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Ishikawa T, Shabala L, Zhou M, Venkataraman G, Yu M, Sellamuthu G, Chen ZH, Shabala S. Comparative Analysis of Root Na+ Relation under Salinity between Oryza sativa and Oryza coarctata. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11050656. [PMID: 35270125 PMCID: PMC8912616 DOI: 10.3390/plants11050656] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 02/23/2022] [Accepted: 02/23/2022] [Indexed: 06/01/2023]
Abstract
Na+ toxicity is one of the major physiological constraints imposed by salinity on plant performance. At the same time, Na+ uptake may be beneficial under some circumstances as an easily accessible inorganic ion that can be used for increasing solute concentrations and maintaining cell turgor. Two rice species, Oryza sativa (cultivated rice, salt-sensitive) and Oryza coarctata (wild rice, salt-tolerant), demonstrated different strategies in controlling Na+ uptake. Glasshouse experiments and gene expression analysis suggested that salt-treated wild rice quickly increased xylem Na+ loading for osmotic adjustment but maintained a non-toxic level of stable shoot Na+ concentration by increased activity of a high affinity K+ transporter HKT1;5 (essential for xylem Na+ unloading) and a Na+/H+ exchanger NHX (for sequestering Na+ and K+ into root vacuoles). Cultivated rice prevented Na+ uptake and transport to the shoot at the beginning of salt treatment but failed to maintain it in the long term. While electrophysiological assays revealed greater net Na+ uptake upon salt application in cultivated rice, O. sativa plants showed much stronger activation of the root plasma membrane Na+/H+ Salt Overly Sensitive 1 (SOS1) exchanger. Thus, it appears that wild rice limits passive Na+ entry into root cells while cultivated rice relies heavily on SOS1-mediating Na+ exclusion, with major penalties imposed by the existence of the "futile cycle" at the plasma membrane.
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Affiliation(s)
- Tetsuya Ishikawa
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, TAS 7005, Australia; (T.I.); (L.S.); (M.Z.)
| | - Lana Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, TAS 7005, Australia; (T.I.); (L.S.); (M.Z.)
| | - Meixue Zhou
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, TAS 7005, Australia; (T.I.); (L.S.); (M.Z.)
| | - Gayatri Venkataraman
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600113, India; (G.V.); (G.S.)
| | - Min Yu
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China;
| | - Gothandapani Sellamuthu
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600113, India; (G.V.); (G.S.)
- Forest Molecular Entomology Lab, Excellent Team for Mitigation (ETM), Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, 16500 Prague, Czech Republic
| | - Zhong-Hua Chen
- School of Science, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia;
| | - Sergey Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, TAS 7005, Australia; (T.I.); (L.S.); (M.Z.)
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China;
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Qu Y, Guan R, Bose J, Henderson SW, Wege S, Qiu L, Gilliham M. Soybean CHX-type ion transport protein GmSALT3 confers leaf Na + exclusion via a root derived mechanism, and Cl - exclusion via a shoot derived process. PLANT, CELL & ENVIRONMENT 2021; 44:856-869. [PMID: 33190315 DOI: 10.1111/pce.13947] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 10/23/2020] [Accepted: 10/27/2020] [Indexed: 06/11/2023]
Abstract
Soybean (Glycine max) yields are threatened by multiple stresses including soil salinity. GmSALT3 (a cation-proton exchanger protein) confers net shoot exclusion for both Na+ and Cl- and improves salt tolerance of soybean; however, how the ER-localized GmSALT3 achieves this is unknown. Here, GmSALT3's function was investigated in heterologous systems and near isogenic lines that contained the full-length GmSALT3 (NIL-T; salt-tolerant) or a truncated transcript Gmsalt3 (NIL-S; salt-sensitive). GmSALT3 restored growth of K+ -uptake-defective Escherichia coli and contributed towards net influx and accumulation of Na+ , K+ and Cl- in Xenopus laevis oocytes, while Gmsalt3 was non-functional. Time-course analysis of NILs confirmed shoot Cl- exclusion occurs distinctly from Na+ exclusion. Grafting showed that shoot Na+ exclusion occurs via a root xylem-based mechanism; in contrast, NIL-T plants exhibited significantly greater Cl- content in both the stem xylem and phloem sap compared to NIL-S, indicating that shoot Cl- exclusion likely depends upon novel phloem-based Cl- recirculation. NIL-T shoots grafted on NIL-S roots contained low shoot Cl- , which confirmed that Cl- recirculation is dependent on the presence of GmSALT3 in shoots. Overall, these findings provide new insights on GmSALT3's impact on salinity tolerance and reveal a novel mechanism for shoot Cl- exclusion in plants.
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Affiliation(s)
- Yue Qu
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Glen Osmond, South Australia, Australia
| | - Rongxia Guan
- The National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jayakumar Bose
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Glen Osmond, South Australia, Australia
| | - Sam W Henderson
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Glen Osmond, South Australia, Australia
| | - Stefanie Wege
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Glen Osmond, South Australia, Australia
| | - Lijuan Qiu
- The National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Matthew Gilliham
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Glen Osmond, South Australia, Australia
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Alnayef M, Solis C, Shabala L, Ogura T, Chen Z, Bose J, Maathuis FJM, Venkataraman G, Tanoi K, Yu M, Zhou M, Horie T, Shabala S. Changes in Expression Level of OsHKT1;5 Alters Activity of Membrane Transporters Involved in K + and Ca 2+ Acquisition and Homeostasis in Salinized Rice Roots. Int J Mol Sci 2020; 21:E4882. [PMID: 32664377 PMCID: PMC7402344 DOI: 10.3390/ijms21144882] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 01/02/2023] Open
Abstract
In rice, the OsHKT1;5 gene has been reported to be a critical determinant of salt tolerance. This gene is harbored by the SKC1 locus, and its role was attributed to Na+ unloading from the xylem. No direct evidence, however, was provided in previous studies. Also, the reported function of SKC1 on the loading and delivery of K+ to the shoot remains to be explained. In this work, we used an electrophysiological approach to compare the kinetics of Na+ uptake by root xylem parenchyma cells using wild type (WT) and NIL(SKC1) plants. Our data showed that Na+ reabsorption was observed in WT, but not NIL(SKC1) plants, thus questioning the functional role of HKT1;5 as a transporter operating in the direct Na+ removal from the xylem. Instead, changes in the expression level of HKT1;5 altered the activity of membrane transporters involved in K+ and Ca2+ acquisition and homeostasis in the rice epidermis and stele, explaining the observed phenotype. We conclude that the role of HKT1;5 in plant salinity tolerance cannot be attributed to merely reducing Na+ concentration in the xylem sap but triggers a complex feedback regulation of activities of other transporters involved in the maintenance of plant ionic homeostasis and signaling under stress conditions.
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Affiliation(s)
- Mohammad Alnayef
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (M.A.); (C.S.); (L.S.); (T.O.); (J.B.); (M.Z.)
| | - Celymar Solis
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (M.A.); (C.S.); (L.S.); (T.O.); (J.B.); (M.Z.)
- School of Science and Health, Western Sydney University, Penrith, NSW 2751, Australia;
| | - Lana Shabala
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (M.A.); (C.S.); (L.S.); (T.O.); (J.B.); (M.Z.)
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China;
| | - Takaaki Ogura
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (M.A.); (C.S.); (L.S.); (T.O.); (J.B.); (M.Z.)
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan;
| | - Zhonghua Chen
- School of Science and Health, Western Sydney University, Penrith, NSW 2751, Australia;
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
| | - Jayakumar Bose
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (M.A.); (C.S.); (L.S.); (T.O.); (J.B.); (M.Z.)
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA 5064, Australia
| | | | - Gayatri Venkataraman
- Plant Molecular Biology Laboratory, M.S. Swaminathan Research Foundation, Chennai 600113, India;
| | - Keitaro Tanoi
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan;
| | - Min Yu
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China;
| | - Meixue Zhou
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (M.A.); (C.S.); (L.S.); (T.O.); (J.B.); (M.Z.)
| | - Tomoaki Horie
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Nagano 386-8567, Japan;
| | - Sergey Shabala
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (M.A.); (C.S.); (L.S.); (T.O.); (J.B.); (M.Z.)
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China;
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Pedersen O, Revsbech NP, Shabala S. Microsensors in plant biology: in vivo visualization of inorganic analytes with high spatial and/or temporal resolution. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3941-3954. [PMID: 32253437 DOI: 10.1093/jxb/eraa175] [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: 04/03/2020] [Accepted: 04/04/2020] [Indexed: 06/11/2023]
Abstract
This Expert View provides an update on the recent development of new microsensors, and briefly summarizes some novel applications of existing microsensors, in plant biology research. Two major topics are covered: (i) sensors for gaseous analytes (O2, CO2, and H2S); and (ii) those for measuring concentrations and fluxes of ions (macro- and micronutrients and environmental pollutants such as heavy metals). We show that application of such microsensors may significantly advance understanding of mechanisms of plant-environmental interaction and regulation of plant developmental and adaptive responses under adverse environmental conditions via non-destructive visualization of key analytes with high spatial and/or temporal resolution. Examples included cover a broad range of environmental situations including hypoxia, salinity, and heavy metal toxicity. We highlight the power of combining microsensor technology with other advanced biophysical (patch-clamp, voltage-clamp, and single-cell pressure probe), imaging (MRI and fluorescent dyes), and genetic techniques and approaches. We conclude that future progress in the field may be achieved by applying existing microsensors for important signalling molecules such as NO and H2O2, by improving selectivity of existing microsensors for some key analytes (e.g. Na, Mg, and Zn), and by developing new microsensors for P.
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Affiliation(s)
- Ole Pedersen
- Department of Biology, University of Copenhagen, Denmark
- School of Agriculture and Environment, The University of Western Australia, Australia
| | - Niels Peter Revsbech
- Aarhus University Centre for Water Technology, Department of Bioscience, Aarhus University, Denmark
| | - Sergey Shabala
- School of Land and Food, University of Tasmania, Australia
- International Research Centre for Environmental Membrane Biology, Foshan University, China
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Zarei M, Shabala S, Zeng F, Chen X, Zhang S, Azizi M, Rahemi M, Davarpanah S, Yu M, Shabala L. Comparing Kinetics of Xylem Ion Loading and Its Regulation in Halophytes and Glycophytes. PLANT & CELL PHYSIOLOGY 2020; 61:403-415. [PMID: 31693150 DOI: 10.1093/pcp/pcz205] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 10/29/2019] [Indexed: 05/02/2023]
Abstract
Although control of xylem ion loading is essential to confer salinity stress tolerance, specific details behind this process remain elusive. In this work, we compared the kinetics of xylem Na+ and K+ loading between two halophytes (Atriplex lentiformis and quinoa) and two glycophyte (pea and beans) species, to understand the mechanistic basis of the above process. Halophyte plants had high initial amounts of Na+ in the leaf, even when grown in the absence of the salt stress. This was matched by 7-fold higher xylem sap Na+ concentration compared with glycophyte plants. Upon salinity exposure, the xylem sap Na+ concentration increased rapidly but transiently in halophytes, while in glycophytes this increase was much delayed. Electrophysiological experiments using the microelectrode ion flux measuring technique showed that glycophyte plants tend to re-absorb Na+ back into the stele, thus reducing xylem Na+ load at the early stages of salinity exposure. The halophyte plants, however, were capable to release Na+ even in the presence of high Na+ concentrations in the xylem. The presence of hydrogen peroxide (H2O2) [mimicking NaCl stress-induced reactive oxygen species (ROS) accumulation in the root] caused a massive Na+ and Ca2+ uptake into the root stele, while triggering a substantial K+ efflux from the cytosol into apoplast in glycophyte but not halophytes species. The peak in H2O2 production was achieved faster in halophytes (30 min vs 4 h) and was attributed to the increased transcript levels of RbohE. Pharmacological data suggested that non-selective cation channels are unlikely to play a major role in ROS-mediated xylem Na+ loading.
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Affiliation(s)
- Mahvash Zarei
- Department of Horticultural Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Sergey Shabala
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, TAS, Australia
| | - Fanrong Zeng
- Agronomy Department, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
| | - Xiaohui Chen
- Agronomy Department, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
| | - Shuo Zhang
- Agronomy Department, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
| | - Majid Azizi
- Department of Horticultural Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Majid Rahemi
- Department of Horticultural Science, Faculty of Agriculture, Shiraz University, Shiraz, Iran
| | - Sohrab Davarpanah
- Department of Horticultural Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Min Yu
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China
| | - Lana Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, TAS, Australia
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Morris C, O'Donnell M. Multiple functions of ion transport by the nuchal organ in embryos and neonates of the freshwater branchiopod crustacean Daphnia magna. ACTA ACUST UNITED AC 2019; 222:jeb.211128. [PMID: 31645374 DOI: 10.1242/jeb.211128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/18/2019] [Indexed: 01/07/2023]
Abstract
The nuchal organ, also referred to as the dorsal organ or neck organ, is a dorsal structure located posteriorly to the compound eye, between the bases of the second antennae of embryonic and neonate branchiopod crustaceans such as the water flea, Daphnia magna The ultrastructure of the nuchal organ is similar to ion-transporting tissues in other crustaceans, including abundant mitochondria and extensive amplification of apical and basal plasma membranes through microvilli and infoldings, but direct evidence for ion transport is lacking. We used the scanning ion-selective electrode technique to measure transport of Na+, K+, H+, Cl-, NH4 + and Ca2+ across the nuchal organ and body surface of embryos and neonates bathed in dechlorinated Hamilton tap water. Influx of Na+ and efflux of H+ and NH4 + was found to occur across the nuchal organ of both embryos and neonates. We propose that the efflux of K+ and Cl- across the nuchal organ in embryos is related to the expansion of the haemocoel and release of intracellular solutes into the extracellular space during development. K+ is taken up across the nuchal organ later during development, coincident with expansion of the intracellular compartment through the development of gills and other organs. Ca2+ influx across the nuchal organ and body surface of neonates but not embryos is presumably related to calcification of the exoskeleton. Increases in the levels of Na+ and Ca2+ in the water within the brood chamber suggest maternal provisioning of ions for uptake by the embryos. Our data thus support roles for the nuchal organ in ionoregulation, pH regulation and nitrogenous waste excretion.
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Affiliation(s)
- Carolyn Morris
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - Michael O'Donnell
- Department of Biology, McMaster University, Hamilton, ON, Canada L8S 4K1
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Wu H, Shabala L, Zhou M, Su N, Wu Q, Ul-Haq T, Zhu J, Mancuso S, Azzarello E, Shabala S. Root vacuolar Na + sequestration but not exclusion from uptake correlates with barley salt tolerance. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 100:55-67. [PMID: 31148333 DOI: 10.1111/tpj.14424] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 05/16/2019] [Accepted: 05/21/2019] [Indexed: 05/24/2023]
Abstract
Soil salinity is a major constraint for the global agricultural production. For many decades, Na+ exclusion from uptake has been the key trait targeted in breeding programs; yet, no major breakthrough in creating salt-tolerant germplasm was achieved. In this work, we have combined the microelectrode ion flux estimation (MIFE) technique for non-invasive ion flux measurements with confocal fluorescence dye imaging technique to screen 45 accessions of barley to reveal the relative contribution of Na+ exclusion from the cytosol to the apoplast and its vacuolar sequestration in the root apex, for the overall salinity stress tolerance. We show that Na+ /H+ antiporter-mediated Na+ extrusion from the root plays a minor role in the overall salt tolerance in barley. At the same time, a strong and positive correlation was found between root vacuolar Na+ sequestration ability and the overall salt tolerance. The inability of salt-sensitive genotypes to sequester Na+ in root vacuoles was in contrast to significantly higher expression levels of both HvNHX1 tonoplast Na+ /H+ antiporters and HvVP1 H+ -pumps compared with tolerant genotypes. These data are interpreted as a failure of sensitive varieties to prevent Na+ back-leak into the cytosol and existence of a futile Na+ cycle at the tonoplast. Taken together, our results demonstrated that root vacuolar Na+ sequestration but not exclusion from uptake played the main role in barley salinity tolerance, and suggested that the focus of the breeding programs should be shifted from targeting genes mediating Na+ exclusion from uptake by roots to more efficient root vacuolar Na+ sequestration.
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Affiliation(s)
- Honghong Wu
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania, 7001, Australia
- College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Lana Shabala
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania, 7001, Australia
| | - Meixue Zhou
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania, 7001, Australia
| | - Nana Su
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania, 7001, Australia
| | - Qi Wu
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania, 7001, Australia
| | - Tanveer Ul-Haq
- Department of Soil and Environmental Sciences, MNS University of Agriculture, Multan, 60000, Pakistan
| | - Juan Zhu
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania, 7001, Australia
| | - Stefano Mancuso
- Department of Horticulture, University of Florence, 50019, Sesto Fiorentino, Italy
| | - Elisa Azzarello
- Department of Horticulture, University of Florence, 50019, Sesto Fiorentino, Italy
| | - Sergey Shabala
- Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania, 7001, Australia
- International Centre for Environmental Membrane Biology, Foshan University, Foshan, China
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Zeng F, Shabala S, Maksimović JD, Maksimović V, Bonales-Alatorre E, Shabala L, Yu M, Zhang G, Živanović BD. Revealing mechanisms of salinity tissue tolerance in succulent halophytes: A case study for Carpobrotus rossi. PLANT, CELL & ENVIRONMENT 2018; 41:2654-2667. [PMID: 29956332 DOI: 10.1111/pce.13391] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 06/08/2023]
Abstract
Efforts to breed salt tolerant crops could benefit from investigating previously unexplored traits. One of them is a tissue succulency. In this work, we have undertaken an electrophysiological and biochemical comparison of properties of mesophyll and storage parenchyma leaf tissues of a succulent halophyte species Carpobrotus rosii ("pigface"). We show that storage parenchyma cells of C. rossii act as Na+ sink and possessed both higher Na+ sequestration (298 vs. 215 mM NaCl in mesophyll) and better K+ retention ability. The latter traits was determined by the higher rate of H+ -ATPase operation and higher nonenzymatic antioxidant activity in this tissue. Na+ uptake in both tissues was insensitive to either Gd3+ or elevated Ca2+ ruling out involvement of nonselective cation channels as a major path for Na+ entry. Patch-clamp experiments have revealed that Caprobrotus plants were capable to downregulate activity of fast vacuolar channels when exposed to saline environment; this ability was higher in the storage parenchyma cells compared with mesophyll. Also, storage parenchyma cells have constitutively lower number of open slow vacuolar channels, whereas in mesophyll, this suppression was inducible by salt. Taken together, these results provide a mechanistic basis for efficient Na+ sequestration in the succulent leaf tissues.
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Affiliation(s)
- Fanrong Zeng
- Department of Agronomy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
- College of Science and Engineering, University of Tasmania, Hobart, TAS, Australia
| | - Sergey Shabala
- Department of Horticulture, Foshan University, Foshan, China
- College of Science and Engineering, University of Tasmania, Hobart, TAS, Australia
| | | | - Vuk Maksimović
- Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia
| | - Edgar Bonales-Alatorre
- College of Science and Engineering, University of Tasmania, Hobart, TAS, Australia
- Centro Universitario de Investigaciones Biomédicas, University of Colima, Colima, México
| | - Lana Shabala
- College of Science and Engineering, University of Tasmania, Hobart, TAS, Australia
| | - Min Yu
- Department of Horticulture, Foshan University, Foshan, China
| | - Guoping Zhang
- Department of Agronomy, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China
| | - Branka D Živanović
- Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia
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Niu M, Xie J, Chen C, Cao H, Sun J, Kong Q, Shabala S, Shabala L, Huang Y, Bie Z. An early ABA-induced stomatal closure, Na+ sequestration in leaf vein and K+ retention in mesophyll confer salt tissue tolerance in Cucurbita species. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:4945-4960. [PMID: 29992291 PMCID: PMC6137988 DOI: 10.1093/jxb/ery251] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 06/29/2018] [Indexed: 05/20/2023]
Abstract
Tissue tolerance to salinity stress is a complex physiological trait composed of multiple 'sub-traits' such as Na+ compartmentalization, K+ retention, and osmotic tolerance. Previous studies have shown that some Cucurbita species employ tissue tolerance to combat salinity and we aimed to identify the physiological and molecular mechanisms involved. Five C. maxima (salt-tolerant) and five C. moschata (salt-sensitive) genotypes were comprehensively assessed for their salt tolerance mechanisms and the results showed that tissue-specific transport characteristics enabled the more tolerant lines to deal with the salt load. This mechanism was associated with the ability of the tolerant species to accumulate more Na+ in the leaf vein and to retain more K+ in the leaf mesophyll. In addition, C. maxima more efficiently retained K+ in the roots when exposed to transient NaCl stress and it was also able to store more Na+ in the xylem parenchyma and cortex in the leaf vein. Compared with C. moschata, C. maxima was also able to rapidly close stomata at early stages of salt stress, thus avoiding water loss; this difference was attributed to higher accumulation of ABA in the leaf. Transcriptome and qRT-PCR analyses revealed critical roles of high-affinity potassium (HKT1) and intracellular Na+/H+ (NHX4/6) transporters as components of the mechanism enabling Na+ exclusion from the leaf mesophyll and Na+ sequestration in the leaf vein. Also essential was a higher expression of NCED3s (encoding 9-cis-epoxycarotenoid dioxygenase, a key rate-limiting enzyme in ABA biosynthesis), which resulted in greater ABA accumulation in the mesophyll and earlier stomata closure in C. maxima.
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Affiliation(s)
- Mengliang Niu
- College of Horticulture and Forestry Sciences, Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, P. R. China
| | - Junjun Xie
- College of Horticulture and Forestry Sciences, Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, P. R. China
| | - Chen Chen
- College of Horticulture and Forestry Sciences, Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, P. R. China
| | - Haishun Cao
- College of Horticulture and Forestry Sciences, Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, P. R. China
| | - Jingyu Sun
- College of Horticulture and Forestry Sciences, Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, P. R. China
| | - Qiusheng Kong
- College of Horticulture and Forestry Sciences, Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, P. R. China
| | - Sergey Shabala
- Department of Horticulture, Foshan University, Foshan, P. R. China
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tasmania, Australia
| | - Lana Shabala
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tasmania, Australia
| | - Yuan Huang
- College of Horticulture and Forestry Sciences, Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, P. R. China
- Tasmanian Institute for Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tasmania, Australia
| | - Zhilong Bie
- College of Horticulture and Forestry Sciences, Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, P. R. China
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10
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Wu H, Shabala L, Azzarello E, Huang Y, Pandolfi C, Su N, Wu Q, Cai S, Bazihizina N, Wang L, Zhou M, Mancuso S, Chen Z, Shabala S. Na+ extrusion from the cytosol and tissue-specific Na+ sequestration in roots confer differential salt stress tolerance between durum and bread wheat. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:3987-4001. [PMID: 29897491 PMCID: PMC6054258 DOI: 10.1093/jxb/ery194] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 05/21/2018] [Indexed: 05/25/2023]
Abstract
The progress in plant breeding for salinity stress tolerance is handicapped by the lack of understanding of the specificity of salt stress signalling and adaptation at the cellular and tissue levels. In this study, we used electrophysiological, fluorescence imaging, and real-time quantitative PCR tools to elucidate the essentiality of the cytosolic Na+ extrusion in functionally different root zones (elongation, meristem, and mature) in a large number of bread and durum wheat accessions. We show that the difference in the root's ability for vacuolar Na+ sequestration in the mature zone may explain differential salinity stress tolerance between salt-sensitive durum and salt-tolerant bread wheat species. Bread wheat genotypes also had on average 30% higher capacity for net Na+ efflux from the root elongation zone, providing the first direct evidence for the essentiality of the root salt exclusion trait at the cellular level. At the same time, cytosolic Na+ accumulation in the root meristem was significantly higher in bread wheat, leading to the suggestion that this tissue may harbour a putative salt sensor. This hypothesis was then tested by investigating patterns of Na+ distribution and the relative expression level of several key genes related to Na+ transport in leaves in plants with intact roots and in those in which the root meristems were removed. We show that tampering with this sensing mechanism has resulted in a salt-sensitive phenotype, largely due to compromising the plant's ability to sequester Na+ in mesophyll cell vacuoles. The implications of these findings for plant breeding for salinity stress tolerance are discussed.
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Affiliation(s)
- Honghong Wu
- School of Land and Food, University of Tasmania, Private Bag, Hobart, Tasmania, Australia
| | - Lana Shabala
- School of Land and Food, University of Tasmania, Private Bag, Hobart, Tasmania, Australia
| | - Elisa Azzarello
- Department of Horticulture, University of Florence, Sesto Fiorentino, Italy
| | - Yuqing Huang
- School of Science and Health, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Camilla Pandolfi
- Department of Horticulture, University of Florence, Sesto Fiorentino, Italy
| | - Nana Su
- School of Land and Food, University of Tasmania, Private Bag, Hobart, Tasmania, Australia
| | - Qi Wu
- School of Land and Food, University of Tasmania, Private Bag, Hobart, Tasmania, Australia
| | - Shengguan Cai
- School of Science and Health, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Nadia Bazihizina
- School of Land and Food, University of Tasmania, Private Bag, Hobart, Tasmania, Australia
- Department of Horticulture, University of Florence, Sesto Fiorentino, Italy
| | - Lu Wang
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, Australia
| | - Meixue Zhou
- School of Land and Food, University of Tasmania, Private Bag, Hobart, Tasmania, Australia
| | - Stefano Mancuso
- Department of Horticulture, University of Florence, Sesto Fiorentino, Italy
| | - Zhonghua Chen
- School of Science and Health, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Sergey Shabala
- School of Land and Food, University of Tasmania, Private Bag, Hobart, Tasmania, Australia
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11
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Byrt CS, Zhao M, Kourghi M, Bose J, Henderson SW, Qiu J, Gilliham M, Schultz C, Schwarz M, Ramesh SA, Yool A, Tyerman S. Non-selective cation channel activity of aquaporin AtPIP2;1 regulated by Ca 2+ and pH. PLANT, CELL & ENVIRONMENT 2017; 40:802-815. [PMID: 27620834 DOI: 10.1111/pce.12832] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 09/08/2016] [Accepted: 09/10/2016] [Indexed: 05/20/2023]
Abstract
The aquaporin AtPIP2;1 is an abundant plasma membrane intrinsic protein in Arabidopsis thaliana that is implicated in stomatal closure, and is highly expressed in plasma membranes of root epidermal cells. When expressed in Xenopus laevis oocytes, AtPIP2;1 increased water permeability and induced a non-selective cation conductance mainly associated with Na+ . A mutation in the water pore, G103W, prevented both the ionic conductance and water permeability of PIP2;1. Co-expression of AtPIP2;1 with AtPIP1;2 increased water permeability but abolished the ionic conductance. AtPIP2;2 (93% identical to AtPIP2;1) similarly increased water permeability but not ionic conductance. The ionic conductance was inhibited by the application of extracellular Ca2+ and Cd2+ , with Ca2+ giving a biphasic dose-response with a prominent IC50 of 0.32 mм comparable with a previous report of Ca2+ sensitivity of a non-selective cation channel (NSCC) in Arabidopsis root protoplasts. Low external pH also inhibited ionic conductance (IC50 pH 6.8). Xenopus oocytes and Saccharomyces cerevisiae expressing AtPIP2;1 accumulated more Na+ than controls. Establishing whether AtPIP2;1 has dual ion and water permeability in planta will be important in understanding the roles of this aquaporin and if AtPIP2;1 is a candidate for a previously reported NSCC responsible for Ca2+ and pH sensitive Na+ entry into roots.
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Affiliation(s)
- Caitlin S Byrt
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
| | - Manchun Zhao
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
| | - Mohamad Kourghi
- Discipline of Physiology, School of Medicine, University of Adelaide, South Australia, 5005, Australia
| | - Jayakumar Bose
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
| | - Sam W Henderson
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
| | - Jiaen Qiu
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
| | - Matthew Gilliham
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
| | - Carolyn Schultz
- Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
| | - Manuel Schwarz
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
| | - Sunita A Ramesh
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
| | - Andrea Yool
- Discipline of Physiology, School of Medicine, University of Adelaide, South Australia, 5005, Australia
| | - Steve Tyerman
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, South Australia, 5064, Australia
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12
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Böhm J, Scherzer S, Shabala S, Krol E, Neher E, Mueller TD, Hedrich R. Venus Flytrap HKT1-Type Channel Provides for Prey Sodium Uptake into Carnivorous Plant Without Conflicting with Electrical Excitability. MOLECULAR PLANT 2016; 9:428-436. [PMID: 26455461 PMCID: PMC4791408 DOI: 10.1016/j.molp.2015.09.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/24/2015] [Accepted: 09/24/2015] [Indexed: 05/05/2023]
Abstract
The animal diet of the carnivorous Venus flytrap, Dionaea muscipula, contains a sodium load that enters the capture organ via an HKT1-type sodium channel, expressed in special epithelia cells on the inner trap lobe surface. DmHKT1 expression and sodium uptake activity is induced upon prey contact. Here, we analyzed the HKT1 properties required for prey sodium osmolyte management of carnivorous Dionaea. Analyses were based on homology modeling, generation of model-derived point mutants, and their functional testing in Xenopus oocytes. We showed that the wild-type HKT1 and its Na(+)- and K(+)-permeable mutants function as ion channels rather than K(+) transporters driven by proton or sodium gradients. These structural and biophysical features of a high-capacity, Na(+)-selective ion channel enable Dionaea glands to manage prey-derived sodium loads without confounding the action potential-based information management of the flytrap.
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Affiliation(s)
- J Böhm
- Julius-von-Sachs Institute, Department for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - S Scherzer
- Julius-von-Sachs Institute, Department for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - S Shabala
- School of Land and Food, University of Tasmania, Hobart TAS 7001, Australia
| | - E Krol
- Julius-von-Sachs Institute, Department for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - E Neher
- Zoology Department, College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia; Department for Membrane Biophysics, Max Planck Institute for Biophysical Chemistry, 37077 Goettingen, Germany
| | - T D Mueller
- Julius-von-Sachs Institute, Department for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany.
| | - R Hedrich
- Julius-von-Sachs Institute, Department for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany.
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13
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Böhm J, Scherzer S, Krol E, Kreuzer I, von Meyer K, Lorey C, Mueller TD, Shabala L, Monte I, Solano R, Al-Rasheid KAS, Rennenberg H, Shabala S, Neher E, Hedrich R. The Venus Flytrap Dionaea muscipula Counts Prey-Induced Action Potentials to Induce Sodium Uptake. Curr Biol 2016; 26:286-95. [PMID: 26804557 PMCID: PMC4751343 DOI: 10.1016/j.cub.2015.11.057] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 10/23/2015] [Accepted: 11/26/2015] [Indexed: 01/05/2023]
Abstract
Carnivorous plants, such as the Venus flytrap (Dionaea muscipula), depend on an animal diet when grown in nutrient-poor soils. When an insect visits the trap and tilts the mechanosensors on the inner surface, action potentials (APs) are fired. After a moving object elicits two APs, the trap snaps shut, encaging the victim. Panicking preys repeatedly touch the trigger hairs over the subsequent hours, leading to a hermetically closed trap, which via the gland-based endocrine system is flooded by a prey-decomposing acidic enzyme cocktail. Here, we asked the question as to how many times trigger hairs have to be stimulated (e.g., now many APs are required) for the flytrap to recognize an encaged object as potential food, thus making it worthwhile activating the glands. By applying a series of trigger-hair stimulations, we found that the touch hormone jasmonic acid (JA) signaling pathway is activated after the second stimulus, while more than three APs are required to trigger an expression of genes encoding prey-degrading hydrolases, and that this expression is proportional to the number of mechanical stimulations. A decomposing animal contains a sodium load, and we have found that these sodium ions enter the capture organ via glands. We identified a flytrap sodium channel DmHKT1 as responsible for this sodium acquisition, with the number of transcripts expressed being dependent on the number of mechano-electric stimulations. Hence, the number of APs a victim triggers while trying to break out of the trap identifies the moving prey as a struggling Na+-rich animal and nutrition for the plant. Video Abstract
Carnivorous Dionaea muscipula captures and processes nutrient- and sodium-rich prey Via mechano-sensor stimulation, an animal meal is recognized, captured, and processed Mechano-electrical waves induce JA signaling pathways that trigger prey digestion Number of stimulations controls the production of digesting enzymes and uptake modules
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Affiliation(s)
- Jennifer Böhm
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Sönke Scherzer
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Elzbieta Krol
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Ines Kreuzer
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Katharina von Meyer
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Christian Lorey
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany; Naturwissenschaftliches Labor für Schüler, Friedrich-Koenig-Gymnasium, 97082 Würzburg, Germany
| | - Thomas D Mueller
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Lana Shabala
- School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia
| | - Isabel Monte
- Plant Molecular Genetics Department, National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), Campus University Autónoma, 28049 Madrid, Spain
| | - Roberto Solano
- Plant Molecular Genetics Department, National Centre for Biotechnology (CNB), Consejo Superior de Investigaciones Científicas (CSIC), Campus University Autónoma, 28049 Madrid, Spain
| | - Khaled A S Al-Rasheid
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany; Zoology Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Heinz Rennenberg
- Institute of Forest Sciences, University of Freiburg, Georges-Koehler-Allee 53/54, 79085 Freiburg, Germany
| | - Sergey Shabala
- School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia
| | - Erwin Neher
- Department for Membrane Biophysics, Max Planck Institute for Biophysical Chemistry, 37077 Goettingen, Germany.
| | - Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany.
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14
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Schellinger JN, Rodan AR. Use of the Ramsay Assay to Measure Fluid Secretion and Ion Flux Rates in the Drosophila melanogaster Malpighian Tubule. J Vis Exp 2015. [PMID: 26650886 DOI: 10.3791/53144] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Modulation of renal epithelial ion transport allows organisms to maintain ionic and osmotic homeostasis in the face of varying external conditions. The Drosophila melanogaster Malpighian (renal) tubule offers an unparalleled opportunity to study the molecular mechanisms of epithelial ion transport, due to the powerful genetics of this organism and the accessibility of its renal tubules to physiological study. Here, we describe the use of the Ramsay assay to measure fluid secretion rates from isolated fly renal tubules, with the use of ion-specific electrodes to measure sodium and potassium concentrations in the secreted fluid. This assay allows study of transepithelial fluid and ion fluxes of ~20 tubules at a time, without the need to transfer the secreted fluid to a separate apparatus to measure ion concentrations. Genetically distinct tubules can be analyzed to assess the role of specific genes in transport processes. Additionally, the bathing saline can be modified to examine the effects of its chemical characteristics, or drugs or hormones added. In summary, this technique allows the molecular characterization of basic mechanisms of epithelial ion transport in the Drosophila tubule, as well as regulation of these transport mechanisms.
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Affiliation(s)
| | - Aylin R Rodan
- Department of Internal Medicine, University of Texas Southwestern Medical Center;
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15
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O'Donnell MJ, Ruiz-Sanchez E. The rectal complex and Malpighian tubules of the cabbage looper (Trichoplusia ni): regional variations in Na+ and K+ transport and cation reabsorption by secondary cells. J Exp Biol 2015; 218:3206-14. [PMID: 26491192 DOI: 10.1242/jeb.128314] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
ABSTRACT
In larvae of most Lepidoptera the distal ends of the Malpighian tubules are closely applied to the rectal epithelia and are ensheathed within the perinephric membrane, thus forming the rectal complex. The cryptonephric Malpighian tubules within the rectal complex are bathed in fluid within a functional compartment, the perinephric space, which is separate from the haemolymph. In this study, the scanning ion-selective electrode technique (SIET) was used to measure transport of Na+ and K+ across the rectal complex and across multiple regions of the Malpighian tubules of larvae of the cabbage looper Trichoplusia ni. Measurements were made in an intact preparation in which connections of the tubules upstream to the rectal complex and downstream to the urinary bladder and gut remained intact. SIET measurements revealed reabsorption of Na+ and K+ across the intact rectal complex and into the bath (haemolymph), with K+ fluxes approximately twice as large as those of Na+. Analyses of fluxes in larvae with empty guts, found in recently moulted larvae, versus those with full guts highlighted differences in the rates of K+ or Na+ transport within tubule regions that appeared morphologically homogeneous, such as the rectal lead. The distal rectal lead of larvae with empty guts reabsorbed K+, whereas the same region secreted K+ in tubules of larvae with full guts. SIET measurements of the ileac plexus also indicated a novel role for secondary (type II) cells in cation reabsorption. Secondary cells reabsorb K+, whereas the adjacent principal (type I) cells secrete K+. Na+ is reabsorbed by both principal and secondary cells, but the rate of reabsorption by the secondary cells is approximately twice the rate in the adjacent principal cells.
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Affiliation(s)
- Michael J. O'Donnell
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1
| | - Esau Ruiz-Sanchez
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1
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16
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Britto DT, Kronzucker HJ. Sodium efflux in plant roots: what do we really know? JOURNAL OF PLANT PHYSIOLOGY 2015; 186-187:1-12. [PMID: 26318642 DOI: 10.1016/j.jplph.2015.08.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 08/03/2015] [Accepted: 08/03/2015] [Indexed: 05/27/2023]
Abstract
The efflux of sodium (Na(+)) ions across the plasma membrane of plant root cells into the external medium is surprisingly poorly understood. Nevertheless, Na(+) efflux is widely regarded as a major mechanism by which plants restrain the rise of Na(+) concentrations in the cytosolic compartments of root cells and, thus, achieve a degree of tolerance to saline environments. In this review, several key ideas and bodies of evidence concerning root Na(+) efflux are summarized with a critical eye. Findings from decades past are brought to bear on current thinking, and pivotal studies are discussed, both "purely physiological", and also with regard to the SOS1 protein, the only major Na(+) efflux transporter that has, to date, been genetically characterized. We find that the current model of rapid transmembrane sodium cycling (RTSC), across the plasma membrane of root cells, is not adequately supported by evidence from the majority of efflux studies. An alternative hypothesis cannot be ruled out, that most Na(+) tracer efflux from the root in the salinity range does not proceed across the plasma membrane, but through the apoplast. Support for this idea comes from studies showing that Na(+) efflux, when measured with tracers, is rarely affected by the presence of inhibitors or the ionic composition in saline rooting media. We conclude that the actual efflux of Na(+) across the plasma membrane of root cells may be much more modest than what is often reported in studies using tracers, and may predominantly occur in the root tips, where SOS1 expression has been localized.
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Affiliation(s)
- D T Britto
- University of Toronto, Canadian Centre for World Hunger Research, Canada
| | - H J Kronzucker
- University of Toronto, Canadian Centre for World Hunger Research, Canada.
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17
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Muralidhar A, Shabala L, Broady P, Shabala S, Garrill A. Mechanisms underlying turgor regulation in the estuarine alga Vaucheria erythrospora (Xanthophyceae) exposed to hyperosmotic shock. PLANT, CELL & ENVIRONMENT 2015; 38:1514-1527. [PMID: 25546818 DOI: 10.1111/pce.12503] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 12/07/2014] [Accepted: 12/11/2014] [Indexed: 06/04/2023]
Abstract
Aquatic organisms are often exposed to dramatic changes in salinity in the environment. Despite decades of research, many questions related to molecular and physiological mechanisms mediating sensing and adaptation to salinity stress remain unanswered. Here, responses of Vaucheria erythrospora, a turgor-regulating xanthophycean alga from an estuarine habitat, have been investigated. The role of ion uptake in turgor regulation was studied using a single cell pressure probe, microelectrode ion flux estimation (MIFE) technique and membrane potential (Em ) measurements. Turgor recovery was inhibited by Gd(3+) , tetraethylammonium chloride (TEA), verapamil and orthovanadate. A NaCl-induced shock rapidly depolarized the plasma membrane while an isotonic sorbitol treatment hyperpolarized it. Turgor recovery was critically dependent on the presence of Na(+) but not K(+) and Cl(-) in the incubation media. Na(+) uptake was strongly decreased by amiloride and changes in net Na(+) and H(+) fluxes were oppositely directed. This suggests active uptake of Na(+) in V. erythrospora mediated by an antiport Na(+) /H(+) system, functioning in the direction opposite to that of the SOS1 exchanger in higher plants. The alga also retains K(+) efficiently when exposed to high NaCl concentrations. Overall, this study provides insights into mechanisms enabling V. erythrospora to regulate turgor via ion movements during hyperosmotic stress.
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Affiliation(s)
- Abishek Muralidhar
- School of Biological Sciences, University of Canterbury, Christchurch, 8011, New Zealand
| | - Lana Shabala
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Paul Broady
- School of Biological Sciences, University of Canterbury, Christchurch, 8011, New Zealand
| | - Sergey Shabala
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Ashley Garrill
- School of Biological Sciences, University of Canterbury, Christchurch, 8011, New Zealand
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18
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Jayakannan M, Bose J, Babourina O, Shabala S, Massart A, Poschenrieder C, Rengel Z. The NPR1-dependent salicylic acid signalling pathway is pivotal for enhanced salt and oxidative stress tolerance in Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:1865-75. [PMID: 25614660 PMCID: PMC4378626 DOI: 10.1093/jxb/eru528] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The role of endogenous salicylic acid (SA) signalling cascades in plant responses to salt and oxidative stresses is unclear. Arabidopsis SA signalling mutants, namely npr1-5 (non-expresser of pathogenesis related gene1), which lacks NPR1-dependent SA signalling, and nudt7 (nudix hydrolase7), which has both constitutively expressed NPR1-dependent and NPR1-independent SA signalling pathways, were compared with the wild type (Col-0) during salt or oxidative stresses. Growth and viability staining showed that, compared with wild type, the npr1-5 mutant was sensitive to either salt or oxidative stress, whereas the nudt7 mutant was tolerant. Acute salt stress caused the strongest membrane potential depolarization, highest sodium and proton influx, and potassium loss from npr1-5 roots in comparison with the wild type and nudt7 mutant. Though salt stress-induced hydrogen peroxide production was lowest in the npr1-5 mutant, the reactive oxygen species (ROS) stress (induced by 1mM of hydroxyl-radical-generating copper-ascorbate mix, or either 1 or 10mM hydrogen peroxide) caused a higher potassium loss from the roots of the npr1-5 mutant than the wild type and nudt7 mutant. Long-term salt exposure resulted in the highest sodium and the lowest potassium concentration in the shoots of npr1-5 mutant in comparison with the wild type and nudt7 mutant. The above results demonstrate that NPR1-dependent SA signalling is pivotal to (i) controlling Na(+) entry into the root tissue and its subsequent long-distance transport into the shoot, and (ii) preventing a potassium loss through depolarization-activated outward-rectifying potassium and ROS-activated non-selective cation channels. In conclusion, NPR1-dependent SA signalling is central to the salt and oxidative stress tolerance in Arabidopsis.
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Affiliation(s)
- Maheswari Jayakannan
- School of Earth and Environment, Faculty of Science, University of Western Australia, Crawley WA 6009, Australia School of Land and Food, University of Tasmania, Hobart TAS 7001, Australia School of Biological Sciences, University of Tasmania, Hobart TAS 7001, Australia
| | - Jayakumar Bose
- School of Land and Food, University of Tasmania, Hobart TAS 7001, Australia
| | - Olga Babourina
- School of Earth and Environment, Faculty of Science, University of Western Australia, Crawley WA 6009, Australia
| | - Sergey Shabala
- School of Land and Food, University of Tasmania, Hobart TAS 7001, Australia
| | - Amandine Massart
- Fisiología Vegetal, Facultad de Biociencias, Universidad Autónoma de Barcelona, E-08193 Bellaterra, Spain Environmental Science and Engineering Section, Ecole Polytechnique Fédérale de Lausanne, CH 1015 Lausanne, Switzerland
| | | | - Zed Rengel
- School of Earth and Environment, Faculty of Science, University of Western Australia, Crawley WA 6009, Australia
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19
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Ismail H, Dragišic Maksimovic J, Maksimovic V, Shabala L, Živanovic BD, Tian Y, Jacobsen SE, Shabala S. Rutin, a flavonoid with antioxidant activity, improves plant salinity tolerance by regulating K + retention and Na + exclusion from leaf mesophyll in quinoa and broad beans. FUNCTIONAL PLANT BIOLOGY : FPB 2015; 43:75-86. [PMID: 32480443 DOI: 10.1071/fp15312] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 11/01/2015] [Indexed: 05/20/2023]
Abstract
The causal relationship between salinity and oxidative stress tolerance is well established, but specific downstream targets and the role of specific antioxidant compounds in controlling cellular ionic homeostasis remains elusive. In this work, we have compared antioxidant profiles of leaves of two quinoa genotypes contrasting in their salt tolerance, with the aim of understanding the role of enzymatic and non-enzymatic antioxidants in salinity stress tolerance. Only changes in superoxide dismutase activity were correlated with plant adaptive responses to salinity. Proline accumulation played no major role in either osmotic adjustment or in the tissue tolerance mechanism. Among other non-enzymatic antioxidants, rutin levels were increased by over 25 fold in quinoa leaves. Exogenous application of rutin to glycophyte bean leaves improved tissue tolerance and reduced detrimental effects of salinity on leaf photochemistry. Electrophysiological experiments revealed that these beneficial effects were attributed to improved potassium retention and increased rate of Na+ pumping from the cell. The lack of correlation between rutin-induced changes in K+ and H+ fluxes suggest that rutin accumulation in the cytosol scavenges hydroxyl radical formed in response to salinity treatment thus preventing K+ leak via one of ROS-activated K+ efflux pathways, rather than controlling K+ flux via voltage-gated K+-permeable channels.
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Affiliation(s)
- Hebatollah Ismail
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, Tas. 7001, Australia
| | - Jelena Dragišic Maksimovic
- Institute for Multidisciplinary Studies, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia
| | - Vuk Maksimovic
- Institute for Multidisciplinary Studies, University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia
| | - Lana Shabala
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, Tas. 7001, Australia
| | - Branka D Živanovic
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, Tas. 7001, Australia
| | - Yu Tian
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, Tas. 7001, Australia
| | - Sven-Erik Jacobsen
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, Tas. 7001, Australia
| | - Sergey Shabala
- School of Land and Food and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, Tas. 7001, Australia
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Bose J, Rodrigo-Moreno A, Lai D, Xie Y, Shen W, Shabala S. Rapid regulation of the plasma membrane H⁺-ATPase activity is essential to salinity tolerance in two halophyte species, Atriplex lentiformis and Chenopodium quinoa. ANNALS OF BOTANY 2015; 115:481-94. [PMID: 25471095 PMCID: PMC4332608 DOI: 10.1093/aob/mcu219] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS The activity of H(+)-ATPase is essential for energizing the plasma membrane. It provides the driving force for potassium retention and uptake through voltage-gated channels and for Na(+) exclusion via Na(+)/H(+) exchangers. Both of these traits are central to plant salinity tolerance; however, whether the increased activity of H(+)-ATPase is a constitutive trait in halophyte species and whether this activity is upregulated at either the transcriptional or post-translation level remain disputed. METHODS The kinetics of salt-induced net H(+), Na(+) and K(+) fluxes, membrane potential and AHA1/2/3 expression changes in the roots of two halophyte species, Atriplex lentiformis (saltbush) and Chenopodium quinoa (quinoa), were compared with data obtained from Arabidopsis thaliana roots. KEY RESULTS Intrinsic (steady-state) membrane potential values were more negative in A. lentiformis and C. quinoa compared with arabidopsis (-144 ± 3·3, -138 ± 5·4 and -128 ± 3·3 mV, respectively). Treatment with 100 mm NaCl depolarized the root plasma membrane, an effect that was much stronger in arabidopsis. The extent of plasma membrane depolarization positively correlated with NaCl-induced stimulation of vanadate-sensitive H(+) efflux, Na(+) efflux and K(+) retention in roots (quinoa > saltbush > arabidopsis). NaCl-induced stimulation of H(+) efflux was most pronounced in the root elongation zone. In contrast, H(+)-ATPase AHA transcript levels were much higher in arabidopsis compared with quinoa plants, and 100 mm NaCl treatment led to a further 3-fold increase in AHA1 and AHA2 transcripts in arabidopsis but not in quinoa. CONCLUSIONS Enhanced salinity tolerance in the halophyte species studied here is not related to the constitutively higher AHA transcript levels in the root epidermis, but to the plant's ability to rapidly upregulate plasma membrane H(+)-ATPase upon salinity treatment. This is necessary for assisting plants to maintain highly negative membrane potential values and to exclude Na(+), or enable better K(+) retention in the cytosol under saline conditions.
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Affiliation(s)
- Jayakumar Bose
- School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Ana Rodrigo-Moreno
- School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Diwen Lai
- School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yanjie Xie
- School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Wenbiao Shen
- School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Sergey Shabala
- School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
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Adlimoghaddam A, Weihrauch D, O'Donnell MJ. Localization of K⁺, H⁺, Na⁺ and Ca²⁺ fluxes to the excretory pore in Caenorhabditis elegans: application of scanning ion-selective microelectrodes. ACTA ACUST UNITED AC 2014; 217:4119-22. [PMID: 25278475 DOI: 10.1242/jeb.112441] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Although Caenorhabditis elegans is commonly used as a model organism for studies of cell biology, development and physiology, the small size of the worm has impeded measurements of ion transport by the excretory cell and hypodermis. Here, we use the scanning ion-selective microelectrode technique to measure efflux and influx of K(+), H(+), Na(+) and Ca(2+) in intact worms. Transport of ions into, or out of, immobilized worms produces small gradients in ion concentration in the unstirred layer near the surface of the worm. These gradients are readily detectable with ion-selective microelectrodes and the corresponding ion fluxes can be estimated using the Fick equation. Our data show that effluxes of K(+), H(+), Na(+) and Ca(2+) are localized to the region of the excretory pore, consistent with release of these ions from the excretory cell, and that effluxes increase after experimental preloading with Na(+), K(+) or Ca(2+). In addition, the hypodermis is a site of Na(+) influx.
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Affiliation(s)
- Aida Adlimoghaddam
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2
| | - Dirk Weihrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2
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The heterodimeric glycoprotein hormone, GPA2/GPB5, regulates ion transport across the hindgut of the adult mosquito, Aedes aegypti. PLoS One 2014; 9:e86386. [PMID: 24466069 PMCID: PMC3896475 DOI: 10.1371/journal.pone.0086386] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 12/06/2013] [Indexed: 11/30/2022] Open
Abstract
A family of evolutionarily old hormones is the glycoprotein cysteine knot-forming heterodimers consisting of alpha- (GPA) and beta-subunits (GPB), which assemble by noncovalent bonds. In mammals, a common glycoprotein hormone alpha-subunit (GPA1) pairs with unique beta-subunits that establish receptor specificity, forming thyroid stimulating hormone (GPA1/TSHβ) and the gonadotropins luteinizing hormone (GPA1/LHβ), follicle stimulating hormone (GPA1/FSHβ), choriogonadotropin (GPA1/CGβ). A novel glycoprotein heterodimer was identified in vertebrates by genome analysis, called thyrostimulin, composed of two novel subunits, GPA2 and GPB5, and homologs occur in arthropods, nematodes and cnidarians, implying that this neurohormone system existed prior to the emergence of bilateral metazoans. In order to discern possible physiological roles of this hormonal signaling system in mosquitoes, we have isolated the glycoprotein hormone genes producing the alpha- and beta-subunits (AedaeGPA2 and AedaeGPB5) and assessed their temporal expression profiles in the yellow and dengue-fever vector, Aedes aegypti. We have also isolated a putative receptor for this novel mosquito hormone, AedaeLGR1, which contains features conserved with other glycoprotein leucine-rich repeating containing G protein-coupled receptors. AedaeLGR1 is expressed in tissues of the alimentary canal such as the midgut, Malpighian tubules and hindgut, suggesting that this novel mosquito glycoprotein hormone may regulate ionic and osmotic balance. Focusing on the hindgut in adult stage A. aegypti, where AedaeLGR1 was highly enriched, we utilized the Scanning Ion-selective Electrode Technique (SIET) to determine if AedaeGPA2/GPB5 modulated cation transport across this epithelial tissue. Our results suggest that AedaeGPA2/GPB5 does indeed participate in ionic and osmotic balance, since it appears to inhibit natriuresis and promote kaliuresis. Taken together, our findings imply this hormone may play an important role in ionic balance when levels of Na+ are limited and levels of K+ are in excess – such as during the digestion and assimilation of erythrocytes following vertebrate blood-feeding by females.
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Laohavisit A, Richards SL, Shabala L, Chen C, Colaço RD, Swarbreck SM, Shaw E, Dark A, Shabala S, Shang Z, Davies JM. Salinity-induced calcium signaling and root adaptation in Arabidopsis require the calcium regulatory protein annexin1. PLANT PHYSIOLOGY 2013; 163:253-62. [PMID: 23886625 PMCID: PMC3762646 DOI: 10.1104/pp.113.217810] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Salinity (NaCl) stress impairs plant growth and inflicts severe crop losses. In roots, increasing extracellular NaCl causes Ca²⁺ influx to elevate cytosolic free Ca²⁺ ([Ca²⁺](cyt)) as a second messenger for adaptive signaling. Amplification of the signal involves plasma membrane reduced nicotinamide adenine dinucleotide phosphate oxidase activation, with the resultant reactive oxygen species triggering Ca²⁺ influx. The genetic identities of the Ca²⁺-permeable channels involved in generating the [Ca²⁺](cyt) signal are unknown. Potential candidates in the model plant Arabidopsis (Arabidopsis thaliana) include annexin1 (AtANN1). Here, luminescent detection of [Ca²⁺](cyt) showed that AtANN1 responds to high extracellular NaCl by mediating reactive oxygen species-activated Ca²⁺ influx across the plasma membrane of root epidermal protoplasts. Electrophysiological analysis revealed that root epidermal plasma membrane Ca²⁺ influx currents activated by NaCl are absent from the Atann1 loss-of-function mutant. Both adaptive signaling and salt-responsive production of secondary roots are impaired in the loss-of-function mutant, thus identifying AtANN1 as a key component of root cell adaptation to salinity.
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Li X, Zhou F, Marcus DC, Wangemann P. Endolymphatic Na⁺ and K⁺ concentrations during cochlear growth and enlargement in mice lacking Slc26a4/pendrin. PLoS One 2013; 8:e65977. [PMID: 23741519 PMCID: PMC3669272 DOI: 10.1371/journal.pone.0065977] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 05/01/2013] [Indexed: 11/30/2022] Open
Abstract
Slc26a4 (Δ/Δ) mice are deaf, develop an enlarged membranous labyrinth, and thereby largely resemble the human phenotype where mutations of SLC26A4 cause an enlarged vestibular aqueduct and sensorineural hearing loss. The enlargement is likely caused by abnormal ion and fluid transport during the time of embryonic development, however, neither the mechanisms of ion transport nor the ionic composition of the luminal fluid during this time of development are known. Here we determine the ionic composition of inner ear fluids at the time at which the enlargement develops and the onset of expression of selected ion transporters. Concentrations of Na(+) and K(+) were measured with double-barreled ion-selective electrodes in the cochlea and the endolymphatic sac of Slc26a4 (Δ/+), which develop normal hearing, and of Slc26a4 (Δ/Δ) mice, which fail to develop hearing. The expression of specific ion transporters was examined by quantitative RT-PCR and immunohistochemistry. High Na(+) (∼141 mM) and low K(+) concentrations (∼11 mM) were found at embryonic day (E) 16.5 in cochlear endolymph of Slc26a4 (Δ/+) and Slc26a4 (Δ/Δ) mice. Shortly before birth the K(+) concentration began to rise. Immediately after birth (postnatal day 0), the Na(+) and K(+) concentrations in cochlear endolymph were each ∼80 mM. In Slc26a4 (Δ/Δ) mice, the rise in the K(+) concentration occurred with a ∼3 day delay. K(+) concentrations were also found to be low (∼15 mM) in the embryonic endolymphatic sac. The onset of expression of the K(+) channel KCNQ1 and the Na(+)/2Cl(-)/K(+) cotransporter SLC12A2 occurred in the cochlea at E19.5 in Slc26a4 (Δ/+) and Slc26a4 (Δ/Δ) mice. These data demonstrate that endolymph, at the time at which the enlargement develops, is a Na(+)-rich fluid, which transitions into a K(+)-rich fluid before birth. The data suggest that the endolymphatic enlargement caused by a loss of Slc26a4 is a consequence of disrupted Na(+) transport.
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Affiliation(s)
- Xiangming Li
- Anatomy and Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
| | - Fei Zhou
- Anatomy and Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
| | - Daniel C. Marcus
- Anatomy and Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
| | - Philine Wangemann
- Anatomy and Physiology Department, Kansas State University, Manhattan, Kansas, United States of America
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Jayakannan M, Bose J, Babourina O, Rengel Z, Shabala S. Salicylic acid improves salinity tolerance in Arabidopsis by restoring membrane potential and preventing salt-induced K+ loss via a GORK channel. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:2255-68. [PMID: 23580750 PMCID: PMC3654417 DOI: 10.1093/jxb/ert085] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Despite numerous reports implicating salicylic acid (SA) in plant salinity responses, the specific ionic mechanisms of SA-mediated adaptation to salt stress remain elusive. To address this issue, a non-invasive microelectrode ion flux estimation technique was used to study kinetics of NaCl-induced net ion fluxes in Arabidopsis thaliana in response to various SA concentrations and incubation times. NaCl-induced K(+) efflux and H(+) influx from the mature root zone were both significantly decreased in roots pretreated with 10-500 μM SA, with strongest effect being observed in the 10-50 μM SA range. Considering temporal dynamics (0-8-h SA pretreatment), the 1-h pretreatment was most effective in enhancing K(+) retention in the cytosol. The pharmacological, membrane potential, and shoot K(+) and Na(+) accumulation data were all consistent with the model in which the SA pretreatment enhanced activity of H(+)-ATPase, decreased NaCl-induced membrane depolarization, and minimized NaCl-induced K(+) leakage from the cell within the first hour of salt stress. In long-term treatments, SA increased shoot K(+) and decreased shoot Na(+) accumulation. The short-term NaCl-induced K(+) efflux was smallest in the gork1-1 mutant, followed by the rbohD mutant, and was highest in the wild type. Most significantly, the SA pretreatment decreased the NaCl-induced K(+) efflux from rbohD and the wild type to the level of gork1-1, whereas no effect was observed in gork1-1. These data provide the first direct evidence that the SA pretreatment ameliorates salinity stress by counteracting NaCl-induced membrane depolarization and by decreasing K(+) efflux via GORK channels.
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Affiliation(s)
- Maheswari Jayakannan
- School of Earth and Environment, University of Western Australia, Perth, Australia
- School of Agricultural Science and Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Australia
| | - Jayakumar Bose
- School of Agricultural Science and Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Australia
| | - Olga Babourina
- School of Earth and Environment, University of Western Australia, Perth, Australia
| | - Zed Rengel
- School of Earth and Environment, University of Western Australia, Perth, Australia
| | - Sergey Shabala
- School of Agricultural Science and Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Australia
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Bonales-Alatorre E, Pottosin I, Shabala L, Chen ZH, Zeng F, Jacobsen SE, Shabala S. Differential activity of plasma and vacuolar membrane transporters contributes to genotypic differences in salinity tolerance in a Halophyte Species, Chenopodium quinoa. Int J Mol Sci 2013; 14:9267-85. [PMID: 23629664 PMCID: PMC3676782 DOI: 10.3390/ijms14059267] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 04/13/2013] [Accepted: 04/15/2013] [Indexed: 11/29/2022] Open
Abstract
Halophytes species can be used as a highly convenient model system to reveal key ionic and molecular mechanisms that confer salinity tolerance in plants. Earlier, we reported that quinoa (Chenopodium quinoa Willd.), a facultative C3 halophyte species, can efficiently control the activity of slow (SV) and fast (FV) tonoplast channels to match specific growth conditions by ensuring that most of accumulated Na+ is safely locked in the vacuole (Bonales-Alatorre et al. (2013) Plant Physiology). This work extends these finding by comparing the properties of tonoplast FV and SV channels in two quinoa genotypes contrasting in their salinity tolerance. The work is complemented by studies of the kinetics of net ion fluxes across the plasma membrane of quinoa leaf mesophyll tissue. Our results suggest that multiple mechanisms contribute towards genotypic differences in salinity tolerance in quinoa. These include: (i) a higher rate of Na+ exclusion from leaf mesophyll; (ii) maintenance of low cytosolic Na+ levels; (iii) better K+ retention in the leaf mesophyll; (iv) a high rate of H+ pumping, which increases the ability of mesophyll cells to restore their membrane potential; and (v) the ability to reduce the activity of SV and FV channels under saline conditions. These mechanisms appear to be highly orchestrated, thus enabling the remarkable overall salinity tolerance of quinoa species.
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Affiliation(s)
- Edgar Bonales-Alatorre
- School of Agricultural Science and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia; E-Mails: (E.B.-A.); (L.S.); (F.Z.)
- University Centre for Biomedical Research, University of Colima, 28045 Colima, Mexico; E-Mail:
| | - Igor Pottosin
- University Centre for Biomedical Research, University of Colima, 28045 Colima, Mexico; E-Mail:
| | - Lana Shabala
- School of Agricultural Science and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia; E-Mails: (E.B.-A.); (L.S.); (F.Z.)
| | - Zhong-Hua Chen
- School of Science and Health, University of Western Sydney, Richmond, NSW 2753, Australia; E-Mail:
| | - Fanrong Zeng
- School of Agricultural Science and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia; E-Mails: (E.B.-A.); (L.S.); (F.Z.)
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Sven-Erik Jacobsen
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Højbakkegaard Allé 13, 2630 Taastrup, Denmark; E-Mail:
| | - Sergey Shabala
- School of Agricultural Science and Tasmanian Institute for Agriculture, University of Tasmania, Private Bag 54, Hobart, TAS 7001, Australia; E-Mails: (E.B.-A.); (L.S.); (F.Z.)
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Newman I, Chen SL, Porterfield DM, Sun J. Non-invasive flux measurements using microsensors: theory, limitations, and systems. Methods Mol Biol 2013; 913:101-17. [PMID: 22895754 DOI: 10.1007/978-1-61779-986-0_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Knowledge of the fluxes of ions and neutral molecules across the outer membrane or boundary of living tissues and cells is an important strand of applied molecular biology. Such fluxes can be measured non-invasively with good resolution in time and space. Two systems (MIFE™ and SIET) have been developed and have become widely used to implement this technique, and they are commercially available. This Chapter is the first comparative description of these two systems. It gives the context, the basic underlying theory, practical limitations inherent in the technique, theoretical developments, guidance on the practicalities of the technique, and the functionality of the two systems. Although the technique is strongly relevant to plant salt tolerance and other plant stresses (drought, temperature, pollutants, waterlogging), it also has rich relevance throughout biomedical studies and the molecular genetics of transport proteins.
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Affiliation(s)
- Ian Newman
- School of Mathematics and Physics, University of Tasmania, Hobart, TAS, Australia.
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Monitoring ion activities in and around cells using ion-selective liquid-membrane microelectrodes. SENSORS 2013; 13:984-1003. [PMID: 23322102 PMCID: PMC3574717 DOI: 10.3390/s130100984] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 12/31/2012] [Accepted: 01/02/2013] [Indexed: 11/24/2022]
Abstract
Determining the effective concentration (i.e., activity) of ions in and around living cells is important to our understanding of the contribution of those ions to cellular function. Moreover, monitoring changes in ion activities in and around cells is informative about the actions of the transporters and/or channels operating in the cell membrane. The activity of an ion can be measured using a glass microelectrode that includes in its tip a liquid-membrane doped with an ion-selective ionophore. Because these electrodes can be fabricated with tip diameters that are less than 1 μm, they can be used to impale single cells in order to monitor the activities of intracellular ions. This review summarizes the history, theory, and practice of ion-selective microelectrode use and brings together a number of classic and recent examples of their usefulness in the realm of physiological study.
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