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Gao Y, Zhao L, Wang B, Song Z, Jiao F, Wu X, Feng Z, Chen X, Gao L, Li Y. A tonoplast-localized TPK-type K + transporter (TPKa) regulates potassium accumulation in tobacco. Gene 2024; 926:148576. [PMID: 38763364 DOI: 10.1016/j.gene.2024.148576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 05/08/2024] [Accepted: 05/15/2024] [Indexed: 05/21/2024]
Abstract
Potassium ion (K+) is one of the most essential nutrients for the growth and development of tobacco (Nicotiana tabacum L.), however, the molecular regulation of K+ concentration in tobacco remains unclear. In this study, a two-pore K (TPK) channel gene NtTPKa was cloned from tobacco, and NtTPKa protein contains the unique K+ selection motif GYGD and its transmembrane region primarily locates in the tonoplast membrane. The expression of NtTPKa gene was significantly increased under low-potassium stress conditions. The concentrations of K+ in tobacco were significantly increased in the NtTPKa RNA interference lines and CRISPR/Cas9 knockout mutants. In addition, the transport of K+ by NtTPKa was validated using patch clamp technique, and the results showed that NtTPKa channel protein exclusively transported K+ in a concentration-dependent manner. Together, our results strongly suggested that NtTPKa is a key gene in maintaining K+ homeostasis in tobacco, and it could provide a new genetic resource for increasing the concentration of K+ in tobacco.
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Affiliation(s)
- Yulong Gao
- Yunnan Academy of Tobacco Agricultural Sciences/National Tobacco Genetic Engineering Research Center, Kunming, China
| | - Lu Zhao
- Yunnan Academy of Tobacco Agricultural Sciences/National Tobacco Genetic Engineering Research Center, Kunming, China
| | - Bingwu Wang
- Yunnan Academy of Tobacco Agricultural Sciences/National Tobacco Genetic Engineering Research Center, Kunming, China
| | - Zhongbang Song
- Yunnan Academy of Tobacco Agricultural Sciences/National Tobacco Genetic Engineering Research Center, Kunming, China
| | - Fangchan Jiao
- Yunnan Academy of Tobacco Agricultural Sciences/National Tobacco Genetic Engineering Research Center, Kunming, China
| | - Xingfu Wu
- Yunnan Academy of Tobacco Agricultural Sciences/National Tobacco Genetic Engineering Research Center, Kunming, China
| | - Zhiyu Feng
- Yunnan Academy of Tobacco Agricultural Sciences/National Tobacco Genetic Engineering Research Center, Kunming, China
| | - Xuejun Chen
- Yunnan Academy of Tobacco Agricultural Sciences/National Tobacco Genetic Engineering Research Center, Kunming, China
| | - Lifeng Gao
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Yongping Li
- Yunnan Academy of Tobacco Agricultural Sciences/National Tobacco Genetic Engineering Research Center, Kunming, China.
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2
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Nourmohammadi S, Henderson S, Ramesh S, Yool A. Characterization of human aquaporin ion channels in a yeast expression system as a tool for novel ion channel discovery. Biosci Rep 2024; 44:BSR20240542. [PMID: 39069912 PMCID: PMC11358751 DOI: 10.1042/bsr20240542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 07/15/2024] [Accepted: 07/26/2024] [Indexed: 07/30/2024] Open
Abstract
Aquaporin (AQP) channels found in all domains of life are transmembrane proteins which mediate passive transport of water, glycerol, signaling molecules, metabolites, and charged solutes. Discovery of new classes of ion-conducting AQP channels has been slow, likely reflecting time- and labor-intensive methods required for traditional electrophysiology. Work here defines a sensitive mass-throughput system for detecting AQP ion channels, identified by rescue of cell growth in the K+-transport-defective yeast strain CY162 following genetic complementation with heterologously expressed cation-permeable channels, using the well characterized human AQP1 channel for proof of concept. Results showed AQP1 conferred transmembrane permeability to cations which rescued survival in CY162 yeast. Comprehensive testing showed that growth response properties fully recapitulated AQP1 pharmacological agonist and antagonist profiles for activation, inhibition, dose-dependence, and structure-function relationships, demonstrating validity of the yeast screening tool for AQP channel identification and drug discovery efforts. This method also provided new information on divalent cation blockers of AQP1, pH sensitivity of antagonists, and ion permeability of human AQP6. Site-directed mutagenesis of AQP1 channel regulatory domains confirmed that yeast growth rescue was mediated by the introduced channels. Optical monitoring with a lithium-sensitive photoswitchable probe in living cells independently demonstrated monovalent cation permeability of AQP1 channels in yeast plasma membrane. Ion channel properties of AQP1 expressed in yeast were consistent with those of AQP1 expressed in Xenopus laevis oocyte and K+-transport defective Escherichia coli. Outcomes here establish a powerful new approach for efficient screening of phylogenetically diverse AQPs for yet untested functions as cation channels.
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Affiliation(s)
- Saeed Nourmohammadi
- School of Biomedicine, Faculty of Health and Medical Sciences, and the Institute for Photonics and Advanced Sensing, University of Adelaide, Adelaide, SA 5005, Australia
| | - Sam W. Henderson
- School of Biomedicine, Faculty of Health and Medical Sciences, and the Institute for Photonics and Advanced Sensing, University of Adelaide, Adelaide, SA 5005, Australia
| | - Sunita A. Ramesh
- Biological Sciences, College of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia
| | - Andrea J. Yool
- School of Biomedicine, Faculty of Health and Medical Sciences, and the Institute for Photonics and Advanced Sensing, University of Adelaide, Adelaide, SA 5005, Australia
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Blatt MR. A charged existence: A century of transmembrane ion transport in plants. PLANT PHYSIOLOGY 2024; 195:79-110. [PMID: 38163639 PMCID: PMC11060664 DOI: 10.1093/plphys/kiad630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 11/01/2023] [Indexed: 01/03/2024]
Abstract
If the past century marked the birth of membrane transport as a focus for research in plants, the past 50 years has seen the field mature from arcane interest to a central pillar of plant physiology. Ion transport across plant membranes accounts for roughly 30% of the metabolic energy consumed by a plant cell, and it underpins virtually every aspect of plant biology, from mineral nutrition, cell expansion, and development to auxin polarity, fertilization, plant pathogen defense, and senescence. The means to quantify ion flux through individual transporters, even single channel proteins, became widely available as voltage clamp methods expanded from giant algal cells to the fungus Neurospora crassa in the 1970s and the cells of angiosperms in the 1980s. Here, I touch briefly on some key aspects of the development of modern electrophysiology with a focus on the guard cells of stomata, now without dispute the premier plant cell model for ion transport and its regulation. Guard cells have proven to be a crucible for many technical and conceptual developments that have since emerged into the mainstream of plant science. Their study continues to provide fundamental insights and carries much importance for the global challenges that face us today.
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Affiliation(s)
- Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
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Dabravolski SA, Isayenkov SV. Recent updates on the physiology and evolution of plant TPK/KCO channels. FUNCTIONAL PLANT BIOLOGY : FPB 2023; 50:17-28. [PMID: 36220140 DOI: 10.1071/fp22117] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
Plant vacuoles are the main cellular reservoirs to store K+ . The vacuolar K+ channels play a pivotal role in K+ exchange between cytosol and vacuolar sap. Among vacuolar K+ transporters, the Two Pore Potassium Channels (TPKs) are highly selective K+ channels present in most or all plant vacuoles and could be involved in various plant stress responses and developmental processes. Although the majority of TPK members have a vacuolar specialisation, some TPKs display different membrane localisation including the plasma membrane, tonoplast of protein storage vacuoles and probably chloroplast membranes. The functional properties as well as physiological roles of TPKs remains largely unexplored. In this review, we have collected recent data about the physiology, structure, functionality and evolution of TPK/KCO3 channels. We also critically evaluate the latest findings on the biological role, physiological functions, and regulation of TPK/KCO3 channels in relation to their structure and phylogenetic position. The possible role of TPK/KCO3 channels in plant tolerance to various abiotic stresses is summarised, and the future priority directions for TPK/KCO3 studies are addressed.
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Affiliation(s)
- Siarhei A Dabravolski
- Department of Biotechnology Engineering, ORT Braude College, Snunit 51, P.O. Box 78, Karmiel 2161002, Israel
| | - Stanislav V Isayenkov
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China; and Department of Plant Food Products and Biofortification, Institute of Food Biotechnology and Genomics NAS of Ukraine, Kyiv, Ukraine
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Liu JN, Fang H, Liang Q, Dong Y, Wang C, Yan L, Ma X, Zhou R, Lang X, Gai S, Wang L, Xu S, Yang KQ, Wu D. Genomic analyses provide insights into the evolution and salinity adaptation of halophyte Tamarix chinensis. Gigascience 2022; 12:giad053. [PMID: 37494283 PMCID: PMC10370455 DOI: 10.1093/gigascience/giad053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/09/2023] [Accepted: 06/29/2023] [Indexed: 07/28/2023] Open
Abstract
BACKGROUND The woody halophyte Tamarix chinensis is a pioneer tree species in the coastal wetland ecosystem of northern China, exhibiting high resistance to salt stress. However, the genetic information underlying salt tolerance in T. chinensis remains to be seen. Here we present a genomic investigation of T. chinensis to elucidate the underlying mechanism of its high resistance to salinity. RESULTS Using a combination of PacBio and high-throughput chromosome conformation capture data, a chromosome-level T. chinensis genome was assembled with a size of 1.32 Gb and scaffold N50 of 110.03 Mb. Genome evolution analyses revealed that T. chinensis significantly expanded families of HAT and LIMYB genes. Whole-genome and tandem duplications contributed to the expansion of genes associated with the salinity adaptation of T. chinensis. Transcriptome analyses were performed on root and shoot tissues during salt stress and recovery, and several hub genes responding to salt stress were identified. WRKY33/40, MPK3/4, and XBAT31 were critical in responding to salt stress during early exposure, while WRKY40, ZAT10, AHK4, IRX9, and CESA4/8 were involved in responding to salt stress during late stress and recovery. In addition, PER7/27/57/73 encoding class III peroxidase and MCM3/4/5/7 encoding DNA replication licensing factor maintained up/downregulation during salt stress and recovery stages. CONCLUSIONS The results presented here reveal the genetic mechanisms underlying salt adaptation in T. chinensis, thus providing important genomic resources for evolutionary studies on tamarisk and plant salt tolerance genetic improvement.
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Affiliation(s)
- Jian Ning Liu
- College of Forestry, Shandong Agricultural University, Taian 271018, China
| | - Hongcheng Fang
- College of Forestry, Shandong Agricultural University, Taian 271018, China
- State Forestry and Grassland Administration Key Laboratory of Silviculture in the Downstream Areas of the Yellow River, Shandong Agricultural University, Taian 271018, China
- Shandong Taishan Forest Ecosystem Research Station, Shandong Agricultural University, Taian 271018, China
| | - Qiang Liang
- College of Forestry, Shandong Agricultural University, Taian 271018, China
- State Forestry and Grassland Administration Key Laboratory of Silviculture in the Downstream Areas of the Yellow River, Shandong Agricultural University, Taian 271018, China
- Shandong Taishan Forest Ecosystem Research Station, Shandong Agricultural University, Taian 271018, China
| | - Yuhui Dong
- College of Forestry, Shandong Agricultural University, Taian 271018, China
- State Forestry and Grassland Administration Key Laboratory of Silviculture in the Downstream Areas of the Yellow River, Shandong Agricultural University, Taian 271018, China
- Shandong Taishan Forest Ecosystem Research Station, Shandong Agricultural University, Taian 271018, China
| | - Changxi Wang
- College of Forestry, Shandong Agricultural University, Taian 271018, China
| | - Liping Yan
- Shandong Provincial Academy of Forestry, Jinan 250014, China
| | - Xinmei Ma
- College of Forestry, Shandong Agricultural University, Taian 271018, China
| | - Rui Zhou
- College of Forestry, Shandong Agricultural University, Taian 271018, China
| | - Xinya Lang
- College of Forestry, Shandong Agricultural University, Taian 271018, China
| | - Shasha Gai
- College of Forestry, Shandong Agricultural University, Taian 271018, China
| | - Lichang Wang
- College of Forestry, Shandong Agricultural University, Taian 271018, China
| | - Shengyi Xu
- College of Forestry, Shandong Agricultural University, Taian 271018, China
| | - Ke Qiang Yang
- College of Forestry, Shandong Agricultural University, Taian 271018, China
- State Forestry and Grassland Administration Key Laboratory of Silviculture in the Downstream Areas of the Yellow River, Shandong Agricultural University, Taian 271018, China
- Shandong Taishan Forest Ecosystem Research Station, Shandong Agricultural University, Taian 271018, China
| | - Dejun Wu
- Shandong Provincial Academy of Forestry, Jinan 250014, China
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6
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Dabravolski SA, Isayenkov SV. New Insights into Plant TPK Ion Channel Evolution. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10112328. [PMID: 34834689 PMCID: PMC8619664 DOI: 10.3390/plants10112328] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/27/2021] [Accepted: 10/27/2021] [Indexed: 05/14/2023]
Abstract
Potassium (K) is a crucial element of plant nutrition, involved in many physiological and molecular processes. K+ membrane transporters are playing a pivotal role in K+ transport and tissue distribution as well as in various plant stress responses and developmental processes. Two-pore K+-channels (TPKs) are essential to maintain plant K+ homeostasis and are mainly involved in potassium transport from the vacuoles to the cytosol. Besides vacuolar specialization, some TPK members display different membrane localization including plasma membrane, protein storage vacuole membrane, and probably the organelles. In this manuscript, we elucidate the evolution of the voltage-independent TPK (two-pore K+-channels) family, which could be represented in some species by one pore, K+-inward rectifier (Kir)-like channels. A comprehensive investigation of existing databases and application of modern bioinformatic tools allowed us to make a detailed phylogenetic inventory of TPK/KCO3 (KCO: potassium channel, outward rectifying) channels through many taxa and gain insight into the evolutionary origin of TPK family proteins. Our results reveal the fundamental evolutional difference between the first and second pores, traced throughout multiple taxa variations in the ion selection filter motif, presence of thansposon, and methylation site in the proximity of some KCO members and suggest virus-mediated horizontal transfer of a KCO3-like ancestor by viruses. Additionally, we suggest several interconnected hypotheses to explain the obtained results and provide a theoretical background for future experimental validation.
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Affiliation(s)
- Siarhei A. Dabravolski
- Department of Clinical Diagnostics, Vitebsk State Academy of Veterinary Medicine [UO VGAVM], 21002 Vitebsk, Belarus;
| | - Stanislav V. Isayenkov
- International Research Center for Environmental Membrane Biology, Foshan University, Foshan 528000, China
- Department of Plant Food Products and Biofortification, Institute of Food Biotechnology and Genomics NAS of Ukraine, 04123 Kyiv, Ukraine
- Correspondence:
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7
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Lhamo D, Wang C, Gao Q, Luan S. Recent Advances in Genome-wide Analyses of Plant Potassium Transporter Families. Curr Genomics 2021; 22:164-180. [PMID: 34975289 PMCID: PMC8640845 DOI: 10.2174/1389202922666210225083634] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/30/2020] [Accepted: 01/26/2021] [Indexed: 12/19/2022] Open
Abstract
Plants require potassium (K+) as a macronutrient to support numerous physiological processes. Understanding how this nutrient is transported, stored, and utilized within plants is crucial for breeding crops with high K+ use efficiency. As K+ is not metabolized, cross-membrane transport becomes a rate-limiting step for efficient distribution and utilization in plants. Several K+ transporter families, such as KUP/HAK/KT and KEA transporters and Shaker-like and TPK channels, play dominant roles in plant K+ transport processes. In this review, we provide a comprehensive contemporary overview of our knowledge about these K+ transporter families in angiosperms, with a major focus on the genome-wide identification of K+ transporter families, subcellular localization, spatial expression, function and regulation. We also expanded the genome-wide search for the K+ transporter genes and examined their tissue-specific expression in Camelina sativa, a polyploid oil-seed crop with a potential to adapt to marginal lands for biofuel purposes and contribution to sustainable agriculture. In addition, we present new insights and emphasis on the study of K+ transporters in polyploids in an effort to generate crops with high K+ Utilization Efficiency (KUE).
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Affiliation(s)
- Dhondup Lhamo
- 1Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; 2School of Life Sciences, Northwest University, Xi'an 710069, China
| | - Chao Wang
- 1Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; 2School of Life Sciences, Northwest University, Xi'an 710069, China
| | - Qifei Gao
- 1Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; 2School of Life Sciences, Northwest University, Xi'an 710069, China
| | - Sheng Luan
- 1Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; 2School of Life Sciences, Northwest University, Xi'an 710069, China
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8
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Nefissi Ouertani R, Arasappan D, Abid G, Ben Chikha M, Jardak R, Mahmoudi H, Mejri S, Ghorbel A, Ruhlman TA, Jansen RK. Transcriptomic Analysis of Salt-Stress-Responsive Genes in Barley Roots and Leaves. Int J Mol Sci 2021; 22:8155. [PMID: 34360920 PMCID: PMC8348758 DOI: 10.3390/ijms22158155] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 12/03/2022] Open
Abstract
Barley is characterized by a rich genetic diversity, making it an important model for studies of salinity response with great potential for crop improvement. Moreover, salt stress severely affects barley growth and development, leading to substantial yield loss. Leaf and root transcriptomes of a salt-tolerant Tunisian landrace (Boulifa) exposed to 2, 8, and 24 h salt stress were compared with pre-exposure plants to identify candidate genes and pathways underlying barley's response. Expression of 3585 genes was upregulated and 5586 downregulated in leaves, while expression of 13,200 genes was upregulated and 10,575 downregulated in roots. Regulation of gene expression was severely impacted in roots, highlighting the complexity of salt stress response mechanisms in this tissue. Functional analyses in both tissues indicated that response to salt stress is mainly achieved through sensing and signaling pathways, strong transcriptional reprograming, hormone osmolyte and ion homeostasis stabilization, increased reactive oxygen scavenging, and activation of transport and photosynthesis systems. A number of candidate genes involved in hormone and kinase signaling pathways, as well as several transcription factor families and transporters, were identified. This study provides valuable information on early salt-stress-responsive genes in roots and leaves of barley and identifies several important players in salt tolerance.
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Affiliation(s)
- Rim Nefissi Ouertani
- Laboratory of Plant Molecular Physiology, Center of Biotechnology of Borj Cedria, B.P. 901, Hammam-Lif 2050, Tunisia; (R.N.O.); (M.B.C.); (R.J.); (S.M.); (A.G.)
| | - Dhivya Arasappan
- Center for Biomedical Research Support, University of Texas at Austin, Austin, TX 78712, USA;
| | - Ghassen Abid
- Laboratory of Legumes and Sustainable Agrosystems, Center of Biotechnology of Borj Cedria, B.P. 901, Hammam-Lif 2050, Tunisia;
| | - Mariem Ben Chikha
- Laboratory of Plant Molecular Physiology, Center of Biotechnology of Borj Cedria, B.P. 901, Hammam-Lif 2050, Tunisia; (R.N.O.); (M.B.C.); (R.J.); (S.M.); (A.G.)
| | - Rahma Jardak
- Laboratory of Plant Molecular Physiology, Center of Biotechnology of Borj Cedria, B.P. 901, Hammam-Lif 2050, Tunisia; (R.N.O.); (M.B.C.); (R.J.); (S.M.); (A.G.)
| | - Henda Mahmoudi
- International Center for Biosaline Agriculture, Dubai 00000, United Arab Emirates;
| | - Samiha Mejri
- Laboratory of Plant Molecular Physiology, Center of Biotechnology of Borj Cedria, B.P. 901, Hammam-Lif 2050, Tunisia; (R.N.O.); (M.B.C.); (R.J.); (S.M.); (A.G.)
| | - Abdelwahed Ghorbel
- Laboratory of Plant Molecular Physiology, Center of Biotechnology of Borj Cedria, B.P. 901, Hammam-Lif 2050, Tunisia; (R.N.O.); (M.B.C.); (R.J.); (S.M.); (A.G.)
| | - Tracey A. Ruhlman
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA;
| | - Robert K. Jansen
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA;
- Biotechnology Research Group, Department of Biological Sciences, Faculty of Science, King Abdulaziz University (KAU), Jeddah 21589, Saudi Arabia
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9
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Lhamo D, Luan S. Potential Networks of Nitrogen-Phosphorus-Potassium Channels and Transporters in Arabidopsis Roots at a Single Cell Resolution. FRONTIERS IN PLANT SCIENCE 2021; 12:689545. [PMID: 34220911 PMCID: PMC8242960 DOI: 10.3389/fpls.2021.689545] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/24/2021] [Indexed: 05/08/2023]
Abstract
Nitrogen (N), phosphorus (P), and potassium (K) are three major macronutrients essential for plant life. These nutrients are acquired and transported by several large families of transporters expressed in plant roots. However, it remains largely unknown how these transporters are distributed in different cell-types that work together to transfer the nutrients from the soil to different layers of root cells and eventually reach vasculature for massive flow. Using the single cell transcriptomics data from Arabidopsis roots, we profiled the transcriptional patterns of putative nutrient transporters in different root cell-types. Such analyses identified a number of uncharacterized NPK transporters expressed in the root epidermis to mediate NPK uptake and distribution to the adjacent cells. Some transport genes showed cortex- and endodermis-specific expression to direct the nutrient flow toward the vasculature. For long-distance transport, a variety of transporters were shown to express and potentially function in the xylem and phloem. In the context of subcellular distribution of mineral nutrients, the NPK transporters at subcellular compartments were often found to show ubiquitous expression patterns, which suggests function in house-keeping processes. Overall, these single cell transcriptomic analyses provide working models of nutrient transport from the epidermis across the cortex to the vasculature, which can be further tested experimentally in the future.
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Affiliation(s)
- Dhondup Lhamo
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
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10
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Pottosin I, Olivas-Aguirre M, Dobrovinskaya O, Zepeda-Jazo I, Shabala S. Modulation of Ion Transport Across Plant Membranes by Polyamines: Understanding Specific Modes of Action Under Stress. FRONTIERS IN PLANT SCIENCE 2021; 11:616077. [PMID: 33574826 PMCID: PMC7870501 DOI: 10.3389/fpls.2020.616077] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 12/14/2020] [Indexed: 05/20/2023]
Abstract
This work critically discusses the direct and indirect effects of natural polyamines and their catabolites such as reactive oxygen species and γ-aminobutyric acid on the activity of key plant ion-transporting proteins such as plasma membrane H+ and Ca2+ ATPases and K+-selective and cation channels in the plasma membrane and tonoplast, in the context of their involvement in stress responses. Docking analysis predicts a distinct binding for putrescine and longer polyamines within the pore of the vacuolar TPC1/SV channel, one of the key determinants of the cell ionic homeostasis and signaling under stress conditions, and an additional site for spermine, which overlaps with the cytosolic regulatory Ca2+-binding site. Several unresolved problems are summarized, including the correct estimates of the subcellular levels of polyamines and their catabolites, their unexplored effects on nucleotide-gated and glutamate receptor channels of cell membranes and Ca2+-permeable and K+-selective channels in the membranes of plant mitochondria and chloroplasts, and pleiotropic mechanisms of polyamines' action on H+ and Ca2+ pumps.
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Affiliation(s)
- Igor Pottosin
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China
- Biomedical Center, University of Colima, Colima, Mexico
| | | | | | - Isaac Zepeda-Jazo
- Food Genomics Department, Universidad de La Ciénega del Estado de Michoacán de Ocampo, Sahuayo, Mexico
| | - Sergey Shabala
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Hobart, TAS, Australia
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11
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Vigani G, Costa A. Harnessing the new emerging imaging technologies to uncover the role of Ca 2+ signalling in plant nutrient homeostasis. PLANT, CELL & ENVIRONMENT 2019; 42:2885-2901. [PMID: 31286524 DOI: 10.1111/pce.13611] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/03/2019] [Accepted: 07/05/2019] [Indexed: 05/26/2023]
Abstract
Increasing crop yields by using ecofriendly practices is of high priority to tackle problems regarding food security and malnutrition worldwide. A sustainable crop production requires a limited use of fertilizer and the employment of plant varieties with improved ability to acquire nutrients from soil. To reach these goals, the scientific community aims to understand plant nutrients homeostasis by deciphering the nutrient sensing and signalling mechanisms of plants. Several lines of evidence about the involvement of Ca2+ as the signal of an impaired nutrient availability have been reported. Ca2+ signalling is a tightly regulated process that requires specific protein toolkits to perceive external stimuli and to induce the specific responses in the plant needed to survive. Here, we summarize both older and recent findings concerning the involvement of Ca2+ signalling in the homeostasis of nutrients. In this review, we present new emerging technologies, based on the use of genetically encoded Ca2+ sensors and advanced microscopy, which offer the chance to perform in planta analyses of Ca2+ dynamics at cellular resolution. The harnessing of these technologies with different genetic backgrounds and subjected to different nutritional stresses will provide important insights to the still little-known mechanisms of nutrient sensing in plants.
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Affiliation(s)
- Gianpiero Vigani
- Department of Life Sciences and Systems Biology, University of Turin, Turin, 10135, Italy
| | - Alex Costa
- Department of Biosciences, University of Milan, Milan, 20133, Italy
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12
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Locascio A, Andrés-Colás N, Mulet JM, Yenush L. Saccharomyces cerevisiae as a Tool to Investigate Plant Potassium and Sodium Transporters. Int J Mol Sci 2019; 20:E2133. [PMID: 31052176 PMCID: PMC6539216 DOI: 10.3390/ijms20092133] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 04/26/2019] [Accepted: 04/29/2019] [Indexed: 12/20/2022] Open
Abstract
Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for plants and its concentration must be maintained at approximately 150 mM in the plant cell cytoplasm including under circumstances where its concentration is much lower in soil. On the other hand, sodium must be extruded from the plant or accumulated either in the vacuole or in specific plant structures. Maintaining a high intracellular K+/Na+ ratio under adverse environmental conditions or in the presence of salt is essential to maintain cellular homeostasis and to avoid toxicity. The baker's yeast, Saccharomyces cerevisiae, has been used to identify and characterize participants in potassium and sodium homeostasis in plants for many years. Its utility resides in the fact that the electric gradient across the membrane and the vacuoles is similar to plants. Most plant proteins can be expressed in yeast and are functional in this unicellular model system, which allows for productive structure-function studies for ion transporting proteins. Moreover, yeast can also be used as a high-throughput platform for the identification of genes that confer stress tolerance and for the study of protein-protein interactions. In this review, we summarize advances regarding potassium and sodium transport that have been discovered using the yeast model system, the state-of-the-art of the available techniques and the future directions and opportunities in this field.
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Affiliation(s)
- Antonella Locascio
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
| | - Nuria Andrés-Colás
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
| | - José Miguel Mulet
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
| | - Lynne Yenush
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
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The Complex Fine-Tuning of K⁺ Fluxes in Plants in Relation to Osmotic and Ionic Abiotic Stresses. Int J Mol Sci 2019; 20:ijms20030715. [PMID: 30736441 PMCID: PMC6387338 DOI: 10.3390/ijms20030715] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 01/17/2019] [Accepted: 01/29/2019] [Indexed: 12/19/2022] Open
Abstract
As the main cation in plant cells, potassium plays an essential role in adaptive responses, especially through its involvement in osmotic pressure and membrane potential adjustments. K+ homeostasis must, therefore, be finely controlled. As a result of different abiotic stresses, especially those resulting from global warming, K⁺ fluxes and plant distribution of this ion are disturbed. The hormone abscisic acid (ABA) is a key player in responses to these climate stresses. It triggers signaling cascades that ultimately lead to modulation of the activities of K⁺ channels and transporters. After a brief overview of transcriptional changes induced by abiotic stresses, this review deals with the post-translational molecular mechanisms in different plant organs, in Arabidopsis and species of agronomical interest, triggering changes in K⁺ uptake from the soil, K⁺ transport and accumulation throughout the plant, and stomatal regulation. These modifications involve phosphorylation/dephosphorylation mechanisms, modifications of targeting, and interactions with regulatory partner proteins. Interestingly, many signaling pathways are common to K⁺ and Cl-/NO3- counter-ion transport systems. These cross-talks are also addressed.
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14
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Luan M, Tang RJ, Tang Y, Tian W, Hou C, Zhao F, Lan W, Luan S. Transport and homeostasis of potassium and phosphate: limiting factors for sustainable crop production. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3091-3105. [PMID: 27965362 DOI: 10.1093/jxb/erw444] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Potassium (K) and phosphate (Pi) are both macronutrients essential for plant growth and crop production, but the unrenewable resources of phosphorus rock and potash have become limiting factors for food security. One critical measure to help solve this problem is to improve nutrient use efficiency (NUE) in plants by understanding and engineering genetic networks for ion uptake, translocation, and storage. Plants have evolved multiple systems to adapt to various nutrient conditions for growth and production. Within the NUE networks, transport proteins and their regulators are the primary players for maintaining nutrient homeostasis and could be utilized to engineer high NUE traits in crop plants. A large number of publications have detailed K+ and Pi transport proteins in plants over the past three decades. Meanwhile, the discovery and validation of their regulatory mechanisms are fast-track topics for research. Here, we provide an overview of K+ and Pi transport proteins and their regulatory mechanisms, which participate in the uptake, translocation, storage, and recycling of these nutrients in plants.
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Affiliation(s)
- Mingda Luan
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, School of Life Sciences, Nanjing University, Nanjing 210093, PR China
| | - Ren-Jie Tang
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - Yumei Tang
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, School of Life Sciences, Nanjing University, Nanjing 210093, PR China
| | - Wang Tian
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - Congong Hou
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - Fugeng Zhao
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, School of Life Sciences, Nanjing University, Nanjing 210093, PR China
| | - Wenzhi Lan
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, School of Life Sciences, Nanjing University, Nanjing 210093, PR China
| | - Sheng Luan
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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15
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Jezek M, Blatt MR. The Membrane Transport System of the Guard Cell and Its Integration for Stomatal Dynamics. PLANT PHYSIOLOGY 2017; 174:487-519. [PMID: 28408539 PMCID: PMC5462021 DOI: 10.1104/pp.16.01949] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 04/11/2017] [Indexed: 05/17/2023]
Abstract
Stomatal guard cells are widely recognized as the premier plant cell model for membrane transport, signaling, and homeostasis. This recognition is rooted in half a century of research into ion transport across the plasma and vacuolar membranes of guard cells that drive stomatal movements and the signaling mechanisms that regulate them. Stomatal guard cells surround pores in the epidermis of plant leaves, controlling the aperture of the pore to balance CO2 entry into the leaf for photosynthesis with water loss via transpiration. The position of guard cells in the epidermis is ideally suited for cellular and subcellular research, and their sensitivity to endogenous signals and environmental stimuli makes them a primary target for physiological studies. Stomata underpin the challenges of water availability and crop production that are expected to unfold over the next 20 to 30 years. A quantitative understanding of how ion transport is integrated and controlled is key to meeting these challenges and to engineering guard cells for improved water use efficiency and agricultural yields.
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Affiliation(s)
- Mareike Jezek
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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16
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Kleist TJ, Luan S. Constant change: dynamic regulation of membrane transport by calcium signalling networks keeps plants in tune with their environment. PLANT, CELL & ENVIRONMENT 2016; 39:467-481. [PMID: 26139029 DOI: 10.1111/pce.12599] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 05/20/2015] [Accepted: 05/21/2015] [Indexed: 06/04/2023]
Abstract
Despite substantial variation and irregularities in their environment, plants must conform to spatiotemporal demands on the molecular composition of their cytosol. Cell membranes are the major interface between organisms and their environment and the basis for controlling the contents and intracellular organization of the cell. Membrane transport proteins (MTPs) govern the flow of molecules across membranes, and their activities are closely monitored and regulated by cell signalling networks. By continuously adjusting MTP activities, plants can mitigate the effects of environmental perturbations, but effective implementation of this strategy is reliant on precise coordination among transport systems that reside in distinct cell types and membranes. Here, we examine the role of calcium signalling in the coordination of membrane transport, with an emphasis on potassium transport. Potassium is an exceptionally abundant and mobile ion in plants, and plant potassium transport has been intensively studied for decades. Classic and recent studies have underscored the importance of calcium in plant environmental responses and membrane transport regulation. In reviewing recent advances in our understanding of the coding and decoding of calcium signals, we highlight established and emerging roles of calcium signalling in coordinating membrane transport among multiple subcellular locations and distinct transport systems in plants, drawing examples from the CBL-CIPK signalling network. By synthesizing classical studies and recent findings, we aim to provide timely insights on the role of calcium signalling networks in the modulation of membrane transport and its importance in plant environmental responses.
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Affiliation(s)
- Thomas J Kleist
- University of California, Berkeley, Department of Plant & Microbial Biology, Berkeley, CA, 94720, USA
| | - Sheng Luan
- University of California, Berkeley, Department of Plant & Microbial Biology, Berkeley, CA, 94720, USA
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17
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Wilson RS, Swatek KN, Thelen JJ. Regulation of the Regulators: Post-Translational Modifications, Subcellular, and Spatiotemporal Distribution of Plant 14-3-3 Proteins. FRONTIERS IN PLANT SCIENCE 2016; 7:611. [PMID: 27242818 PMCID: PMC4860396 DOI: 10.3389/fpls.2016.00611] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 04/21/2016] [Indexed: 05/18/2023]
Abstract
14-3-3 proteins bind to and modulate the activity of phosphorylated proteins that regulate a variety of metabolic processes in eukaryotes. Multiple 14-3-3 isoforms are expressed in most organisms and display redundancy in both sequence and function. Plants contain the largest number of 14-3-3 isoforms. For example, Arabidopsis thaliana contains thirteen 14-3-3 genes, each of which is expressed. Interest in the plant 14-3-3 field has swelled over the past decade, largely due to the vast number of possibilities for 14-3-3 metabolic regulation. As the field progresses, it is essential to understand these proteins' activities at both the spatiotemporal and subcellular levels. This review summarizes current knowledge of 14-3-3 proteins in plants, including 14-3-3 interactions, regulatory functions, isoform specificity, and post-translational modifications. We begin with a historical overview and structural analysis of 14-3-3 proteins, which describes the basic principles of 14-3-3 function, and then discuss interactions and regulatory effects of plant 14-3-3 proteins in specific tissues and subcellular compartments. We conclude with a summary of 14-3-3 phosphorylation and current knowledge of the functional effects of this modification in plants.
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18
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Wang Y, Dindas J, Rienmüller F, Krebs M, Waadt R, Schumacher K, Wu WH, Hedrich R, Roelfsema MRG. Cytosolic Ca(2+) Signals Enhance the Vacuolar Ion Conductivity of Bulging Arabidopsis Root Hair Cells. MOLECULAR PLANT 2015; 8:1665-74. [PMID: 26232520 DOI: 10.1016/j.molp.2015.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 06/16/2015] [Accepted: 07/21/2015] [Indexed: 05/23/2023]
Abstract
Plant cell expansion depends on the uptake of solutes across the plasma membrane and their storage within the vacuole. In contrast to the well-studied plasma membrane, little is known about the regulation of ion transport at the vacuolar membrane. We therefore established an experimental approach to study vacuolar ion transport in intact Arabidopsis root cells, with multi-barreled microelectrodes. The subcellular position of electrodes was detected by imaging current-injected fluorescent dyes. Comparison of measurements with electrodes in the cytosol and vacuole revealed an average vacuolar membrane potential of -31 mV. Voltage clamp recordings of single vacuoles resolved the activity of voltage-independent and slowly deactivating channels. In bulging root hairs that express the Ca(2+) sensor R-GECO1, rapid elevation of the cytosolic Ca(2+) concentration was observed, after impalement with microelectrodes, or injection of the Ca(2+) chelator BAPTA. Elevation of the cytosolic Ca(2+) level stimulated the activity of voltage-independent channels in the vacuolar membrane. Likewise, the vacuolar ion conductance was enhanced during a sudden increase of the cytosolic Ca(2+) level in cells injected with fluorescent Ca(2+) indicator FURA-2. These data thus show that cytosolic Ca(2+) signals can rapidly activate vacuolar ion channels, which may prevent rupture of the vacuolar membrane, when facing mechanical forces.
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Affiliation(s)
- Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Julian Dindas
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany
| | - Florian Rienmüller
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany
| | - Melanie Krebs
- Centre for Organismal Studies, Developmental Biology of Plants, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Rainer Waadt
- Centre for Organismal Studies, Developmental Biology of Plants, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Karin Schumacher
- Centre for Organismal Studies, Developmental Biology of Plants, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Wei-Hua Wu
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Rainer Hedrich
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany; College of Science, King Saud University (KSU), Riyadh, Saudi Arabia
| | - M Rob G Roelfsema
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany.
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19
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Isayenkov SV, Maathuis FJM. The expression of rice vacuolar TPK channels genes restores potassium uptake in E. coli mutant strain LB2003. CYTOL GENET+ 2015. [DOI: 10.3103/s0095452715010053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Cotelle V, Leonhardt N. 14-3-3 Proteins in Guard Cell Signaling. FRONTIERS IN PLANT SCIENCE 2015; 6:1210. [PMID: 26858725 PMCID: PMC4729941 DOI: 10.3389/fpls.2015.01210] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/15/2015] [Indexed: 05/19/2023]
Abstract
Guard cells are specialized cells located at the leaf surface delimiting pores which control gas exchanges between the plant and the atmosphere. To optimize the CO2 uptake necessary for photosynthesis while minimizing water loss, guard cells integrate environmental signals to adjust stomatal aperture. The size of the stomatal pore is regulated by movements of the guard cells driven by variations in their volume and turgor. As guard cells perceive and transduce a wide array of environmental cues, they provide an ideal system to elucidate early events of plant signaling. Reversible protein phosphorylation events are known to play a crucial role in the regulation of stomatal movements. However, in some cases, phosphorylation alone is not sufficient to achieve complete protein regulation, but is necessary to mediate the binding of interactors that modulate protein function. Among the phosphopeptide-binding proteins, the 14-3-3 proteins are the best characterized in plants. The 14-3-3s are found as multiple isoforms in eukaryotes and have been shown to be involved in the regulation of stomatal movements. In this review, we describe the current knowledge about 14-3-3 roles in the regulation of their binding partners in guard cells: receptors, ion pumps, channels, protein kinases, and some of their substrates. Regulation of these targets by 14-3-3 proteins is discussed and related to their function in guard cells during stomatal movements in response to abiotic or biotic stresses.
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Affiliation(s)
- Valérie Cotelle
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPSCastanet-Tolosan, France
- *Correspondence: Valérie Cotelle,
| | - Nathalie Leonhardt
- UMR7265, Laboratoire de Biologie du Développement des Plantes, Service de Biologie Végétale et de Microbiologie Environnementales, Institut de Biologie Environnementale et Biotechnologie, CNRS–CEA–Université Aix-MarseilleSaint-Paul-lez-Durance, France
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21
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Cotelle V, Leonhardt N. 14-3-3 Proteins in Guard Cell Signaling. FRONTIERS IN PLANT SCIENCE 2015. [PMID: 26858725 DOI: 10.3389/fpis.2015.01210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Guard cells are specialized cells located at the leaf surface delimiting pores which control gas exchanges between the plant and the atmosphere. To optimize the CO2 uptake necessary for photosynthesis while minimizing water loss, guard cells integrate environmental signals to adjust stomatal aperture. The size of the stomatal pore is regulated by movements of the guard cells driven by variations in their volume and turgor. As guard cells perceive and transduce a wide array of environmental cues, they provide an ideal system to elucidate early events of plant signaling. Reversible protein phosphorylation events are known to play a crucial role in the regulation of stomatal movements. However, in some cases, phosphorylation alone is not sufficient to achieve complete protein regulation, but is necessary to mediate the binding of interactors that modulate protein function. Among the phosphopeptide-binding proteins, the 14-3-3 proteins are the best characterized in plants. The 14-3-3s are found as multiple isoforms in eukaryotes and have been shown to be involved in the regulation of stomatal movements. In this review, we describe the current knowledge about 14-3-3 roles in the regulation of their binding partners in guard cells: receptors, ion pumps, channels, protein kinases, and some of their substrates. Regulation of these targets by 14-3-3 proteins is discussed and related to their function in guard cells during stomatal movements in response to abiotic or biotic stresses.
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Affiliation(s)
- Valérie Cotelle
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPS Castanet-Tolosan, France
| | - Nathalie Leonhardt
- UMR7265, Laboratoire de Biologie du Développement des Plantes, Service de Biologie Végétale et de Microbiologie Environnementales, Institut de Biologie Environnementale et Biotechnologie, CNRS-CEA-Université Aix-Marseille Saint-Paul-lez-Durance, France
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22
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K₂p channels in plants and animals. Pflugers Arch 2014; 467:1091-104. [PMID: 25369776 DOI: 10.1007/s00424-014-1638-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 10/18/2014] [Accepted: 10/21/2014] [Indexed: 10/24/2022]
Abstract
Two-pore domain potassium (K2P) channels are membrane proteins widely identified in mammals, plants, and other organisms. A functional channel is a dimer with each subunit comprising two pore-forming loops and four transmembrane domains. The genome of the model plant Arabidopsis thaliana harbors five genes coding for K2P channels. Homologs of Arabidopsis K2P channels have been found in all higher plants sequenced so far. As with the K2P channels in mammals, plant K2P channels are targets of external and internal stimuli, which fine-tune the electrical properties of the membrane for specialized transport and/or signaling tasks. Plant K2P channels are modulated by signaling molecules such as intracellular H(+) and calcium and physical factors like temperature and pressure. In this review, we ask the following: What are the similarities and differences between K2P channels in plants and animals in terms of their physiology? What is the nature of the last common ancestor (LCA) of these two groups of proteins? To answer these questions, we present physiological, structural, and phylogenetic evidence that discards the hypothesis proposing that the duplication and fusion that gave rise to the K2P channels occurred in a prokaryote LCA. Conversely, we argue that the K2P LCA was most likely a eukaryote organism. Consideration of plant and animal K2P channels in the same study is novel and likely to stimulate further exchange of ideas between students of these fields.
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23
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Kollist H, Nuhkat M, Roelfsema MRG. Closing gaps: linking elements that control stomatal movement. THE NEW PHYTOLOGIST 2014; 203:44-62. [PMID: 24800691 DOI: 10.1111/nph.12832] [Citation(s) in RCA: 186] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 03/27/2014] [Indexed: 05/18/2023]
Abstract
Stomata are an attractive experimental system in plant biology, because the responses of guard cells to environmental signals can be directly linked to changes in the aperture of stomatal pores. In this review, the mechanics of stomatal movement are discussed in relation to ion transport in guard cells. Emphasis is placed on the ion pumps, transporters, and channels in the plasma membrane, as well as in the vacuolar membrane. The biophysical properties of transport proteins for H(+), K(+), Ca(2+), and anions are discussed and related to their function in guard cells during stomatal movements. Guard cell signaling pathways for ABA, CO2, ozone, microbe-associated molecular patterns (MAMPs) and blue light are presented. Special attention is given to the regulation of the slow anion channel (SLAC) and SLAC homolog (SLAH)-type anion channels by the ABA signalosome. Over the last decade, several knowledge gaps in the regulation of ion transport in guard cells have been closed. The current state of knowledge is an excellent starting point for tackling important open questions concerning stress tolerance in plants.
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Affiliation(s)
- Hannes Kollist
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia
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24
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Hamamoto S, Uozumi N. Organelle-localized potassium transport systems in plants. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:743-7. [PMID: 24810770 DOI: 10.1016/j.jplph.2013.09.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 09/06/2013] [Accepted: 09/06/2013] [Indexed: 05/03/2023]
Abstract
Some intracellular organelles found in eukaryotes such as plants have arisen through the endocytotic engulfment of prokaryotic cells. This accounts for the presence of plant membrane intrinsic proteins that have homologs in prokaryotic cells. Other organelles, such as those of the endomembrane system, are thought to have evolved through infolding of the plasma membrane. Acquisition of intracellular components (organelles) in the cells supplied additional functions for survival in various natural environments. The organelles are surrounded by biological membranes, which contain membrane-embedded K(+) transport systems allowing K(+) to move across the membrane. K(+) transport systems in plant organelles act coordinately with the plasma membrane intrinsic K(+) transport systems to maintain cytosolic K(+) concentrations. Since it is sometimes difficult to perform direct studies of organellar membrane proteins in plant cells, heterologous expression in yeast and Escherichia coli has been used to elucidate the function of plant vacuole K(+) channels and other membrane transporters. The vacuole is the largest organelle in plant cells; it has an important task in the K(+) homeostasis of the cytoplasm. The initial electrophysiological measurements of K(+) transport have categorized three classes of plant vacuolar cation channels, and since then molecular cloning approaches have led to the isolation of genes for a number of K(+) transport systems. Plants contain chloroplasts, derived from photoautotrophic cyanobacteria. A novel K(+) transport system has been isolated from cyanobacteria, which may add to our understanding of K(+) flux across the thylakoid membrane and the inner membrane of the chloroplast. This chapter will provide an overview of recent findings regarding plant organellar K(+) transport proteins.
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Affiliation(s)
- Shin Hamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
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25
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Adams E, Shin R. Transport, signaling, and homeostasis of potassium and sodium in plants. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2014; 56:231-49. [PMID: 24393374 DOI: 10.1111/jipb.12159] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/31/2013] [Indexed: 05/17/2023]
Abstract
Potassium (K⁺) is an essential macronutrient in plants and a lack of K⁺ significantly reduces the potential for plant growth and development. By contrast, sodium (Na⁺), while beneficial to some extent, at high concentrations it disturbs and inhibits various physiological processes and plant growth. Due to their chemical similarities, some functions of K⁺ can be undertaken by Na⁺ but K⁺ homeostasis is severely affected by salt stress, on the other hand. Recent advances have highlighted the fascinating regulatory mechanisms of K⁺ and Na⁺ transport and signaling in plants. This review summarizes three major topics: (i) the transport mechanisms of K⁺ and Na⁺ from the soil to the shoot and to the cellular compartments; (ii) the mechanisms through which plants sense and respond to K⁺ and Na⁺ availability; and (iii) the components involved in maintenance of K⁺/Na⁺ homeostasis in plants under salt stress.
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Affiliation(s)
- Eri Adams
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan
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26
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Carraretto L, Formentin E, Teardo E, Checchetto V, Tomizioli M, Morosinotto T, Giacometti GM, Finazzi G, Szabó I. A Thylakoid-Located Two-Pore K+ Channel Controls Photosynthetic Light Utilization in Plants. Science 2013; 342:114-8. [DOI: 10.1126/science.1242113] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The size of the light-induced proton motive force (pmf) across the thylakoid membrane of chloroplasts is regulated in response to environmental stimuli. Here, we describe a component of the thylakoid membrane, the two-pore potassium (K+) channel TPK3, which modulates the composition of the pmf through ion counterbalancing. Recombinant TPK3 exhibited potassium-selective channel activity sensitive to Ca2+ and H+. In Arabidopsis plants, the channel is found in the thylakoid stromal lamellae. Arabidopsis plants silenced for the TPK3 gene display reduced growth and altered thylakoid membrane organization. This phenotype reflects an impaired capacity to generate a normal pmf, which results in reduced CO2 assimilation and deficient nonphotochemical dissipation of excess absorbed light. Thus, the TPK3 channel manages the pmf necessary to convert photochemical energy into physiological functions.
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27
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Isayenkov S, Maathuis FJM. Arabidopsis thaliana vacuolar TPK channels form functional K⁺ uptake pathways in Escherichia coli. PLANT SIGNALING & BEHAVIOR 2013; 8:e24665. [PMID: 23656881 PMCID: PMC3909031 DOI: 10.4161/psb.24665] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 04/11/2013] [Accepted: 04/11/2013] [Indexed: 05/20/2023]
Abstract
Very few vacuolar two pore potassium channels (TPKs) have been functionally characterized. In this paper we have used complementation of K(+) uptake deficient Escherichia coli mutant LB2003 to analyze the functional properties of Arabidopsis thaliana TPK family members. The four isoforms of AtTPKs were cloned and expressed in LB2003 E. coli background.The expression of channels in bacteria was analyzed by RT-PCR. Our results show that AtTPK1, AtTPK2 and AtTPK5 are restoring the LB2003 growth on low K(+) media. The analysis of potassium uptake exhibited elevated level of K(+) uptake in the same three types of AtTPKs transformants.
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Latz A, Mehlmer N, Zapf S, Mueller TD, Wurzinger B, Pfister B, Csaszar E, Hedrich R, Teige M, Becker D. Salt stress triggers phosphorylation of the Arabidopsis vacuolar K+ channel TPK1 by calcium-dependent protein kinases (CDPKs). MOLECULAR PLANT 2013; 6:1274-1289. [PMID: 23253603 PMCID: PMC3971370 DOI: 10.1093/mp/sss158] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
14-3-3 proteins play an important role in the regulation of many cellular processes. The Arabidopsis vacuolar two-pore K(+) channel 1 (TPK1) interacts with the 14-3-3 protein GRF6 (GF14-λ). Upon phosphorylation of the putative binding motif in the N-terminus of TPK1, GRF6 binds to TPK1 and activates the potassium channel. In order to gain a deeper understanding of this 14-3-3-mediated signal transduction, we set out to identify the respective kinases, which regulate the phosphorylation status of the 14-3-3 binding motif in TPK1. Here, we report that the calcium-dependent protein kinases (CDPKs) can phosphorylate and thereby activate the 14-3-3 binding motif in TPK1. Focusing on the stress-activated kinase CPK3, we visualized direct and specific interaction of TPK1 with the kinase at the tonoplast in vivo. In line with its proposed role in K(+) homeostasis, TPK1 phosphorylation was found to be induced by salt stress in planta, and both cpk3 and tpk1 mutants displayed salt-sensitive phenotypes. Molecular modeling of the TPK1-CPK3 interaction domain provided mechanistic insights into TPK1 stress-regulated phosphorylation responses and pinpointed two arginine residues in the N-terminal 14-3-3 binding motif in TPK1 critical for kinase interaction. Taken together, our studies provide evidence for an essential role of the vacuolar potassium channel TPK1 in salt-stress adaptation as a target of calcium-regulated stress signaling pathways involving Ca(2+), Ca(2+)-dependent kinases, and 14-3-3 proteins.
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Affiliation(s)
- Andreas Latz
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
| | - Norbert Mehlmer
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria
| | - Simone Zapf
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
| | - Thomas D. Mueller
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
| | - Bernhard Wurzinger
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria
| | - Barbara Pfister
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria
| | - Edina Csaszar
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria
| | - Rainer Hedrich
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
- College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Markus Teige
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria
| | - Dirk Becker
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
- To whom correspondence should be addressed. , tel. +49 (0)931/888-6108, fax +49 (0)931/888-6157
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Sharma T, Dreyer I, Riedelsberger J. The role of K(+) channels in uptake and redistribution of potassium in the model plant Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2013; 4:224. [PMID: 23818893 PMCID: PMC3694395 DOI: 10.3389/fpls.2013.00224] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/09/2013] [Indexed: 05/17/2023]
Abstract
Potassium (K(+)) is inevitable for plant growth and development. It plays a crucial role in the regulation of enzyme activities, in adjusting the electrical membrane potential and the cellular turgor, in regulating cellular homeostasis and in the stabilization of protein synthesis. Uptake of K(+) from the soil and its transport to growing organs is essential for a healthy plant development. Uptake and allocation of K(+) are performed by K(+) channels and transporters belonging to different protein families. In this review we summarize the knowledge on the versatile physiological roles of plant K(+) channels and their behavior under stress conditions in the model plant Arabidopsis thaliana.
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Affiliation(s)
- Tripti Sharma
- Molecular Biology, Institute for Biochemistry and Biology, University of PotsdamPotsdam, Germany
- IMPRS-PMPG, Max-Planck Institute of Molecular Plant PhysiologyPotsdam, Germany
| | - Ingo Dreyer
- Centro de Biotecnologia y Genomica de Plantas, Universidad Politécnica de MadridMadrid, Spain
- *Correspondence: Ingo Dreyer, Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, Pozuelo de Alarcón, Madrid E-28223, Spain e-mail:
| | - Janin Riedelsberger
- Molecular Biology, Institute for Biochemistry and Biology, University of PotsdamPotsdam, Germany
- IMPRS-PMPG, Max-Planck Institute of Molecular Plant PhysiologyPotsdam, Germany
- Janin Riedelsberger, Molecular Biology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24/25, House 20, D-14476 Potsdam, Germany e-mail:
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Abstract
Since the first recordings of single potassium channel activities in the plasma membrane of guard cells more than 25 years ago, patch-clamp studies discovered a variety of ion channels in all cell types and plant species under inspection. Their properties differed in a cell type- and cell membrane-dependent manner. Guard cells, for which the existence of plant potassium channels was initially documented, advanced to a versatile model system for studying plant ion channel structure, function, and physiology. Interestingly, one of the first identified potassium-channel genes encoding the Shaker-type channel KAT1 was shown to be highly expressed in guard cells. KAT1-type channels from Arabidopsis thaliana and its homologs from other species were found to encode the K+-selective inward rectifiers that had already been recorded in early patch-clamp studies with guard cells. Within the genome era, additional Arabidopsis Shaker-type channels appeared. All nine members of the Arabidopsis Shaker family are localized at the plasma membrane, where they either operate as inward rectifiers, outward rectifiers, weak voltage-dependent channels, or electrically silent, but modulatory subunits. The vacuole membrane, in contrast, harbors a set of two-pore K+ channels. Just very recently, two plant anion channel families of the SLAC/SLAH and ALMT/QUAC type were identified. SLAC1/SLAH3 and QUAC1 are expressed in guard cells and mediate Slow- and Rapid-type anion currents, respectively, that are involved in volume and turgor regulation. Anion channels in guard cells and other plant cells are key targets within often complex signaling networks. Here, the present knowledge is reviewed for the plant ion channel biology. Special emphasis is drawn to the molecular mechanisms of channel regulation, in the context of model systems and in the light of evolution.
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Affiliation(s)
- Rainer Hedrich
- University of Wuerzburg, Institute for Molecular Plant Physiology and Biophysics, Wuerzburg, Germany; and King Saud University, Riyadh, Saudi Arabia
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Isayenkov S, Isner JC, Maathuis FJM. Membrane localisation diversity of TPK channels and their physiological role. PLANT SIGNALING & BEHAVIOR 2011; 6:1201-4. [PMID: 21757998 PMCID: PMC3260722 DOI: 10.4161/psb.6.8.15808] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 04/12/2011] [Indexed: 05/23/2023]
Abstract
Potassium (K) is one of the major nutrients that is essential for plant growth and development. The majority of cellular K+ resides in the vacuole and tonoplast K+ channels of the TPK (Two Pore K) family are main players in cellular K+ homeostasis. All TPK channels were previously reported to be expressed in the tonoplast of the large central lytic vacuole (LV) except for one isoform in Arabidopsis that resides in the plasma membrane. However, plant cells often contain more than one type of vacuole that coexist in the same cell. We recently showed that two TPK isoforms (OsTPKa and OsTPKb) from Oryza sativa localise to different vacuoles with OsTPKa predominantly found in the LV tonoplast and OsTPKb primarily in smaller compartments that resemble small vacuoles (SVs). Our study further revealed that it is the C-terminal domain that determines differential targeting of OsTPKa and OsTPKb. Three C-terminal amino acids were particularly relevant for targeting TPKs to their respective endomembranes. In this addendum we further evaluate how the different localisation of TPKa and TPKb impact on their physiological role and how TPKs provide a potential tool to study the physiology of different types of vacuole.
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Affiliation(s)
- Stanislav Isayenkov
- Department of Genomics and Molecular Biotechnology, Institute of Food Biotechnology and Genomics, Kiev, Ukraine
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32
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Abstract
• Plant two-pore K(+) channels (TPKs) have been shown previously to play a role in vacuolar K(+) homeostasis. TPK activity is insensitive to membrane voltage, but regulated by cytoplasmic calcium and 14-3-3 proteins. This study reports that membrane stretch and osmotic gradients also alter the activity of TPKs from Arabidopsis, rice and barley, and that this may have a physiological relevance for osmotic homeostasis. • Mechanosensitivity was studied using patch clamp experiments and TPKs from Arabidopsis, rice and barley. In addition, the capability of TPKs to act as osmosensors was determined. By using protoplast disruption assays and intact plant survival assays, in genotypes that differed in TPK expression, the physiological relevance of TPK-based osmosensing was tested. • TPKs from all three species showed varying degrees of mechanosensitivity. TPK activity in channels from all three species was sensitive to trans-tonoplast osmotic gradients. TPK osmosensing is likely to proceed via the detection of small perturbations in membrane tension. Intact plant and protoplast assays showed that TPK-based osmosensing is important during exposure to rapid changes in external osmolarity. • Vacuolar TPK channels can act as intracellular osmosensors and rapidly increase channel activity during hypo-osmotic shock to release vacuolar K(+) .
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Isayenkov S, Isner JC, Maathuis FJ. Rice two-pore K+ channels are expressed in different types of vacuoles. THE PLANT CELL 2011; 23:756-68. [PMID: 21224427 PMCID: PMC3077780 DOI: 10.1105/tpc.110.081463] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 11/30/2010] [Accepted: 12/17/2010] [Indexed: 05/17/2023]
Abstract
Potassium (K+) is a major nutrient for plant growth and development. Vacuolar K+ ion channels of the two-pore K+ (TPK) family play an important role in maintaining K+ homeostasis. Several TPK channels were previously shown to be expressed in the lytic vacuole (LV) tonoplast. Plants also contain smaller protein storage vacuoles (PSVs) that contain membrane transporters. However, the mechanisms that define how membrane proteins reach different vacuolar destinations are largely unknown. The Oryza sativa genome encodes two TPK isoforms (TPKa and TPKb) that have very similar sequences and are ubiquitously expressed. The electrophysiological properties of both TPKs were comparable, showing inward rectification and voltage independence. In spite of high levels of similarity in sequence and transport properties, the cellular localization of TPKa and TPKb channels was different, with TPKa localization predominantly at the large LV and TPKb primarily in smaller PSV-type compartments. Trafficking of TPKa was sensitive to brefeldin A, while that of TPKb was not. The use of TPKa:TPKb chimeras showed that C-terminal domains are crucial for the differential targeting of TPKa and TPKb. Site-directed mutagenesis of C-terminal residues that were different between TPKa and TPKb identified three amino acids that are important in determining ultimate vacuolar destination.
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Affiliation(s)
| | | | - Frans J.M. Maathuis
- University of York, Biology Department/Area 9, York YO10 5DD, United Kingdom
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34
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Jossier M, Kroniewicz L, Dalmas F, Le Thiec D, Ephritikhine G, Thomine S, Barbier-Brygoo H, Vavasseur A, Filleur S, Leonhardt N. The Arabidopsis vacuolar anion transporter, AtCLCc, is involved in the regulation of stomatal movements and contributes to salt tolerance. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:563-76. [PMID: 20822503 DOI: 10.1111/j.1365-313x.2010.04352.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In plant cells, anion channels and transporters are essential for key functions such as nutrition, resistance to biotic or abiotic stresses, and ion homeostasis. In Arabidopsis, members of the chloride channel (CLC) family located in intracellular organelles have been shown to be required for nitrate homeostasis or pH adjustment, and previous results indicated that AtCLCc is involved in nitrate accumulation. We investigated new physiological functions of this CLC member in Arabidopsis. Here we report that AtCLCc is strongly expressed in guard cells and pollen and more weakly in roots. Use of an AtCLCc:GFP fusion revealed localization to the tonoplast. Disruption of the AtCLCc gene by a T-DNA insertion in four independent lines affected physiological responses that are directly related to the movement of chloride across the tonoplast membrane. Opening of clcc stomata was reduced in response to light, and ABA treatment failed to induce their closure, whereas application of KNO₃ but not KCl restored stomatal opening. clcc mutant plants were hypersensitive to NaCl treatment when grown on soil, and to NaCl and KCl in vitro, confirming the chloride dependence of the phenotype. These phenotypes were associated with modifications of chloride content in both guard cells and roots. These data demonstrate that AtCLCc is essential for stomatal movement and salt tolerance by regulating chloride homeostasis.
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Affiliation(s)
- Mathieu Jossier
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France
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36
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Voelker C, Gomez-Porras JL, Becker D, Hamamoto S, Uozumi N, Gambale F, Mueller-Roeber B, Czempinski K, Dreyer I. Roles of tandem-pore K+ channels in plants - a puzzle still to be solved. PLANT BIOLOGY (STUTTGART, GERMANY) 2010; 12 Suppl 1:56-63. [PMID: 20712621 DOI: 10.1111/j.1438-8677.2010.00353.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The group of voltage-independent K(+) channels in Arabidopsis thaliana consists of six members, five tandem-pore channels (TPK1-TPK5) and a single K(ir)-like channel (KCO3). All TPK/KCO channels are located at the vacuolar membrane except for TPK4, which was shown to be a plasma membrane channel in pollen. The vacuolar channels interact with 14-3-3 proteins (also called General Regulating Factors, GRFs), indicating regulation at the level of protein-protein interactions. Here we review current knowledge about these ion channels and their genes, and highlight open questions that need to be urgently addressed in future studies to fully appreciate the physiological functions of these ion channels.
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Affiliation(s)
- C Voelker
- Institute of Biochemistry and Biology, Molecular Biology, University of Potsdam, Potsdam-Golm, Germany.
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K+ transport characteristics of the plasma membrane tandem-pore channel TPK4 and pore chimeras with its vacuolar homologs. FEBS Lett 2010; 584:2433-9. [PMID: 20412800 DOI: 10.1016/j.febslet.2010.04.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2010] [Revised: 04/08/2010] [Accepted: 04/14/2010] [Indexed: 11/23/2022]
Abstract
Vacuolar tandem-pore channels could not be analysed in Xenopus oocytes so far, due to misguided translocation. Owing to the conservation of their pore regions, we were able to prepare functional pore-chimeras between the plasma membrane localised TPK4 and vacuolar TPKs. Thereby, we found evidence that TPK2, TPK3 and TPK5, just like TPK4, form potassium-selective channels with instantaneous current kinetics. Homology modelling and mutational analyses identified a pore-located aspartate residue (Asp110), which is involved in potassium permeation as well as in inward rectification of TPK4. Furthermore, dominant-negative mutations in the selectivity filter of either pore one or two (Asp86,Asp200) rendered TPK4 non-functional. This observation supports the notion that the functional TPK4 channel complex is formed by two subunits.
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38
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Kudla J, Batistic O, Hashimoto K. Calcium signals: the lead currency of plant information processing. THE PLANT CELL 2010; 22:541-63. [PMID: 20354197 PMCID: PMC2861448 DOI: 10.1105/tpc.109.072686] [Citation(s) in RCA: 634] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Ca(2+) signals are core transducers and regulators in many adaptation and developmental processes of plants. Ca(2+) signals are represented by stimulus-specific signatures that result from the concerted action of channels, pumps, and carriers that shape temporally and spatially defined Ca(2+) elevations. Cellular Ca(2+) signals are decoded and transmitted by a toolkit of Ca(2+) binding proteins that relay this information into downstream responses. Major transduction routes of Ca(2+) signaling involve Ca(2+)-regulated kinases mediating phosphorylation events that orchestrate downstream responses or comprise regulation of gene expression via Ca(2+)-regulated transcription factors and Ca(2+)-responsive promoter elements. Here, we review some of the remarkable progress that has been made in recent years, especially in identifying critical components functioning in Ca(2+) signal transduction, both at the single-cell and multicellular level. Despite impressive progress in our understanding of the processing of Ca(2+) signals during the past years, the elucidation of the exact mechanistic principles that underlie the specific recognition and conversion of the cellular Ca(2+) currency into defined changes in protein-protein interaction, protein phosphorylation, and gene expression and thereby establish the specificity in stimulus response coupling remain to be explored.
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Affiliation(s)
- Jörg Kudla
- Institut für Botanik, Universität Münster, 48149 Münster, Germany.
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39
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Assmann SM. Hope for Humpty Dumpty: systems biology of cellular signaling. PLANT PHYSIOLOGY 2010; 152:470-9. [PMID: 20032076 PMCID: PMC2815894 DOI: 10.1104/pp.109.151266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Affiliation(s)
- Sarah M Assmann
- Biology Department, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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41
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Kim TH, Böhmer M, Hu H, Nishimura N, Schroeder JI. Guard cell signal transduction network: advances in understanding abscisic acid, CO2, and Ca2+ signaling. ANNUAL REVIEW OF PLANT BIOLOGY 2010; 61:561-91. [PMID: 20192751 PMCID: PMC3056615 DOI: 10.1146/annurev-arplant-042809-112226] [Citation(s) in RCA: 811] [Impact Index Per Article: 57.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Stomatal pores are formed by pairs of specialized epidermal guard cells and serve as major gateways for both CO(2) influx into plants from the atmosphere and transpirational water loss of plants. Because they regulate stomatal pore apertures via integration of both endogenous hormonal stimuli and environmental signals, guard cells have been highly developed as a model system to dissect the dynamics and mechanisms of plant-cell signaling. The stress hormone ABA and elevated levels of CO(2) activate complex signaling pathways in guard cells that are mediated by kinases/phosphatases, secondary messengers, and ion channel regulation. Recent research in guard cells has led to a new hypothesis for how plants achieve specificity in intracellular calcium signaling: CO(2) and ABA enhance (prime) the calcium sensitivity of downstream calcium-signaling mechanisms. Recent progress in identification of early stomatal signaling components are reviewed here, including ABA receptors and CO(2)-binding response proteins, as well as systems approaches that advance our understanding of guard cell-signaling mechanisms.
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Affiliation(s)
| | | | - Honghong Hu
- University of California, San Diego, Division of Biological Sciences, Section of Cell and Developmental Biology, La Jolla, California 92093-0116
| | - Noriyuki Nishimura
- University of California, San Diego, Division of Biological Sciences, Section of Cell and Developmental Biology, La Jolla, California 92093-0116
| | - Julian I. Schroeder
- University of California, San Diego, Division of Biological Sciences, Section of Cell and Developmental Biology, La Jolla, California 92093-0116
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42
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White PJ, Wiesel L, Broadley MR. Cation Channels and the Uptake of Radiocaesium by Plants. ION CHANNELS AND PLANT STRESS RESPONSES 2010. [DOI: 10.1007/978-3-642-10494-7_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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43
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Szczerba MW, Britto DT, Kronzucker HJ. K+ transport in plants: physiology and molecular biology. JOURNAL OF PLANT PHYSIOLOGY 2009; 166:447-66. [PMID: 19217185 DOI: 10.1016/j.jplph.2008.12.009] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 11/10/2008] [Accepted: 12/10/2008] [Indexed: 05/06/2023]
Abstract
Potassium (K(+)) is an essential nutrient and the most abundant cation in plant cells. Plants have a wide variety of transport systems for K(+) acquisition, catalyzing K(+) uptake across a wide spectrum of external concentrations, and mediating K(+) movement within the plant as well as its efflux into the environment. K(+) transport responds to variations in external K(+) supply, to the presence of other ions in the root environment, and to a range of plant stresses, via Ca(2+) signaling cascades and regulatory proteins. This review will summarize the molecular identities of known K(+) transporters, and examine how this information supports physiological investigations of K(+) transport and studies of plant stress responses in a changing environment.
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Affiliation(s)
- Mark W Szczerba
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave., Davis, CA 95616, USA.
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44
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Abstract
Distinct potassium, anion, and calcium channels in the plasma membrane and vacuolar membrane of plant cells have been identified and characterized by patch clamping. Primarily owing to advances in Arabidopsis genetics and genomics, and yeast functional complementation, many of the corresponding genes have been identified. Recent advances in our understanding of ion channel genes that mediate signal transduction and ion transport are discussed here. Some plant ion channels, for example, ALMT and SLAC anion channel subunits, are unique. The majority of plant ion channel families exhibit homology to animal genes; such families include both hyperpolarization- and depolarization-activated Shaker-type potassium channels, CLC chloride transporters/channels, cyclic nucleotide-gated channels, and ionotropic glutamate receptor homologs. These plant ion channels offer unique opportunities to analyze the structural mechanisms and functions of ion channels. Here we review gene families of selected plant ion channel classes and discuss unique structure-function aspects and their physiological roles in plant cell signaling and transport.
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Affiliation(s)
- John M. Ward
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108;
| | - Pascal Mäser
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
| | - Julian I. Schroeder
- Division of Biological Sciences, Cell and Developmental Biology Section, University of California, San Diego, La Jolla, California 92093;
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45
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Sano T, Kutsuna N, Becker D, Hedrich R, Hasezawa S. Outward-rectifying K+ channel activities regulate cell elongation and cell division of tobacco BY-2 cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:55-64. [PMID: 18778403 DOI: 10.1111/j.1365-313x.2008.03672.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Potassium ions (K+) are required for plant growth and development, including cell division and cell elongation/expansion, which are mediated by the K+ transport system. In this study, we investigated the role of K+ in cell division using tobacco BY-2 protoplast cultures. Gene expression analysis revealed induction of the Shaker-like outward K+ channel gene, NTORK1, under cell-division conditions, whereas the inward K+ channel genes NKT1 and NtKC1 were induced under both cell-elongation and cell-division conditions. Repression of NTORK1 gene expression by expression of its antisense construct repressed cell division but accelerated cell elongation even under conditions promoting cell division. A decrease in the K+ content of cells and cellular osmotic pressure in dividing cells suggested that an increase in cell osmotic pressure by K+ uptake is not required for cell division. In contrast, K+ depletion, which reduced cell-division activity, decreased cytoplasmic pH as monitored using a fluorescent pH indicator, SNARF-1. Application of K+ or the cytoplasmic alkalizing reagent (NH(4))(2)SO(4) increased cytoplasmic pH and suppressed the reduction in cell-division activity. These results suggest that the K+ taken up into cells is used to regulate cytoplasmic pH during cell division.
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Affiliation(s)
- Toshio Sano
- Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
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46
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Kwak JM, Mäser P, Schroeder JI. The Clickable Guard Cell, Version II: Interactive Model of Guard Cell Signal Transduction Mechanisms and Pathways. THE ARABIDOPSIS BOOK 2008; 6:e0114. [PMID: 22303239 PMCID: PMC3243356 DOI: 10.1199/tab.0114] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Guard cells are located in the leaf epidermis and pairs of guard cells surround and form stomatal pores, which regulate CO(2) influx from the atmosphere into leaves for photosynthetic carbon fixation. Stomatal guard cells also regulate water loss of plants via transpiration to the atmosphere. Signal transduction mechanisms in guard cells integrate a multitude of different stimuli to modulate stomatal apertures. Stomata open in response to light. Stomata close in response to drought stress, elevated CO(2), ozone and low humidity. In response to drought, plants synthesize the hormone abscisic acid (ABA) that triggers closing of stomatal pores. Guard cells have become a highly developed model system for dissecting signal transduction mechanisms in plants and for elucidating how individual signaling mechanisms can interact within a network in a single cell. Many new findings have been made in the last few years. This chapter is an update of an electronic interactive chapter in the previous edition of The Arabidopsis Book (Mäser et al. 2003). Here we focus on mechanisms for which genes and mutations have been characterized, including signaling components for which there is substantial signaling, biochemical and genetic evidence. Ion channels have been shown to represent targets of early signal transduction mechanisms and provide functional signaling and quantitative analysis points to determine where and how mutations affect branches within the guard cell signaling network. Although a substantial number of genes and proteins that function in guard cell signaling have been identified in recent years, there are many more left to be identified and the protein-protein interactions within this network will be an important subject of future research. A fully interactive clickable electronic version of this publication can be accessed at the following web site: http://www-biology.ucsd.edu/labs/schroeder/clickablegc2/. The interactive clickable version includes the following features: Figure 1. Model for the roles of ion channels in ABA signaling.Figure 2. Blue light signaling pathways in guard cells.Figure 3. ABA signaling pathways in guard cells.Figure 1 is linked to explanations that appear upon mouse-over. Figure 2 and Figure 3 are clickable and linked to info boxes, which in turn are linked to TAIR, to relevant abstracts in PubMed, and to updated background explanations from Schroeder et al (2001), used with permission of Annual Reviews of Plant Biology.
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Affiliation(s)
- June M. Kwak
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
| | - Pascal Mäser
- Institute of Cell Biology, University of Berne, CH-3012 Bern, Switzerland
| | - Julian I. Schroeder
- Division of Biological Sciences, Cell and Developmental Biology Section and Center for Molecular Genetics, University of California, San Diego, La Jolla, California 92093-0116
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Dunkel M, Latz A, Schumacher K, Müller T, Becker D, Hedrich R. Targeting of vacuolar membrane localized members of the TPK channel family. MOLECULAR PLANT 2008; 1:938-49. [PMID: 19825594 DOI: 10.1093/mp/ssn064] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Four members of the tandem-pore potassium channel family of Arabidopsis thaliana (TPK1, 2, 3, and 5) reside in the vacuolar membrane, whereas TPK4 is a plasma membrane K(+)-channel. By constructing chimeras between TPK1 and TPK4, we attempted to identify channel domains involved in the trafficking process and found that the TPK1 cytoplasmic C-terminal domain (CT) is critical for the ER- as well as Golgi-sorting steps. Following site-directed mutagenesis, we identified a diacidic motif (DLE) required for ER-export of TPK1. However, this diacidic motif in the C-terminus is not conserved among other members of the TPK family, and TPK3 sorting is independent of its CT. Moreover, the 14-3-3 binding site of TPK1, essential for channel activation, is not involved in channel sorting.
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Affiliation(s)
- Marcel Dunkel
- University of Würzburg, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany
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Hamamoto S, Yabe I, Uozumi N. Electrophysiological properties of NtTPK1 expressed in yeast tonoplast. Biosci Biotechnol Biochem 2008; 72:2785-7. [PMID: 18838784 DOI: 10.1271/bbb.80354] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The patch clamp technique using enlarged yeast tonoplasts is an effective approach to characterizing the Nicotiana tabacum plant tonoplast K+ channel, NtTPK1. We report here that the NtTPK1-mediated currents comprise two phase components, both which were found to be highly selective for K+ over Na+ and Cl-.
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Affiliation(s)
- Shin Hamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
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Hamamoto S, Marui J, Matsuoka K, Higashi K, Igarashi K, Nakagawa T, Kuroda T, Mori Y, Murata Y, Nakanishi Y, Maeshima M, Yabe I, Uozumi N. Characterization of a tobacco TPK-type K+ channel as a novel tonoplast K+ channel using yeast tonoplasts. J Biol Chem 2008; 283:1911-20. [PMID: 18029350 DOI: 10.1074/jbc.m708213200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
The tonoplast K(+) membrane transport system plays a crucial role in maintaining K(+) homeostasis in plant cells. Here, we isolated cDNAs encoding a two-pore K(+) channel (NtTPK1) from Nicotiana tabacum cv. SR1 and cultured BY-2 tobacco cells. Two of the four variants of NtTPK1 contained VHG and GHG instead of the GYG signature sequence in the second pore region. All four products were functional when expressed in the Escherichia coli cell membrane, and NtTPK1 was targeted to the tonoplast in tobacco cells. Two of the three promoter sequences isolated from N. tabacum cv. SR1 were active, and expression from these was increased approximately 2-fold by salt stress or high osmotic shock. To determine the properties of NtTPK1, we enlarged mutant yeast cells with inactivated endogenous tonoplast channels and prepared tonoplasts suitable for patch clamp recording allowing the NtTPK1-related channel conductance to be distinguished from the small endogenous currents. NtTPK1 exhibited strong selectivity for K(+) over Na(+). NtTPK1 activity was sensitive to spermidine and spermine, which were shown to be present in tobacco cells. NtTPK1 was active in the absence of Ca(2+), but a cytosolic concentration of 45 microM Ca(2+) resulted in a 2-fold increase in the amplitude of the K(+) current. Acidification of the cytosol to pH 5.5 also markedly increased NtTPK1-mediated K(+) currents. These results show that NtTPK1 is a novel tonoplast K(+) channel belonging to a different group from the previously characterized vacuolar channels SV, FV, and VK.
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Affiliation(s)
- Shin Hamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
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Kung C, Zhou XL, Su ZW, Haynes WJ, Loukin SH, Saimi Y. Microbial Senses and Ion Channels. SENSING WITH ION CHANNELS 2008. [DOI: 10.1007/978-3-540-72739-2_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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