Natsuko I Kobayashi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan
| | - Alex Costa
- Department of Biosciences, University of Milan, Via Celoria 26, Milano 20133, Italy
- Institute of Biophysics, National Research Council of Italy (CNR), Milano 20133, Italy
| | - Ryosuke Kumano
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567 Japan
| | - Chiho Hirata
- Graduate School of Science, Kobe University, Kobe, Hyogo 657-8501 Japan
| | - Sen Thi Huong Tran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046 Japan
- Faculty of Agronomy, University of Agriculture and Forestry, Hue University, Hue, Thua Thien Hue 530000, Vietnam
| | - Maki Katsuhara
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046 Japan
| | - Keitaro Tanoi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan
| | - Takayuki Kohchi
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8502 Japan
| | | | - Tomoaki Horie
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567 Japan
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Imran S, Tsuchiya Y, Tran STH, Katsuhara M. Identification and Characterization of Rice OsHKT1;3 Variants. Plants (Basel) 2021; 10:plants10102006. [PMID: 34685816 PMCID: PMC8537747 DOI: 10.3390/plants10102006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 05/23/2023]
Abstract
In rice, the high-affinity K+ transporter, OsHKT1;3, functions as a Na+-selective transporter. mRNA variants of OsHKT1;3 have been reported previously, but their functions remain unknown. In this study, five OsHKT1;3 variants (V1-V5) were identified from japonica rice (Nipponbare) in addition to OsHKT1;3_FL. Absolute quantification qPCR analyses revealed that the transcript level of OsHKT1;3_FL was significantly higher than other variants in both the roots and shoots. Expression levels of OsHKT1;3_FL, and some variants, increased after 24 h of salt stress. Two electrode voltage clamp experiments in a heterologous expression system using Xenopus laevis oocytes revealed that oocytes expressing OsHKT1;3_FL and all of its variants exhibited smaller Na+ currents. The presented data, together with previous data, provide insights to understanding how OsHKT family members are involved in the mechanisms of ion homeostasis and salt tolerance in rice.
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Affiliation(s)
- Shahin Imran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan or (S.I.); (Y.T.); (S.T.H.T.)
- Department of Agronomy, Khulna Agricultural University, Khulna 9100, Bangladesh
| | - Yoshiyuki Tsuchiya
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan or (S.I.); (Y.T.); (S.T.H.T.)
| | - Sen Thi Huong Tran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan or (S.I.); (Y.T.); (S.T.H.T.)
- Faculty of Agronomy, University of Agriculture and Forestry, Hue University, Hue 530000, Vietnam
| | - Maki Katsuhara
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan or (S.I.); (Y.T.); (S.T.H.T.)
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Tran STH, Horie T, Imran S, Qiu J, McGaughey S, Byrt CS, Tyerman SD, Katsuhara M. A Survey of Barley PIP Aquaporin Ionic Conductance Reveals Ca 2+-Sensitive HvPIP2;8 Na + and K + Conductance. Int J Mol Sci 2020; 21:E7135. [PMID: 32992595 PMCID: PMC7582361 DOI: 10.3390/ijms21197135] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/25/2020] [Accepted: 09/25/2020] [Indexed: 02/02/2023] Open
Abstract
Some plasma membrane intrinsic protein (PIP) aquaporins can facilitate ion transport. Here we report that one of the 12 barley PIPs (PIP1 and PIP2) tested, HvPIP2;8, facilitated cation transport when expressed in Xenopus laevis oocytes. HvPIP2;8-associated ion currents were detected with Na+ and K+, but not Cs+, Rb+, or Li+, and was inhibited by Ba2+, Ca2+, and Cd2+ and to a lesser extent Mg2+, which also interacted with Ca2+. Currents were reduced in the presence of K+, Cs+, Rb+, or Li+ relative to Na+ alone. Five HvPIP1 isoforms co-expressed with HvPIP2;8 inhibited the ion conductance relative to HvPIP2;8 alone but HvPIP1;3 and HvPIP1;4 with HvPIP2;8 maintained the ion conductance at a lower level. HvPIP2;8 water permeability was similar to that of a C-terminal phosphorylation mimic mutant HvPIP2;8 S285D, but HvPIP2;8 S285D showed a negative linear correlation between water permeability and ion conductance that was modified by a kinase inhibitor treatment. HvPIP2;8 transcript abundance increased in barley shoot tissues following salt treatments in a salt-tolerant cultivar Haruna-Nijo, but not in salt-sensitive I743. There is potential for HvPIP2;8 to be involved in barley salt-stress responses, and HvPIP2;8 could facilitate both water and Na+/K+ transport activity, depending on the phosphorylation status.
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Affiliation(s)
- Sen Thi Huong Tran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan; (S.T.H.T.); (S.I.)
- Faculty of Agronomy, University of Agriculture and Forestry, Hue University, Hue 530000, Vietnam
| | - Tomoaki Horie
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1, Tokida, Ueda, Nagano 386-8567, Japan;
| | - Shahin Imran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan; (S.T.H.T.); (S.I.)
| | - Jiaen Qiu
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, Adelaide 5064, Australia; (J.Q.); (C.S.B.); (S.D.T.)
| | - Samantha McGaughey
- Research School of Biology, Australian National University, Canberra 2600, Australia;
| | - Caitlin S. Byrt
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, Adelaide 5064, Australia; (J.Q.); (C.S.B.); (S.D.T.)
- Research School of Biology, Australian National University, Canberra 2600, Australia;
| | - Stephen D. Tyerman
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, Adelaide 5064, Australia; (J.Q.); (C.S.B.); (S.D.T.)
| | - Maki Katsuhara
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki 710-0046, Japan; (S.T.H.T.); (S.I.)
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