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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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Jin S, Wei M, Wei Y, Jiang Z. Insights into Plant Sensory Mechanisms under Abiotic Stresses. PLANTS (BASEL, SWITZERLAND) 2024; 13:1907. [PMID: 39065434 PMCID: PMC11280238 DOI: 10.3390/plants13141907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 07/08/2024] [Accepted: 07/08/2024] [Indexed: 07/28/2024]
Abstract
As sessile organisms, plants cannot survive in harmful environments, such as those characterized by drought, flood, heat, cold, nutrient deficiency, and salt or toxic metal stress. These stressors impair plant growth and development, leading to decreased crop productivity. To induce an appropriate response to abiotic stresses, plants must sense the pertinent stressor at an early stage to initiate precise signal transduction. Here, we provide an overview of recent progress in our understanding of the molecular mechanisms underlying plant abiotic stress sensing. Numerous biomolecules have been found to participate in the process of abiotic stress sensing and function as abiotic stress sensors in plants. Based on their molecular structure, these biomolecules can be divided into four groups: Ca2+-permeable channels, receptor-like kinases (RLKs), sphingolipids, and other proteins. This improved knowledge can be used to identify key molecular targets for engineering stress-resilient crops in the field.
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Affiliation(s)
- Songsong Jin
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; (S.J.); (M.W.); (Y.W.)
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Mengting Wei
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; (S.J.); (M.W.); (Y.W.)
| | - Yunmin Wei
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; (S.J.); (M.W.); (Y.W.)
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Zhonghao Jiang
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; (S.J.); (M.W.); (Y.W.)
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Kaur A, Madhu, Sharma A, Singh K, Upadhyay SK. Investigation of two-pore K + (TPK) channels in Triticum aestivum L. suggests their role in stress response. Heliyon 2024; 10:e27814. [PMID: 38533012 PMCID: PMC10963239 DOI: 10.1016/j.heliyon.2024.e27814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 02/28/2024] [Accepted: 03/07/2024] [Indexed: 03/28/2024] Open
Abstract
Two-pore K+ (TPK) channels are voltage-independent and involved in stress response in plants. Herein, we identified 12 TaTPK genes located on nine chromosomes in the Triticum aestivum genome. The majority of TaTPK genes comprised two exons. Each TaTPK channel comprised four transmembrane (TM) helices, N- and C-terminal ion-channel domains, two EF-hand domains and one 14-3-3 binding site. Additionally, highly conserved 'GYGD' motif responsible for K+ ion specificity, was found in between the TMs in both the ion-channel domains. Nine TaTPK channels were predicted to be localised at the plasma membrane, while three were vacuolar. The protein-protein and protein-chemical interactions indicated the coordinated functioning of the TaTPK channels with the other K+ transporters and their possible interaction with the Ca2+-signaling pathway. Expression studies suggested their importance in both vegetative and reproductive tissues development. Significantly modulated expression of various TaTPK genes during heat, drought, combined heat and drought and salt stresses, and after fungal infestation, depicted their function in stress responses. The miRNAs and transcription factors interaction analyses suggested their role in the hormone, light, growth and development-related, and stress-responsive signaling cascades. The current study suggested vital functions of various TaTPK genes, especially in stress response, and would provide an opportunity for their detailed characterization in future studies.
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Affiliation(s)
- Amandeep Kaur
- Department of Botany, Panjab University, Chandigarh, India, 160014
| | - Madhu
- Department of Botany, Panjab University, Chandigarh, India, 160014
| | - Alok Sharma
- Department of Botany, Panjab University, Chandigarh, India, 160014
- Regional Ayurveda Research Institute, Gwalior, Madhya Pradesh, 474001, India
| | - Kashmir Singh
- Department of Biotechnology, Panjab University, Chandigarh, India
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Lindberg S, Premkumar A. Ion Changes and Signaling under Salt Stress in Wheat and Other Important Crops. PLANTS (BASEL, SWITZERLAND) 2023; 13:46. [PMID: 38202354 PMCID: PMC10780558 DOI: 10.3390/plants13010046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/14/2023] [Accepted: 12/16/2023] [Indexed: 01/12/2024]
Abstract
High concentrations of sodium (Na+), chloride (Cl-), calcium (Ca2+), and sulphate (SO42-) are frequently found in saline soils. Crop plants cannot successfully develop and produce because salt stress impairs the uptake of Ca2+, potassium (K+), and water into plant cells. Different intracellular and extracellular ionic concentrations change with salinity, including those of Ca2+, K+, and protons. These cations serve as stress signaling molecules in addition to being essential for ionic homeostasis and nutrition. Maintaining an appropriate K+:Na+ ratio is one crucial plant mechanism for salt tolerance, which is a complicated trait. Another important mechanism is the ability for fast extrusion of Na+ from the cytosol. Ca2+ is established as a ubiquitous secondary messenger, which transmits various stress signals into metabolic alterations that cause adaptive responses. When plants are under stress, the cytosolic-free Ca2+ concentration can rise to 10 times or more from its resting level of 50-100 nanomolar. Reactive oxygen species (ROS) are linked to the Ca2+ alterations and are produced by stress. Depending on the type, frequency, and intensity of the stress, the cytosolic Ca2+ signals oscillate, are transient, or persist for a longer period and exhibit specific "signatures". Both the influx and efflux of Ca2+ affect the length and amplitude of the signal. According to several reports, under stress Ca2+ alterations can occur not only in the cytoplasm of the cell but also in the cell walls, nucleus, and other cell organelles and the Ca2+ waves propagate through the whole plant. Here, we will focus on how wheat and other important crops absorb Na+, K+, and Cl- when plants are under salt stress, as well as how Ca2+, K+, and pH cause intracellular signaling and homeostasis. Similar mechanisms in the model plant Arabidopsis will also be considered. Knowledge of these processes is important for understanding how plants react to salinity stress and for the development of tolerant crops.
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Affiliation(s)
- Sylvia Lindberg
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-114 18 Stockholm, Sweden
| | - Albert Premkumar
- Bharathiyar Group of Institutes, Guduvanchery 603202, Tamilnadu, India;
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Ali S, Tyagi A, Park S, Bae H. Understanding the mechanobiology of phytoacoustics through molecular Lens: Mechanisms and future perspectives. J Adv Res 2023:S2090-1232(23)00398-3. [PMID: 38101748 DOI: 10.1016/j.jare.2023.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 12/17/2023] Open
Abstract
BACKGROUND How plants emit, perceive, and respond to sound vibrations (SVs) is a long-standing question in the field of plant sensory biology. In recent years, there have been numerous studies on how SVs affect plant morphological, physiological, and biochemical traits related to growth and adaptive responses. For instance, under drought SVs navigate plant roots towards water, activate their defence responses against stressors, and increase nectar sugar in response to pollinator SVs. Also, plants emit SVs during stresses which are informative in terms of ecological and adaptive perspective. However, the molecular mechanisms underlying the SV perception and emission in plants remain largely unknown. Therefore, deciphering the complexity of plant-SV interactions and identifying bonafide receptors and signaling players will be game changers overcoming the roadblocks in phytoacoustics. AIM OF REVIEW The aim of this review is to provide an overview of recent developments in phytoacoustics. We primarily focuss on SV signal perception and transduction with current challenges and future perspectives. KEY SCIENTIFIC CONCEPTS OF REVIEW Timeline breakthroughs in phytoacoustics have constantly shaped our understanding and belief that plants may emit and respond to SVs like other species. However, unlike other plant mechanostimuli, little is known about SV perception and signal transduction. Here, we provide an update on phytoacoustics and its ecological importance. Next, we discuss the role of cell wall receptor-like kinases, mechanosensitive channels, intracellular organelle signaling, and other key players involved in plant-SV receptive pathways that connect them. We also highlight the role of calcium (Ca2+), reactive oxygen species (ROS), hormones, and other emerging signaling molecules in SV signal transduction. Further, we discuss the importance of molecular, biophysical, computational, and live cell imaging tools for decoding the molecular complexity of acoustic signaling in plants. Finally, we summarised the role of SV priming in plants and discuss how SVs could modulate plant defense and growth trade-offs during other stresses.
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Affiliation(s)
- Sajad Ali
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk 38541, Republic of Korea
| | - Anshika Tyagi
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk 38541, Republic of Korea
| | - Suvin Park
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk 38541, Republic of Korea
| | - Hanhong Bae
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk 38541, Republic of Korea.
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Wang H, Ye L, Zhou L, Yu J, Pang B, Zuo D, Gu L, Zhu B, Du X, Wang H. Co-Expression Network Analysis of the Transcriptome Identified Hub Genes and Pathways Responding to Saline-Alkaline Stress in Sorghum bicolor L. Int J Mol Sci 2023; 24:16831. [PMID: 38069156 PMCID: PMC10706439 DOI: 10.3390/ijms242316831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/20/2023] [Accepted: 11/24/2023] [Indexed: 12/18/2023] Open
Abstract
Soil salinization, an intractable problem, is becoming increasingly serious and threatening fragile natural ecosystems and even the security of human food supplies. Sorghum (Sorghum bicolor L.) is one of the main crops growing in salinized soil. However, the tolerance mechanisms of sorghum to saline-alkaline soil are still ambiguous. In this study, RNA sequencing was carried out to explore the gene expression profiles of sorghum treated with sodium bicarbonate (150 mM, pH = 8.0, treated for 0, 6, 12 and 24 h). The results show that 6045, 5122, 6804, 7978, 8080 and 12,899 differentially expressed genes (DEGs) were detected in shoots and roots after 6, 12 and 24 h treatments, respectively. GO, KEGG and weighted gene co-expression analyses indicate that the DEGs generated by saline-alkaline stress were primarily enriched in plant hormone signal transduction, the MAPK signaling pathway, starch and sucrose metabolism, glutathione metabolism and phenylpropanoid biosynthesis. Key pathway and hub genes (TPP1, WRKY61, YSL1 and NHX7) are mainly related to intracellular ion transport and lignin synthesis. The molecular and physiological regulation processes of saline-alkali-tolerant sorghum are shown by these results, which also provide useful knowledge for improving sorghum yield and quality under saline-alkaline conditions.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Xuye Du
- School of Life Sciences, Guizhou Normal University, Guiyang 550025, China; (H.W.); (L.Y.); (L.Z.); (J.Y.); (B.P.); (D.Z.); (L.G.); (B.Z.)
| | - Huinan Wang
- School of Life Sciences, Guizhou Normal University, Guiyang 550025, China; (H.W.); (L.Y.); (L.Z.); (J.Y.); (B.P.); (D.Z.); (L.G.); (B.Z.)
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Tyagi A, Ali S, Park S, Bae H. Deciphering the role of mechanosensitive channels in plant root biology: perception, signaling, and adaptive responses. PLANTA 2023; 258:105. [PMID: 37878056 DOI: 10.1007/s00425-023-04261-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 10/02/2023] [Indexed: 10/26/2023]
Abstract
MAIN CONCLUSION Mechanosensitive channels are integral membrane proteins that rapidly translate extrinsic or intrinsic mechanical tensions into biological responses. They can serve as potential candidates for developing smart-resilient crops with efficient root systems. Mechanosensitive (MS) calcium channels are molecular switches for mechanoperception and signal transduction in all living organisms. Although tremendous progress has been made in understanding mechanoperception and signal transduction in bacteria and animals, this remains largely unknown in plants. However, identification and validation of MS channels such as Mid1-complementing activity channels (MCAs), mechanosensitive-like channels (MSLs), and Piezo channels (PIEZO) has been the most significant discovery in plant mechanobiology, providing novel insights into plant mechanoperception. This review summarizes recent advances in root mechanobiology, focusing on MS channels and their related signaling players, such as calcium ions (Ca2+), reactive oxygen species (ROS), and phytohormones. Despite significant advances in understanding the role of Ca2+ signaling in root biology, little is known about the involvement of MS channel-driven Ca2+ and ROS signaling. Additionally, the hotspots connecting the upstream and downstream signaling of MS channels remain unclear. In light of this, we discuss the present knowledge of MS channels in root biology and their role in root developmental and adaptive traits. We also provide a model highlighting upstream (cell wall sensors) and downstream signaling players, viz., Ca2+, ROS, and hormones, connected with MS channels. Furthermore, we highlighted the importance of emerging signaling molecules, such as nitric oxide (NO), hydrogen sulfide (H2S), and neurotransmitters (NTs), and their association with root mechanoperception. Finally, we conclude with future directions and knowledge gaps that warrant further research to decipher the complexity of root mechanosensing.
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Affiliation(s)
- Anshika Tyagi
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk, 38541, Republic of Korea.
| | - Sajad Ali
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk, 38541, Republic of Korea
| | - Suvin Park
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk, 38541, Republic of Korea
| | - Hanhong Bae
- Department of Biotechnology, Yeungnam University, Gyeongsan Gyeongbuk, 38541, Republic of Korea.
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Zhang J, Maksaev G, Yuan P. Open structure and gating of the Arabidopsis mechanosensitive ion channel MSL10. Nat Commun 2023; 14:6284. [PMID: 37805510 PMCID: PMC10560256 DOI: 10.1038/s41467-023-42117-5] [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: 07/25/2023] [Accepted: 09/29/2023] [Indexed: 10/09/2023] Open
Abstract
Plants are challenged by drastically different osmotic environments during growth and development. Adaptation to these environments often involves mechanosensitive ion channels that can detect and respond to mechanical force. In the model plant Arabidopsis thaliana, the mechanosensitive channel MSL10 plays a crucial role in hypo-osmotic shock adaptation and programmed cell death induction, but the molecular basis of channel function remains poorly understood. Here, we report a structural and electrophysiological analysis of MSL10. The cryo-electron microscopy structures reveal a distinct heptameric channel assembly. Structures of the wild-type channel in detergent and lipid environments, and in the absence of membrane tension, capture an open conformation. Furthermore, structural analysis of a non-conductive mutant channel demonstrates that reorientation of phenylalanine side chains alone, without main chain rearrangements, may generate the hydrophobic gate. Together, these results reveal a distinct gating mechanism and advance our understanding of mechanotransduction.
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Affiliation(s)
- Jingying Zhang
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Grigory Maksaev
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
| | - Peng Yuan
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA.
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA.
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Haque US, Elias SM, Jahan I, Seraj ZI. Functional genomic analysis of K + related salt-responsive transporters in tolerant and sensitive genotypes of rice. FRONTIERS IN PLANT SCIENCE 2023; 13:1089109. [PMID: 36743539 PMCID: PMC9893783 DOI: 10.3389/fpls.2022.1089109] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/19/2022] [Indexed: 06/18/2023]
Abstract
INTRODUCTION Salinity is a complex environmental stress that affects the growth and production of rice worldwide. But there are some rice landraces in coastal regions that can survive in presence of highly saline conditions. An understanding of the molecular attributes contributing to the salinity tolerance of these genotypes is important for developing salt-tolerant high yielding modern genotypes to ensure food security. Therefore, we investigated the role and functional differences of two K+ salt-responsive transporters. These are OsTPKa or Vacuolar two-pore potassium channel and OsHAK_like or a hypothetical protein of the HAK family. These transporters were selected from previously identified QTLs from the tolerant rice landrace genotype (Horkuch) and sensitive genotype (IR29). METHODS In silico comparative sequence analysis of the promoter sequences of two these genes between Horkuch and IR29 was done. Real-Time expression of the selected genes in leaves and roots of IR29 (salt-sensitive), I-14 and I-71 (Recombinant Inbred Lines of IR29(♀)× Horkuch), Horkuch and Pokkali (salt-tolerant) under salt-stress at different time points was analyzed. For further insight, OsTPKa and OsHAK_like were chosen for loss-of-function genomic analysis in Horkuch using the CRISPR/Cas9 tool. Furthermore, OsTPKa was chosen for cloning into a sensitive variety by Gateway technology to observe the effect of gain-of-function. RESULTS The promoter sequences of the OsTPKa and OsHAK_like genes showed some significant differences in promoter sequences which may give a survival advantage to Horkuch under salt-stress. These two genes were also found to be overexpressed in tolerant varieties (Horkuch and Pokkali). Moreover, a coordinated expression pattern between these two genes was observed in tolerant Horkuch under salt-stress. Independently transformed plants where the expression of these genes was significantly lowered, performed poorly in physiological tests for salinity tolerance. On the other hand, positively transformed T0 plants with the OsTPKa gene from Horkuch consistently showed growth advantage under both control and salt stress. DISCUSSION The poor performance of the transgenic plants with the down-regulated genes OsTPKa and OsHAK_like under salt stress supports the assumption that OsTPKa and OsHAK_like play important roles in defending the rice landrace Horkuch against salt stress, minimizing salt injury, and maintaining plant growth. Moreover, the growth advantage provided by overexpression of the vacuolar OsTPKa K+ transporter, particularly under salt stress reconfirms its important role in providing salt tolerance. The QTL locus from Horkuch containing these two transporters maybe bred into commercial rice to produce high-yielding salt tolerant rice.
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Affiliation(s)
- Umme Sabrina Haque
- Plant Biotechnology Laboratory, Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, Bangladesh
| | - Sabrina M. Elias
- Department of Life Sciences, Independent University Bangladesh, Dhaka, Bangladesh
| | - Israt Jahan
- Plant Biotechnology Laboratory, Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, Bangladesh
| | - Zeba I. Seraj
- Plant Biotechnology Laboratory, Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, Bangladesh
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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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Sukharev S, Anishkin A. Mechanosensitive Channels: History, Diversity, and Mechanisms. BIOCHEMISTRY (MOSCOW), SUPPLEMENT SERIES A: MEMBRANE AND CELL BIOLOGY 2022. [DOI: 10.1134/s1990747822090021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Guichard M, Thomine S, Frachisse JM. Mechanotransduction in the spotlight of mechano-sensitive channels. CURRENT OPINION IN PLANT BIOLOGY 2022; 68:102252. [PMID: 35772372 DOI: 10.1016/j.pbi.2022.102252] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 05/06/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
The study of mechanosensitive channels (MS) in living organisms has progressed considerably over the past two decades. The understanding of their roles in mechanosensation and mechanotransduction was consecrated by the awarding of the Nobel Prize in 2021 to A. Patapoutian for his discoveries on the role of MS channels in mechanoperception in humans. In this review, we first summarize the fundamental properties of MS channels and their mode of operation. Then in a second step, we provide an update on the knowledge on the families of MS channels identified in plants and the roles and functions that have been attributed to them.
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Affiliation(s)
- Marjorie Guichard
- Institute of Cell and Interaction Biology, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Sébastien Thomine
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Jean-Marie Frachisse
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
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Entanglement of Arabidopsis Seedlings to a Mesh Substrate under Microgravity Conditions in KIBO on the ISS. PLANTS 2022; 11:plants11070956. [PMID: 35406935 PMCID: PMC9003378 DOI: 10.3390/plants11070956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/27/2022] [Accepted: 03/29/2022] [Indexed: 11/17/2022]
Abstract
The International Space Station (ISS) provides a precious opportunity to study plant growth and development under microgravity (micro-G) conditions. In this study, four lines of Arabidopsis seeds (wild type, wild-type MCA1-GFP, mca1-knockout, and MCA1-overexpressed) were cultured on a nylon lace mesh placed on Gelrite-solidified MS-medium in the Japanese experiment module KIBO on the ISS, and the entanglement of roots with the mesh was examined under micro-G and 1-G conditions. We found that root entanglement with the mesh was enhanced, and root coiling was induced under the micro-G condition. This behavior was less pronounced in mca1-knockout seedlings, although MCA1-GFP distribution at the root tip of the seedlings was nearly the same in micro-G-grown seedlings and the ground control seedlings. Possible involvement of MCA1 in the root entanglement is discussed.
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Codjoe JM, Miller K, Haswell ES. Plant cell mechanobiology: Greater than the sum of its parts. THE PLANT CELL 2022; 34:129-145. [PMID: 34524447 PMCID: PMC8773992 DOI: 10.1093/plcell/koab230] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 09/09/2021] [Indexed: 05/04/2023]
Abstract
The ability to sense and respond to physical forces is critical for the proper function of cells, tissues, and organisms across the evolutionary tree. Plants sense gravity, osmotic conditions, pathogen invasion, wind, and the presence of barriers in the soil, and dynamically integrate internal and external stimuli during every stage of growth and development. While the field of plant mechanobiology is growing, much is still poorly understood-including the interplay between mechanical and biochemical information at the single-cell level. In this review, we provide an overview of the mechanical properties of three main components of the plant cell and the mechanoperceptive pathways that link them, with an emphasis on areas of complexity and interaction. We discuss the concept of mechanical homeostasis, or "mechanostasis," and examine the ways in which cellular structures and pathways serve to maintain it. We argue that viewing mechanics and mechanotransduction as emergent properties of the plant cell can be a useful conceptual framework for synthesizing current knowledge and driving future research.
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Affiliation(s)
- Jennette M Codjoe
- Department of Biology and Center for Engineering Mechanobiology, Washington University in St Louis, St Louis, Missouri, 63130, USA
| | - Kari Miller
- Department of Biology and Center for Engineering Mechanobiology, Washington University in St Louis, St Louis, Missouri, 63130, USA
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15
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Xu T, Niu J, Jiang Z. Sensing Mechanisms: Calcium Signaling Mediated Abiotic Stress in Plants. FRONTIERS IN PLANT SCIENCE 2022; 13:925863. [PMID: 35769297 PMCID: PMC9234572 DOI: 10.3389/fpls.2022.925863] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 05/25/2022] [Indexed: 05/12/2023]
Abstract
Plants are exposed to various environmental stresses. The sensing of environmental cues and the transduction of stress signals into intracellular signaling are initial events in the cellular signaling network. As a second messenger, Ca2+ links environmental stimuli to different biological processes, such as growth, physiology, and sensing of and response to stress. An increase in intracellular calcium concentrations ([Ca2+]i) is a common event in most stress-induced signal transduction pathways. In recent years, significant progress has been made in research related to the early events of stress signaling in plants, particularly in the identification of primary stress sensors. This review highlights current advances that are beginning to elucidate the mechanisms by which abiotic environmental cues are sensed via Ca2+ signals. Additionally, this review discusses important questions about the integration of the sensing of multiple stress conditions and subsequent signaling responses that need to be addressed in the future.
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Affiliation(s)
- Tongfei Xu
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Junfeng Niu
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Zhonghao Jiang
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
- *Correspondence: Zhonghao Jiang,
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16
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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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17
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MCAs in Arabidopsis are Ca 2+-permeable mechanosensitive channels inherently sensitive to membrane tension. Nat Commun 2021; 12:6074. [PMID: 34667173 PMCID: PMC8526687 DOI: 10.1038/s41467-021-26363-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 10/02/2021] [Indexed: 02/05/2023] Open
Abstract
Mechanosensitive (MS) ion channels respond to mechanical stress and convert it into intracellular electric and ionic signals. Five MS channel families have been identified in plants, including the Mid1-Complementing Activity (MCA) channel; however, its activation mechanisms have not been elucidated in detail. We herein demonstrate that the MCA2 channel is a Ca2+-permeable MS channel that is directly activated by membrane tension. The N-terminal 173 residues of MCA1 and MCA2 were synthesized in vitro, purified, and reconstituted into artificial liposomal membranes. Liposomes reconstituted with MCA1(1-173) or MCA2(1-173) mediate Ca2+ influx and the application of pressure to the membrane reconstituted with MCA2(1-173) elicits channel currents. This channel is also activated by voltage. Blockers for MS channels inhibit activation by stretch, but not by voltage. Since MCA proteins are found exclusively in plants, these results suggest that MCA represent plant-specific MS channels that open directly with membrane tension. Mechanosensitive ion channels convert mechanical stimuli into intracellular electric and ionic signals. Here the authors show that Arabidopsis MCA2 is a Ca2+-permeable mechanosensitive channel that is directly activated by membrane tension.
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18
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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: 6] [Impact Index Per Article: 2.0] [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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19
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Radin I, Richardson RA, Coomey JH, Weiner ER, Bascom CS, Li T, Bezanilla M, Haswell ES. Plant PIEZO homologs modulate vacuole morphology during tip growth. Science 2021; 373:586-590. [PMID: 34326243 DOI: 10.1126/science.abe6310] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 02/24/2021] [Accepted: 06/16/2021] [Indexed: 12/11/2022]
Abstract
In animals, PIEZOs are plasma membrane-localized cation channels involved in diverse mechanosensory processes. We investigated PIEZO function in tip-growing cells in the moss Physcomitrium patens and the flowering plant Arabidopsis thaliana PpPIEZO1 and PpPIEZO2 redundantly contribute to the normal growth, size, and cytoplasmic calcium oscillations of caulonemal cells. Both PpPIEZO1 and PpPIEZO2 localized to vacuolar membranes. Loss-of-function, gain-of-function, and overexpression mutants revealed that moss PIEZO homologs promote increased complexity of vacuolar membranes through tubulation, internalization, and/or fission. Arabidopsis PIEZO1 also localized to the tonoplast and is required for vacuole tubulation in the tips of pollen tubes. We propose that in plant cells the tonoplast has more freedom of movement than the plasma membrane, making it a more effective location for mechanosensory proteins.
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Affiliation(s)
- Ivan Radin
- Department of Biology and NSF Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Ryan A Richardson
- Department of Biology and NSF Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Joshua H Coomey
- Department of Biology and NSF Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Ethan R Weiner
- Department of Biology and NSF Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
| | | | - Ting Li
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | | | - Elizabeth S Haswell
- Department of Biology and NSF Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA.
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20
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Abstract
Our knowledge of plant ion channels was significantly enhanced by the first application of the patch-clamp technique to isolated guard cell protoplasts over 35 years ago. Since then, research has demonstrated the importance of ion channels in the control of gas exchange in guard cells, their role in nutrient uptake in roots, and the participation of calcium-permeable cation channels in the regulation of cell signaling affected by the intracellular concentrations of this second messenger. In recent years, through the employment of reverse genetics, mutant proteins, and heterologous expression systems, research on ion channels has identified mechanisms that modify their activity through protein-protein interactions or that result in activation and/or deactivation of ion channels through posttranslational modifications. Additional and confirmatory information on ion channel functioning has been derived from the crystallization and molecular modeling of plant proteins that, together with functional analyses, have helped to increase our knowledge of the functioning of these important membrane proteins that may eventually help to improve crop yield. Here, an update on the advances obtained in plant ion channel function during the last few years is presented.
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Affiliation(s)
- Omar Pantoja
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México;
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21
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Nestrerenko EO, Krasnoperova OE, Isayenkov SV. Potassium Transport Systems and Their Role in Stress Response, Plant Growth, and Development. CYTOL GENET+ 2021. [DOI: 10.3103/s0095452721010126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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22
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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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23
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The gravistimulation-induced very slow Ca 2+ increase in Arabidopsis seedlings requires MCA1, a Ca 2+-permeable mechanosensitive channel. Sci Rep 2021; 11:227. [PMID: 33420331 PMCID: PMC7794229 DOI: 10.1038/s41598-020-80733-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 12/23/2020] [Indexed: 12/11/2022] Open
Abstract
Gravity is a critical environmental factor affecting the morphology and function of plants on Earth. Gravistimulation triggered by changes in the gravity vector induces an increase in the cytoplasmic free calcium ion concentration ([Ca2+]c) as an early process of gravity sensing; however, its role and molecular mechanism are still unclear. When seedlings of Arabidopsis thaliana expressing apoaequorin were rotated from the upright position to the upside-down position, a biphasic [Ca2+]c-increase composed of a fast-transient [Ca2+]c-increase followed by a slow [Ca2+]c-increase was observed. We find here a novel type [Ca2+]c-increase, designated a very slow [Ca2+]c-increase that is observed when the seedlings were rotated back to the upright position from the upside-down position. The very slow [Ca2+]c-increase was strongly attenuated in knockout seedlings defective in MCA1, a mechanosensitive Ca2+-permeable channel (MSCC), and was partially restored in MCA1-complemented seedlings. The mechanosensitive ion channel blocker, gadolinium, blocked the very slow [Ca2+]c-increase. This is the first report suggesting the possible involvement of MCA1 in an early event related to gravity sensing in Arabidopsis seedlings.
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24
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Basu D, Shoots JM, Haswell ES. Interactions between the N- and C-termini of the mechanosensitive ion channel AtMSL10 are consistent with a three-step mechanism for activation. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:4020-4032. [PMID: 32280992 DOI: 10.1093/jxb/eraa192] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
Although a growing number of mechanosensitive ion channels are being identified in plant systems, the molecular mechanisms by which they function are still under investigation. Overexpression of the mechanosensitive ion channel MSL (MscS-Like)10 fused to green fluorescent protein (GFP) triggers a number of developmental and cellular phenotypes including the induction of cell death, and this function is influenced by seven phosphorylation sites in its soluble N-terminus. Here, we show that these and other phenotypes required neither overexpression nor a tag, and could also be induced by a previously identified point mutation in the soluble C-terminus (S640L). The promotion of cell death and hyperaccumulation of H2O2 in 35S:MSL10S640L-GFP overexpression lines was suppressed by N-terminal phosphomimetic substitutions, and the soluble N- and C-terminal domains of MSL10 physically interacted. We propose a three-step model by which tension-induced conformational changes in the C-terminus could be transmitted to the N-terminus, leading to its dephosphorylation and the induction of adaptive responses. Taken together, this work expands our understanding of the molecular mechanisms of mechanotransduction in plants.
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Affiliation(s)
- Debarati Basu
- NSF Center for Engineering Mechanobiology, Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| | - Jennette M Shoots
- NSF Center for Engineering Mechanobiology, Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
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25
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Abstract
Crop loss due to soil salinization is an increasing threat to agriculture worldwide. This review provides an overview of cellular and physiological mechanisms in plant responses to salt. We place cellular responses in a time- and tissue-dependent context in order to link them to observed phases in growth rate that occur in response to stress. Recent advances in phenotyping can now functionally or genetically link cellular signaling responses, ion transport, water management, and gene expression to growth, development, and survival. Halophytes, which are naturally salt-tolerant plants, are highlighted as success stories to learn from. We emphasize that (a) filling the major knowledge gaps in salt-induced signaling pathways, (b) increasing the spatial and temporal resolution of our knowledge of salt stress responses, (c) discovering and considering crop-specific responses, and (d) including halophytes in our comparative studies are all essential in order to take our approaches to increasing crop yields in saline soils to the next level.
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Affiliation(s)
- Eva van Zelm
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands;
| | - Yanxia Zhang
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands;
| | - Christa Testerink
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands;
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26
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Schlegel AM, Haswell ES. Analyzing plant mechanosensitive ion channels expressed in giant E. coli spheroplasts by single-channel patch-clamp electrophysiology. Methods Cell Biol 2020; 160:61-82. [PMID: 32896333 DOI: 10.1016/bs.mcb.2020.02.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Plants possess numerous ion channels that respond to a range of stimuli, including small molecules, transmembrane voltage, and mechanical force. Many in the latter category, known as mechanosensitive (MS) ion channels, open directly in response to increases in lateral membrane tension. One of the most effective techniques for characterizing ion channel properties is patch-clamp electrophysiology, in which the current through a section of membrane containing ion channels is measured. For MS channels, this technique enables the measurement of key channel properties such as tension sensitivity, conductance, and ion selectivity. These characteristics, along with the phenotypes of genetic mutants, can help reveal the physiological roles of a particular MS channel. In this protocol, we provide detailed instructions on how to study MS ion channels using single-channel patch-clamp electrophysiology in giant E. coli spheroplasts. We first present an optimized method for preparing giant spheroplasts, then describe how to measure MS channel activity using patch-clamp electrophysiology and analyze the resulting data. We also provide recommended equipment lists, setup schematics, and useful conventions.
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Affiliation(s)
- Angela M Schlegel
- Department of Biology and Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, United States
| | - Elizabeth S Haswell
- Department of Biology and Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, United States.
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27
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Frachisse JM, Thomine S, Allain JM. Calcium and plasma membrane force-gated ion channels behind development. CURRENT OPINION IN PLANT BIOLOGY 2020; 53:57-64. [PMID: 31783322 DOI: 10.1016/j.pbi.2019.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/17/2019] [Accepted: 10/21/2019] [Indexed: 06/10/2023]
Abstract
During development, tissues are submitted to high variation of compression and tension forces. The roles of the cell wall, the cytoskeleton, the turgor pressure and the cell geometry during this process have received due attention. In contrast, apart from its role in the establishment of turgor pressure, the involvement of the plasma membrane as a transducer of mechanical forces during development has been under studied. Force-gated (FG) or Mechanosensitive (MS) ion channels embedded in the bilayer represent 'per se' archetypal mechanosensor able to directly and instantaneously transduce membrane forces into electrical and calcium signals. We discuss here how their fine-tuning, combined with their ability to detect micro-curvature and local membrane tension, allows FG channels to transduce mechanical cues into developmental signals.
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Affiliation(s)
- Jean-Marie Frachisse
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Sciences Plant Saclay, 91198 Gif sur Yvette Cedex, France.
| | - Sébastien Thomine
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Sciences Plant Saclay, 91198 Gif sur Yvette Cedex, France
| | - Jean-Marc Allain
- LMS, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France; Inria, Palaiseau, France.
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28
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Quantitative and functional posttranslational modification proteomics reveals that TREPH1 plays a role in plant touch-delayed bolting. Proc Natl Acad Sci U S A 2018; 115:E10265-E10274. [PMID: 30291188 DOI: 10.1073/pnas.1814006115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Environmental mechanical forces, such as wind and touch, trigger gene-expression regulation and developmental changes, called "thigmomorphogenesis," in plants, demonstrating the ability of plants to perceive such stimuli. In Arabidopsis, a major thigmomorphogenetic response is delayed bolting, i.e., emergence of the flowering stem. The signaling components responsible for mechanotransduction of the touch response are largely unknown. Here, we performed a high-throughput SILIA (stable isotope labeling in Arabidopsis)-based quantitative phosphoproteomics analysis to profile changes in protein phosphorylation resulting from 40 seconds of force stimulation in Arabidopsis thaliana Of the 24 touch-responsive phosphopeptides identified, many were derived from kinases, phosphatases, cytoskeleton proteins, membrane proteins, and ion transporters. In addition, the previously uncharacterized protein TOUCH-REGULATED PHOSPHOPROTEIN1 (TREPH1) became rapidly phosphorylated in touch-stimulated plants, as confirmed by immunoblots. TREPH1 fractionates as a soluble protein and is shown to be required for the touch-induced delay of bolting and gene-expression changes. Furthermore, a nonphosphorylatable site-specific isoform of TREPH1 (S625A) failed to restore touch-induced flowering delay of treph1-1, indicating the necessity of S625 for TREPH1 function and providing evidence consistent with the possible functional relevance of the touch-regulated TREPH1 phosphorylation. Taken together, these findings identify a phosphoprotein player in Arabidopsis thigmomorphogenesis regulation and provide evidence that TREPH1 and its touch-induced phosphorylation may play a role in touch-induced bolting delay, a major component of thigmomorphogenesis.
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29
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Wang S, Song M, Guo J, Huang Y, Zhang F, Xu C, Xiao Y, Zhang L. The potassium channel FaTPK1 plays a critical role in fruit quality formation in strawberry ( Fragaria × ananassa). PLANT BIOTECHNOLOGY JOURNAL 2018; 16:737-748. [PMID: 28851008 PMCID: PMC5814577 DOI: 10.1111/pbi.12824] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 07/30/2017] [Accepted: 08/12/2017] [Indexed: 05/07/2023]
Abstract
Potassium (K+), an abundant cation in plant cells, is important in fruit development and plant resistance. However, how cellular K+ is directed by potassium channels in fruit development and quality formation of strawberry (Fragaria × ananassa) is not yet fully clear. Here, a two‐pore K+ (TPK) channel gene in strawberry, FaTPK1, was cloned using reverse transcription–PCR. A green fluorescent protein subcellular localization analysis showed that FaTPK1 localized in the vacuole membrane. A transcription analysis indicated that the mRNA expression level of FaTPK1 increased rapidly and was maintained at a high level in ripened fruit, which was coupled with the fruit's red colour development, suggesting that FaTPK1 is related to fruit quality formation. The down‐ and up‐regulation of the FaTPK1mRNA expression levels using RNA interference and overexpression, respectively, inhibited and promoted fruit ripening, respectively, as demonstrated by consistent changes in firmness and the contents of soluble sugars, anthocyanin and abscisic acid, as well as the transcript levels of ripening‐regulated genes PG1 (polygalacturonase), GAL6 (beta‐galactosidase), XYL2 (D‐xylulose reductase), SUT1 (sucrose transporter), CHS (chalcone synthase) and CHI (chalcone flavanone isomerase). Additionally, the regulatory changes influenced fruit resistance to Botrytis cinerea. An isothermal calorimetry analysis showed that the Escherichia coli‐expressed FaTPK1 recombinant protein could bind K+ with a binding constant of 2.1 × 10–3 m−1 and a dissociation constant of 476 μm. Thus, the strawberry TPK1 is a ubiquitously expressed, tonoplast‐localized two‐pore potassium channel that plays important roles in fruit ripening and quality formation.
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Affiliation(s)
- Shufang Wang
- College of HorticultureChina Agricultural UniversityBeijingChina
- Department of resources and environmentBeijing University of AgricultureBeijingChina
| | - Miaoyu Song
- Department of resources and environmentBeijing University of AgricultureBeijingChina
| | - Jiaxuan Guo
- Department of resources and environmentBeijing University of AgricultureBeijingChina
| | - Yun Huang
- Department of resources and environmentBeijing University of AgricultureBeijingChina
| | - Fangfang Zhang
- College of HorticultureChina Agricultural UniversityBeijingChina
| | - Cheng Xu
- College of HorticultureChina Agricultural UniversityBeijingChina
| | - Yinghui Xiao
- College of HorticultureChina Agricultural UniversityBeijingChina
| | - Lusheng Zhang
- College of HorticultureChina Agricultural UniversityBeijingChina
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30
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Formentin E, Sudiro C, Perin G, Riccadonna S, Barizza E, Baldoni E, Lavezzo E, Stevanato P, Sacchi GA, Fontana P, Toppo S, Morosinotto T, Zottini M, Lo Schiavo F. Transcriptome and Cell Physiological Analyses in Different Rice Cultivars Provide New Insights Into Adaptive and Salinity Stress Responses. FRONTIERS IN PLANT SCIENCE 2018; 9:204. [PMID: 29556243 PMCID: PMC5844958 DOI: 10.3389/fpls.2018.00204] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 02/02/2018] [Indexed: 05/20/2023]
Abstract
Salinity tolerance has been extensively investigated in recent years due to its agricultural importance. Several features, such as the regulation of ionic transporters and metabolic adjustments, have been identified as salt tolerance hallmarks. Nevertheless, due to the complexity of the trait, the results achieved to date have met with limited success in improving the salt tolerance of rice plants when tested in the field, thus suggesting that a better understanding of the tolerance mechanisms is still required. In this work, differences between two varieties of rice with contrasting salt sensitivities were revealed by the imaging of photosynthetic parameters, ion content analysis and a transcriptomic approach. The transcriptomic analysis conducted on tolerant plants supported the setting up of an adaptive program consisting of sodium distribution preferentially limited to the roots and older leaves, and in the activation of regulatory mechanisms of photosynthesis in the new leaves. As a result, plants resumed grow even under prolonged saline stress. In contrast, in the sensitive variety, RNA-seq analysis revealed a misleading response, ending in senescence and cell death. The physiological response at the cellular level was investigated by measuring the intracellular profile of H2O2 in the roots, using a fluorescent probe. In the roots of tolerant plants, a quick response was observed with an increase in H2O2 production within 5 min after salt treatment. The expression analysis of some of the genes involved in perception, signal transduction and salt stress response confirmed their early induction in the roots of tolerant plants compared to sensitive ones. By inhibiting the synthesis of apoplastic H2O2, a reduction in the expression of these genes was detected. Our results indicate that quick H2O2 signaling in the roots is part of a coordinated response that leads to adaptation instead of senescence in salt-treated rice plants.
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Affiliation(s)
- Elide Formentin
- Department of Biology, University of Padova, Padova, Italy
- *Correspondence: Elide Formentin,
| | | | - Giorgio Perin
- Department of Biology, University of Padova, Padova, Italy
| | - Samantha Riccadonna
- Research and Innovation Centre, Edmund Mach Foundation, San Michele all’Adige, Italy
| | | | - Elena Baldoni
- Department of Agricultural and Environmental Sciences - Production, Landscape, Agroenergy, University of Milan, Milan, Italy
| | - Enrico Lavezzo
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Piergiorgio Stevanato
- Department of Agronomy, Food, Natural Resources, Animals and the Environment, University of Padova, Padova, Italy
| | - Gian Attilio Sacchi
- Department of Agricultural and Environmental Sciences - Production, Landscape, Agroenergy, University of Milan, Milan, Italy
| | - Paolo Fontana
- Research and Innovation Centre, Edmund Mach Foundation, San Michele all’Adige, Italy
| | - Stefano Toppo
- Department of Molecular Medicine, University of Padova, Padova, Italy
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31
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Basu D, Haswell ES. Plant mechanosensitive ion channels: an ocean of possibilities. CURRENT OPINION IN PLANT BIOLOGY 2017; 40:43-48. [PMID: 28750206 PMCID: PMC5714682 DOI: 10.1016/j.pbi.2017.07.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 06/26/2017] [Accepted: 07/09/2017] [Indexed: 05/19/2023]
Abstract
Mechanosensitive ion channels, transmembrane proteins that directly couple mechanical stimuli to ion flux, serve to sense and respond to changes in membrane tension in all branches of life. In plants, mechanosensitive channels have been implicated in the perception of important mechanical stimuli such as osmotic pressure, touch, gravity, and pathogenic invasion. Indeed, three established families of plant mechanosensitive ion channels play roles in cell and organelle osmoregulation and root mechanosensing - and it is likely that many other channels and functions await discovery. Inspired by recent discoveries in bacterial and animal systems, we are beginning to establish the conserved and the unique ways in which mechanosensitive channels function in plants.
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Affiliation(s)
- Debarati Basu
- Department of Biology, Mailcode 1137, Washington University in Saint Louis, Saint Louis, MO 63130, USA
| | - Elizabeth S Haswell
- Department of Biology, Mailcode 1137, Washington University in Saint Louis, Saint Louis, MO 63130, USA.
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Abstract
There is increasing evidence that all cells sense mechanical forces in order to perform their functions. In animals, mechanotransduction has been studied during the establishment of cell polarity, fate, and division in single cells, and increasingly is studied in the context of a multicellular tissue. What about plant systems? Our goal in this review is to summarize what is known about the perception of mechanical cues in plants, and to provide a brief comparison with animals.
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Affiliation(s)
- Olivier Hamant
- Laboratoire Reproduction et Développement des Plantes, University Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342, Lyon, France.
| | - Elizabeth S Haswell
- Department of Biology, Washington University in Saint Louis, Mailbox 1137, Saint Louis, MO, 63130, USA.
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33
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Hamant O, Haswell ES. Life behind the wall: sensing mechanical cues in plants. BMC Biol 2017. [PMID: 28697754 DOI: 10.1186/s12915-017-0403-405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
There is increasing evidence that all cells sense mechanical forces in order to perform their functions. In animals, mechanotransduction has been studied during the establishment of cell polarity, fate, and division in single cells, and increasingly is studied in the context of a multicellular tissue. What about plant systems? Our goal in this review is to summarize what is known about the perception of mechanical cues in plants, and to provide a brief comparison with animals.
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Affiliation(s)
- Olivier Hamant
- Laboratoire Reproduction et Développement des Plantes, University Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342, Lyon, France.
| | - Elizabeth S Haswell
- Department of Biology, Washington University in Saint Louis, Mailbox 1137, Saint Louis, MO, 63130, USA.
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34
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Pérez Koldenkova V, Hatsugai N. Vacuolar convolution: possible mechanisms and role of phosphatidylinositol 3,5-bisphosphate. FUNCTIONAL PLANT BIOLOGY : FPB 2017; 44:751-760. [PMID: 32480604 DOI: 10.1071/fp16443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 05/19/2017] [Indexed: 06/11/2023]
Abstract
The central or lytic vacuole is the largest intracellular organelle in plant cells, but we know unacceptably little about the mechanisms regulating its function in vivo. The underlying reasons are related to difficulties in accessing this organelle without disrupting the cellular integrity and to the dynamic morphology of the vacuole, which lacks a defined structure. Among such morphological changes, vacuolar convolution is probably the most commonly observed event, reflected in the (reversible) transformation of a large central vacuole into a structure consisting of interconnected bubbles of a smaller size. Such behaviour is observed in plant cells subjected to hyperosmotic stress but also takes place in physiological conditions (e.g. during stomatal closure). Although vacuolar convolution is a relatively common phenomenon in plants, studies aimed at elucidating its execution mechanisms are rather scarce. In the present review, we analyse the available evidence on the participation of the cellular cytoskeleton and ion transporters in vacuolar morphology dynamics, putting special emphasis on the available evidence of the role played by phosphatidylinositol 3,5-bisphosphate in this process.
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Affiliation(s)
- Vadim Pérez Koldenkova
- Laboratorio Nacional de Microscopía Avanzada, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Av. Cuauhtémoc, 330, Col. Doctores, Del. Cuauhtémoc. 06720, México D.F., Mexico
| | - Noriyuki Hatsugai
- Department of Plant Biology, Microbial and Plant Genomics Institute, University of Minnesota St Paul, MN 55108, USA
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35
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Nieves-Cordones M, Al Shiblawi FR, Sentenac H. Roles and Transport of Sodium and Potassium in Plants. Met Ions Life Sci 2016; 16:291-324. [PMID: 26860305 DOI: 10.1007/978-3-319-21756-7_9] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The two alkali cations Na(+) and K(+) have similar relative abundances in the earth crust but display very different distributions in the biosphere. In all living organisms, K(+) is the major inorganic cation in the cytoplasm, where its concentration (ca. 0.1 M) is usually several times higher than that of Na(+). Accumulation of Na(+) at high concentrations in the cytoplasm results in deleterious effects on cell metabolism, e.g., on photosynthetic activity in plants. Thus, Na(+) is compartmentalized outside the cytoplasm. In plants, it can be accumulated at high concentrations in vacuoles, where it is used as osmoticum. Na(+) is not an essential element in most plants, except in some halophytes. On the other hand, it can be a beneficial element, by replacing K(+) as vacuolar osmoticum for instance. In contrast, K(+) is an essential element. It is involved in electrical neutralization of inorganic and organic anions and macromolecules, pH homeostasis, control of membrane electrical potential, and the regulation of cell osmotic pressure. Through the latter function in plants, it plays a role in turgor-driven cell and organ movements. It is also involved in the activation of enzymes, protein synthesis, cell metabolism, and photosynthesis. Thus, plant growth requires large quantities of K(+) ions that are taken up by roots from the soil solution, and then distributed throughout the plant. The availability of K(+) ions in the soil solution, slowly released by soil particles and clays, is often limiting for optimal growth in most natural ecosystems. In contrast, due to natural salinity or irrigation with poor quality water, detrimental Na(+) concentrations, toxic for all crop species, are present in many soils, representing 6 % to 10 % of the earth's land area. Three families of ion channels (Shaker, TPK/KCO, and TPC) and 3 families of transporters (HAK, HKT, and CPA) have been identified so far as contributing to K(+) and Na(+) transport across the plasmalemma and internal membranes, with high or low ionic selectivity. In the model plant Arabidopsis thaliana, these families gather at least 70 members. Coordination of the activities of these systems, at the cell and whole plant levels, ensures plant K(+) nutrition, use of Na(+) as a beneficial element, and adaptation to saline conditions.
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Affiliation(s)
- Manuel Nieves-Cordones
- Laboratory of Plant Biochemistry and Molecular Physiology, UMR BPMP CNRS/INRA/MontpellierSupAgro, University of Montpellier, INRA, Place Viala, F-34060, Montpellier cedex 1, France
| | - Fouad Razzaq Al Shiblawi
- Laboratory of Plant Biochemistry and Molecular Physiology, UMR BPMP CNRS/INRA/MontpellierSupAgro, University of Montpellier, INRA, Place Viala, F-34060, Montpellier cedex 1, France
| | - Hervé Sentenac
- Laboratory of Plant Biochemistry and Molecular Physiology, UMR BPMP CNRS/INRA/MontpellierSupAgro, University of Montpellier, INRA, Place Viala, F-34060, Montpellier cedex 1, France.
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36
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Ahmad I, Devonshire J, Mohamed R, Schultze M, Maathuis FJM. Overexpression of the potassium channel TPKb in small vacuoles confers osmotic and drought tolerance to rice. THE NEW PHYTOLOGIST 2016; 209:1040-8. [PMID: 26474307 DOI: 10.1111/nph.13708] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 09/04/2015] [Indexed: 05/21/2023]
Abstract
Potassium (K(+) ) is the most important cationic nutrient for all living organisms. Vacuolar two-pore K(+) (TPK) channels are important players in the regulation of cellular levels of K(+) but have not been characterised in rice. In order to assess the role of OsTPKb, a K(+) selective ion channel predominantly expressed in the tonoplast of small vacuoles, we generated overexpressing (OX) lines using a constitutive promoter and compared their phenotypes with control plants. Relative to control plants, OX lines showed better growth when exposed to low-K(+) or water stress conditions. K(+) uptake was greater in OX lines which may be driven by increased AKT1 and HAK1 activity. The enhanced K(+) uptake led to tissue K(+) levels that were raised in roots and shoots. Furthermore, energy dispersive X-ray (EDX) analyses showed a higher cytoplasm: vacuole K(+) ratio which is likely to contribute to the increased stress tolerance. In all, the data suggest that TPKb can alter the K(+) status of small vacuoles, which is important for general cellular K(+) homeostasis which, in turn, affects stress tolerance.
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Affiliation(s)
- Izhar Ahmad
- Department of Biology, University of York, York, YO10 5DD, UK
| | | | - Radwa Mohamed
- Department of Biology, University of York, York, YO10 5DD, UK
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37
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Hartley TN, Maathuis FJM. Allelic variation in the vacuolar TPK1 channel affects its calcium dependence and may impact on stomatal conductance. FEBS Lett 2015; 590:110-7. [DOI: 10.1002/1873-3468.12035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 10/30/2015] [Accepted: 11/28/2015] [Indexed: 11/05/2022]
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38
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Coordination and fine motor control depend on Drosophila TRPγ. Nat Commun 2015; 6:7288. [PMID: 26028119 DOI: 10.1038/ncomms8288] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 04/26/2015] [Indexed: 12/31/2022] Open
Abstract
Motor coordination is broadly divided into gross and fine motor control, both of which depend on proprioceptive organs. However, the channels that function specifically in fine motor control are unknown. Here we show that mutations in trpγ disrupt fine motor control while leaving gross motor proficiency intact. The mutants are unable to coordinate precise leg movements during walking, and are ineffective in traversing large gaps due to an inability in making subtle postural adaptations that are requisite for this task. TRPγ is expressed in proprioceptive organs, and is required in both neurons and glia for gap crossing. We expressed TRPγ in vitro, and found that its activity is promoted by membrane stretch. A mutation eliminating the Na(+)/Ca(2+) exchanger suppresses the gap-crossing phenotype of trpγ flies. Our findings indicate that TRPγ contributes to fine motor control through mechanical activation in proprioceptive organs, thereby promoting Ca(2+) influx, which is required for function.
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39
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Haswell ES, Verslues PE. The ongoing search for the molecular basis of plant osmosensing. ACTA ACUST UNITED AC 2015; 145:389-94. [PMID: 25870206 PMCID: PMC4411250 DOI: 10.1085/jgp.201411295] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Elizabeth S Haswell
- Department of Biology, Washington University in Saint Louis, Saint Louis, MO 63130
| | - Paul E Verslues
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
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40
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Are Aquaporins the Missing Transmembrane Osmosensors? J Membr Biol 2015; 248:753-65. [PMID: 25791748 DOI: 10.1007/s00232-015-9790-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/12/2015] [Indexed: 01/08/2023]
Abstract
Regulation of cell volume is central to homeostasis. It is assumed to begin with the detection of a change in water potential across the bounding membrane, but it is not clear how this is accomplished. While examples of general osmoreceptors (which sense osmotic pressure in one phase) and stretch-activated ion channels (which require swelling of a cell or organelle) are known, effective volume regulation requires true transmembrane osmosensors (TMOs) which directly detect a water potential difference spanning a membrane. At present, no TMO molecule has been unambiguously identified, and clear evidence for mammalian TMOs is notably lacking. In this paper, we set out a theory of TMOs which requires a water channel spanning the membrane that excludes the major osmotic solutes, responds directly without the need for any other process such as swelling, and signals to other molecules associated with the magnitude of changing osmotic differences. The most likely molecules that are fit for this purpose and which are also ubiquitous in eukaryotic cells are aquaporins (AQPs). We review experimental evidence from several systems which indicates that AQPs are essential elements in regulation and may be functioning as TMOs; i.e. the first step in an osmosensing sequence that signals osmotic imbalance in a cell or organelle. We extend this concept to several systems of current interest in which the cellular involvement of AQPs as simple water channels is puzzling or counter-intuitive. We suggest that, apart from regulatory volume changes in cells, AQPs may also be acting as TMOs in red cells, secretory granules and microorganisms.
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41
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Hamilton ES, Schlegel AM, Haswell ES. United in diversity: mechanosensitive ion channels in plants. ANNUAL REVIEW OF PLANT BIOLOGY 2014; 66:113-37. [PMID: 25494462 PMCID: PMC4470482 DOI: 10.1146/annurev-arplant-043014-114700] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Mechanosensitive (MS) ion channels are a common mechanism for perceiving and responding to mechanical force. This class of mechanoreceptors is capable of transducing membrane tension directly into ion flux. In plant systems, MS ion channels have been proposed to play a wide array of roles, from the perception of touch and gravity to the osmotic homeostasis of intracellular organelles. Three families of plant MS ion channels have been identified: the MscS-like (MSL), Mid1-complementing activity (MCA), and two-pore potassium (TPK) families. Channels from these families vary widely in structure and function, localize to multiple cellular compartments, and conduct chloride, calcium, and/or potassium ions. However, they are still likely to represent only a fraction of the MS ion channel diversity in plant systems.
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Affiliation(s)
- Eric S. Hamilton
- Department of Biology, Washington University in Saint Louis, Saint Louis, Missouri 63130
| | - Angela M. Schlegel
- Department of Biology, Washington University in Saint Louis, Saint Louis, Missouri 63130
| | - Elizabeth S. Haswell
- Department of Biology, Washington University in Saint Louis, Saint Louis, Missouri 63130
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42
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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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43
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Shabala S, Pottosin I. Regulation of potassium transport in plants under hostile conditions: implications for abiotic and biotic stress tolerance. PHYSIOLOGIA PLANTARUM 2014; 151:257-79. [PMID: 24506225 DOI: 10.1111/ppl.12165] [Citation(s) in RCA: 274] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/15/2013] [Accepted: 01/13/2014] [Indexed: 05/18/2023]
Abstract
Intracellular potassium homeostasis is a prerequisite for the optimal operation of plant metabolic machinery and plant's overall performance. It is controlled by K(+) uptake, efflux and intracellular and long-distance relocation, mediated by a large number of K(+) -selective and non-selective channels and transporters located at both plasma and vacuolar membranes. All abiotic and biotic stresses result in a significant disturbance to intracellular potassium homeostasis. In this work, we discuss molecular mechanisms and messengers mediating potassium transport and homeostasis focusing on four major environmental stresses: salinity, drought, flooding and biotic factors. We argue that cytosolic K(+) content may be considered as one of the 'master switches' enabling plant transition from the normal metabolism to 'hibernated state' during first hours after the stress exposure and then to a recovery phase. We show that all these stresses trigger substantial disturbance to K(+) homeostasis and provoke a feedback control on K(+) channels and transporters expression and post-translational regulation of their activity, optimizing K(+) absorption and usage, and, at the extreme end, assisting the programmed cell death. We discuss specific modes of regulation of the activity of K(+) channels and transporters by membrane voltage, intracellular Ca(2+) , reactive oxygen species, polyamines, phytohormones and gasotransmitters, and link this regulation with plant-adaptive responses to hostile environments.
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Affiliation(s)
- Sergey Shabala
- School of Agricultural Science, University of Tasmania, Hobart, Tas, 7001, Australia
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44
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Pottosin I, Dobrovinskaya O. Non-selective cation channels in plasma and vacuolar membranes and their contribution to K+ transport. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:732-42. [PMID: 24560436 DOI: 10.1016/j.jplph.2013.11.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 11/21/2013] [Accepted: 11/22/2013] [Indexed: 05/25/2023]
Abstract
Both in vacuolar and plasma membranes, in addition to truly K(+)-selective channels there is a variety of non-selective channels, which conduct K(+) and other ions with little preference. Many non-selective channels in the plasma membrane are active at depolarized potentials, thus, contributing to K(+) efflux rather than to K(+) uptake. They may play important roles in xylem loading or contribute to a K(+) leak, induced by salt or oxidative stress. Here, three currents, expressed in root cells, are considered: voltage-insensitive cation current, non-selective outwardly rectifying current, and low-selective conductance, activated by reactive oxygen species. The latter two do not only poorly discriminate between different cations (like K(+)vs Na(+)), but also conduct anions. Such solute channels may mediate massive electroneutral transport of salts and might be involved in osmotic adjustment or volume decrease, associated with cell death. In the tonoplast two major currents are mediated by SV (slow) and FV (fast) vacuolar channels, respectively, which are virtually impermeable for anions. SV channels conduct mono- and divalent cations indiscriminately and are activated by high cytosolic Ca(2+) and depolarized voltages. FV channels are inhibited by micromolar cytosolic Ca(2+), Mg(2+), and polyamines, and conduct a variety of monovalent cations, including K(+). Strikingly, both SV and FV channels sense the K(+) content of vacuoles, which modulates their voltage dependence, and in case of SV, also alleviates channel's inhibition by luminal Ca(2+). Therefore, SV and FV channels may operate as K(+)-sensing valves, controlling K(+) distribution between the vacuole and the cytosol.
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Affiliation(s)
- Igor Pottosin
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de julio 965, Villa de San Sebastián, 28045 Colima, Mexico.
| | - Oxana Dobrovinskaya
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de julio 965, Villa de San Sebastián, 28045 Colima, Mexico
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45
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Tatsumi H, Toyota M, Furuichi T, Sokabe M. Calcium mobilizations in response to changes in the gravity vector in Arabidopsis seedlings: possible cellular mechanisms. PLANT SIGNALING & BEHAVIOR 2014; 9:e29099. [PMID: 25763612 PMCID: PMC4203510 DOI: 10.4161/psb.29099] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/02/2014] [Accepted: 05/02/2014] [Indexed: 05/11/2023]
Abstract
Gravity influences the growth direction of higher plants. Changes in the gravity vector (gravistimulation) immediately promote the increase in the cytoplasmic free calcium ion concentration ([Ca(2+)]c) in Arabidopsis (Arabidopsis thaliana) seedlings. When the seedlings are gravistimulated by reorientation at 180°, a transient two peaked (biphasic) [Ca(2+)]c-increase arises in their hypocotyl and petioles. Parabolic flights (PFs) can generate a variety of gravity-stimuli, and enables us to measure gravity-induced [Ca(2+)]c-increases without specimen rotation, which demonstrate that Arabidopsis seedlings possess a rapid gravity-sensing mechanism linearly transducing a wide range of gravitational changes into Ca(2+) signals on a sub-second timescale. Hypergravity by centrifugation (20 g or 300 g) also induces similar transient [Ca(2+)]c-increases. In this review, we propose models for possible cellular processes of the garavi-stimulus-induced [Ca(2+)]c-increase, and evaluate those by examining whether the model fits well with the kinetic parameters derived from the [Ca(2+)]c-increases obtained by applying gravistimulus with different amplitudes and time sequences.
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Affiliation(s)
- Hitoshi Tatsumi
- Nagoya University Graduate School of Medicine; Nagoya, Japan
| | - Masatsugu Toyota
- Department of Botany; University of Wisconsin; Madison, WI USA
- Precursory Research for Embryonic Science and Technology (PRESTO); Japan Science and Technology Agency (JST); Kawaguchi, Saitama, Japan
| | - Takuya Furuichi
- Department of Health and Nutrition; Gifu Women’s University; Gifu, Japan
| | - Masahiro Sokabe
- Nagoya University Graduate School of Medicine; Nagoya, Japan
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46
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Peyronnet R, Tran D, Girault T, Frachisse JM. Mechanosensitive channels: feeling tension in a world under pressure. FRONTIERS IN PLANT SCIENCE 2014; 5:558. [PMID: 25374575 PMCID: PMC4204436 DOI: 10.3389/fpls.2014.00558] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 09/29/2014] [Indexed: 05/02/2023]
Abstract
Plants, like other organisms, are facing multiple mechanical constraints generated both in their tissues and by the surrounding environments. They need to sense and adapt to these forces throughout their lifetimes. To do so, different mechanisms devoted to force transduction have emerged. Here we focus on fascinating proteins: the mechanosensitive (MS) channels. Mechanosensing in plants has been described for centuries but the molecular identification of MS channels occurred only recently. This review is aimed at plant biologists and plant biomechanists who want to be introduced to MS channel identity, how they work and what they might do in planta? In this review, electrophysiological properties, regulations, and functions of well-characterized MS channels belonging to bacteria and animals are compared with those of plants. Common and specific properties are discussed. We deduce which tools and concepts from animal and bacterial fields could be helpful for improving our understanding of plant mechanotransduction. MS channels embedded in their plasma membrane are sandwiched between the cell wall and the cytoskeleton. The consequences of this peculiar situation are analyzed and discussed. We also stress how important it is to probe mechanical forces at cellular and subcellular levels in planta in order to reveal the intimate relationship linking the membrane with MS channel activity. Finally we will propose new tracks to help to reveal their physiological functions at tissue and plant levels.
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Affiliation(s)
- Rémi Peyronnet
- National Heart and Lung Institute, Imperial College LondonLondon, UK
| | - Daniel Tran
- Institut des Sciences du Végétal – Centre National de la Recherche Scientifique, Saclay Plant SciencesGif-sur-Yvette, France
| | - Tiffanie Girault
- Institut des Sciences du Végétal – Centre National de la Recherche Scientifique, Saclay Plant SciencesGif-sur-Yvette, France
| | - Jean-Marie Frachisse
- Institut des Sciences du Végétal – Centre National de la Recherche Scientifique, Saclay Plant SciencesGif-sur-Yvette, France
- *Correspondence: Jean-Marie Frachisse, Institut des Sciences du Végétal – Centre National de la Recherche Scientifique, Saclay Plant Sciences, Bat 22-23A, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France e-mail:
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Shachar-Hill B, Hill AE, Powell J, Skepper JN, Shachar-Hill Y. Mercury-sensitive water channels as possible sensors of water potentials in pollen. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:5195-205. [PMID: 24098048 PMCID: PMC3830494 DOI: 10.1093/jxb/ert311] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The growing pollen tube is central to plant reproduction and is a long-standing model for cellular tip growth in biology. Rapid osmotically driven growth is maintained under variable conditions, which requires osmosensing and regulation. This study explores the mechanism of water entry and the potential role of osmosensory regulation in maintaining pollen growth. The osmotic permeability of the plasmalemma of Lilium pollen tubes was measured from plasmolysis rates to be 1.32±0.31×10(-3) cm s(-1). Mercuric ions reduce this permeability by 65%. Simulations using an osmotic model of pollen tube growth predict that an osmosensor at the cell membrane controls pectin deposition at the cell tip; inhibiting the sensor is predicted to cause tip bursting due to cell wall thinning. It was found that adding mercury to growing pollen tubes caused such a bursting of the tips. The model indicates that lowering the osmotic permeability per se does not lead to bursting but rather to thickening of the tip. The time course of induced bursting showed no time lag and was independent of mercury concentration, compatible with a surface site of action. The submaximal bursting response to intermediate mercuric ion concentration was independent of the concentration of calcium ions, showing that bursting is not due to a competitive inhibition of calcium binding or entry. Bursting with the same time course was also shown by cells growing on potassium-free media, indicating that potassium channels (implicated in mechanosensing) are not involved in the bursting response. The possible involvement of mercury-sensitive water channels as osmosensors and current knowledge of these in pollen cells are discussed.
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Affiliation(s)
| | - Adrian E. Hill
- Department of Physiology, Development and Neuroscience, Cambridge University, Cambridge, UK
- * To whom correspondence should be addressed. E-mail:
| | - Janet Powell
- Multi-Imaging Centre, Cambridge University, Cambridge, UK
| | | | - Yair Shachar-Hill
- Department of Plant Biology, Plant Biology Building, Michigan State University, East Lansing, MI 48824-1312, USA
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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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