101
|
Carraretto L, Teardo E, Checchetto V, Finazzi G, Uozumi N, Szabo I. Ion Channels in Plant Bioenergetic Organelles, Chloroplasts and Mitochondria: From Molecular Identification to Function. MOLECULAR PLANT 2016; 9:371-395. [PMID: 26751960 DOI: 10.1016/j.molp.2015.12.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/22/2015] [Accepted: 12/01/2015] [Indexed: 06/05/2023]
Abstract
Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioenergetic organelles, chloroplasts and mitochondria, leading to the molecular identification and functional characterization of several ion transport systems in recent years. Here we focus on channels that mediate relatively high-rate ion and water flux and summarize the current knowledge in this field, focusing on targeting mechanisms, proteomics, electrophysiology, and physiological function. In addition, since chloroplasts evolved from a cyanobacterial ancestor, we give an overview of the information available about cyanobacterial ion channels and discuss the evolutionary origin of chloroplast channels. The recent molecular identification of some of these ion channels allowed their physiological functions to be studied using genetically modified Arabidopsis plants and cyanobacteria. The view is emerging that alteration of chloroplast and mitochondrial ion homeostasis leads to organelle dysfunction, which in turn significantly affects the energy metabolism of the whole organism. Clear-cut identification of genes encoding for channels in these organelles, however, remains a major challenge in this rapidly developing field. Multiple strategies including bioinformatics, cell biology, electrophysiology, use of organelle-targeted ion-sensitive probes, genetics, and identification of signals eliciting specific ion fluxes across organelle membranes should provide a better understanding of the physiological role of organellar channels and their contribution to signaling pathways in plants in the future.
Collapse
Affiliation(s)
- Luca Carraretto
- Department of Biology, University of Padova, Padova 35121, Italy
| | - Enrico Teardo
- Department of Biology, University of Padova, Padova 35121, Italy; CNR Institute of Neuroscience, University of Padova, Padova 35121, Italy
| | | | - Giovanni Finazzi
- UMR 5168 Laboratoire de Physiologie Cellulaire Végétale (LPCV) CNRS/ UJF / INRA / CEA, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), CEA Grenoble, 38054 Grenoble, France.
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padova 35121, Italy; CNR Institute of Neuroscience, University of Padova, Padova 35121, Italy.
| |
Collapse
|
102
|
Thakur S, Sharma SS. Characterization of seed germination, seedling growth, and associated metabolic responses of Brassica juncea L. cultivars to elevated nickel concentrations. PROTOPLASMA 2016; 253:571-80. [PMID: 26025262 DOI: 10.1007/s00709-015-0835-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 05/17/2015] [Indexed: 05/05/2023]
Abstract
Seed germination and seedling growth responses of three Brassica juncea L. cultivars, namely Varuna, Kranti, and Pusa Jai Kisan, to nickel have been characterized. Ni suppressed the seed germination differentially, suppression being greater in cv. Kranti than in others. On the basis of seedling growth performance, cv. Varuna proved most tolerant to Ni. The Ni accumulation in seedlings differed strongly among the three cultivars. The lowest and highest Ni contents were observed in the seedlings of cvs. Kranti and Pusa Jai Kisan, respectively. Despite substantial Ni accumulation, cv. Varuna was most tolerant to Ni. Ni accumulation in seedlings was accompanied by differentially altered Fe and K contents and increased levels of non-protein thiols and free proline. The O2- and H2O2 contents and their respective scavenging enzymes in the seedlings responded differentially to the Ni treatment suggesting the involvement of redox imbalance in the development of Ni toxicity. Interestingly, the greater Ni tolerance of cv. Varuna coincided with the elevated constitutive activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX). The data have implications for seedling establishment under Ni-rich conditions and in turn for phytoremediation.
Collapse
Affiliation(s)
- Sveta Thakur
- Department of Biosciences, Himachal Pradesh University, Shimla, 171005, India
| | - Shanti S Sharma
- Department of Biosciences, Himachal Pradesh University, Shimla, 171005, India.
| |
Collapse
|
103
|
Vitali V, Sutka M, Amodeo G, Chara O, Ozu M. The Water to Solute Permeability Ratio Governs the Osmotic Volume Dynamics in Beetroot Vacuoles. FRONTIERS IN PLANT SCIENCE 2016; 7:1388. [PMID: 27695468 PMCID: PMC5024706 DOI: 10.3389/fpls.2016.01388] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 08/31/2016] [Indexed: 05/11/2023]
Abstract
Plant cell vacuoles occupy up to 90% of the cell volume and, beyond their physiological function, are constantly subjected to water and solute exchange. The osmotic flow and vacuole volume dynamics relies on the vacuole membrane -the tonoplast- and its capacity to regulate its permeability to both water and solutes. The osmotic permeability coefficient (Pf ) is the parameter that better characterizes the water transport when submitted to an osmotic gradient. Usually, Pf determinations are made in vitro from the initial rate of volume change, when a fast (almost instantaneous) osmolality change occurs. When aquaporins are present, it is accepted that initial volume changes are only due to water movements. However, in living cells osmotic changes are not necessarily abrupt but gradually imposed. Under these conditions, water flux might not be the only relevant driving force shaping the vacuole volume response. In this study, we quantitatively investigated volume dynamics of isolated Beta vulgaris root vacuoles under progressively applied osmotic gradients at different pH, a condition that modifies the tonoplast Pf . We followed the vacuole volume changes while simultaneously determining the external osmolality time-courses and analyzing these data with mathematical modeling. Our findings indicate that vacuole volume changes, under progressively applied osmotic gradients, would not depend on the membrane elastic properties, nor on the non-osmotic volume of the vacuole, but on water and solute fluxes across the tonoplast. We found that the volume of the vacuole at the steady state is determined by the ratio of water to solute permeabilites (Pf /Ps ), which in turn is ruled by pH. The dependence of the permeability ratio on pH can be interpreted in terms of the degree of aquaporin inhibition and the consequently solute transport modulation. This is relevant in many plant organs such as root, leaves, cotyledons, or stems that perform extensive rhythmic growth movements, which very likely involve considerable cell volume changes within seconds to hours.
Collapse
Affiliation(s)
- Victoria Vitali
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Instituto de Biodiversidad y Biología Experimental y Aplicada, Universidad de Buenos Aires and Consejo Nacional de Investigaciones Científicas y TécnicasBuenos Aires, Argentina
| | - Moira Sutka
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Instituto de Biodiversidad y Biología Experimental y Aplicada, Universidad de Buenos Aires and Consejo Nacional de Investigaciones Científicas y TécnicasBuenos Aires, Argentina
| | - Gabriela Amodeo
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Instituto de Biodiversidad y Biología Experimental y Aplicada, Universidad de Buenos Aires and Consejo Nacional de Investigaciones Científicas y TécnicasBuenos Aires, Argentina
| | - Osvaldo Chara
- System Biology Group (SysBio), Institute of Physics of Liquids and Biological Systems (IFLYSIB) CONICET, University of La PlataLa Plata, Argentina
- Center for Information Services and High Performance Computing, Technische Universität DresdenDresden, Germany
| | - Marcelo Ozu
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Instituto de Biodiversidad y Biología Experimental y Aplicada, Universidad de Buenos Aires and Consejo Nacional de Investigaciones Científicas y TécnicasBuenos Aires, Argentina
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Instituto de Fisiología y Biofísica (IFIBIO–Houssay), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y TécnicasBuenos Aires, Argentina
- *Correspondence: Marcelo Ozu
| |
Collapse
|
104
|
Bihmidine S, Julius BT, Dweikat I, Braun DM. Tonoplast Sugar Transporters (SbTSTs) putatively control sucrose accumulation in sweet sorghum stems. PLANT SIGNALING & BEHAVIOR 2016; 11:e1117721. [PMID: 26619184 PMCID: PMC4871674 DOI: 10.1080/15592324.2015.1117721] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 11/04/2015] [Indexed: 05/05/2023]
Abstract
Carbohydrates are differentially partitioned in sweet versus grain sorghums. While the latter preferentially accumulate starch in the grain, the former primarily store large amounts of sucrose in the stem. Previous work determined that neither sucrose metabolizing enzymes nor changes in Sucrose transporter (SUT) gene expression accounted for the carbohydrate partitioning differences. Recently, 2 additional classes of sucrose transport proteins, Tonoplast Sugar Transporters (TSTs) and SWEETs, were identified; thus, we examined whether their expression tracked sucrose accumulation in sweet sorghum stems. We determined 2 TSTs were differentially expressed in sweet vs. grain sorghum stems, likely underlying the massive difference in sucrose accumulation. A model illustrating potential roles for different classes of sugar transport proteins in sorghum sugar partitioning is discussed.
Collapse
Affiliation(s)
- Saadia Bihmidine
- a Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri , 116 Tucker Hall, Columbia , MO , USA
| | - Benjamin T Julius
- a Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri , 116 Tucker Hall, Columbia , MO , USA
| | - Ismail Dweikat
- b Department of Agronomy and Horticulture , University of Nebraska-Lincoln , 365 Keim Hall, Lincoln , NE , USA
| | - David M Braun
- a Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri , 116 Tucker Hall, Columbia , MO , USA
| |
Collapse
|
105
|
Navrátil T, Nováková K, Josypčuk B, Sokolová R, Šestáková I. Voltammetric detection of phytochelatin transported across unmodified and protoplast modified model phospholipid membranes. MONATSHEFTE FUR CHEMIE 2015. [DOI: 10.1007/s00706-015-1591-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
106
|
Wang Y, Dindas J, Rienmüller F, Krebs M, Waadt R, Schumacher K, Wu WH, Hedrich R, Roelfsema MRG. Cytosolic Ca(2+) Signals Enhance the Vacuolar Ion Conductivity of Bulging Arabidopsis Root Hair Cells. MOLECULAR PLANT 2015; 8:1665-74. [PMID: 26232520 DOI: 10.1016/j.molp.2015.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 06/16/2015] [Accepted: 07/21/2015] [Indexed: 05/23/2023]
Abstract
Plant cell expansion depends on the uptake of solutes across the plasma membrane and their storage within the vacuole. In contrast to the well-studied plasma membrane, little is known about the regulation of ion transport at the vacuolar membrane. We therefore established an experimental approach to study vacuolar ion transport in intact Arabidopsis root cells, with multi-barreled microelectrodes. The subcellular position of electrodes was detected by imaging current-injected fluorescent dyes. Comparison of measurements with electrodes in the cytosol and vacuole revealed an average vacuolar membrane potential of -31 mV. Voltage clamp recordings of single vacuoles resolved the activity of voltage-independent and slowly deactivating channels. In bulging root hairs that express the Ca(2+) sensor R-GECO1, rapid elevation of the cytosolic Ca(2+) concentration was observed, after impalement with microelectrodes, or injection of the Ca(2+) chelator BAPTA. Elevation of the cytosolic Ca(2+) level stimulated the activity of voltage-independent channels in the vacuolar membrane. Likewise, the vacuolar ion conductance was enhanced during a sudden increase of the cytosolic Ca(2+) level in cells injected with fluorescent Ca(2+) indicator FURA-2. These data thus show that cytosolic Ca(2+) signals can rapidly activate vacuolar ion channels, which may prevent rupture of the vacuolar membrane, when facing mechanical forces.
Collapse
Affiliation(s)
- Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Julian Dindas
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany
| | - Florian Rienmüller
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany
| | - Melanie Krebs
- Centre for Organismal Studies, Developmental Biology of Plants, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Rainer Waadt
- Centre for Organismal Studies, Developmental Biology of Plants, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Karin Schumacher
- Centre for Organismal Studies, Developmental Biology of Plants, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Wei-Hua Wu
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Rainer Hedrich
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany; College of Science, King Saud University (KSU), Riyadh, Saudi Arabia
| | - M Rob G Roelfsema
- Molecular Plant Physiology and Biophysics, Julius-von-Sachs Institute for Biosciences, Biocenter, Würzburg University, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany.
| |
Collapse
|
107
|
Volkov V. Salinity tolerance in plants. Quantitative approach to ion transport starting from halophytes and stepping to genetic and protein engineering for manipulating ion fluxes. FRONTIERS IN PLANT SCIENCE 2015; 6:873. [PMID: 26579140 PMCID: PMC4621421 DOI: 10.3389/fpls.2015.00873] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 10/01/2015] [Indexed: 05/18/2023]
Abstract
Ion transport is the fundamental factor determining salinity tolerance in plants. The Review starts from differences in ion transport between salt tolerant halophytes and salt-sensitive plants with an emphasis on transport of potassium and sodium via plasma membranes. The comparison provides introductory information for increasing salinity tolerance. Effects of salt stress on ion transport properties of membranes show huge opportunities for manipulating ion fluxes. Further steps require knowledge about mechanisms of ion transport and individual genes of ion transport proteins. Initially, the Review describes methods to measure ion fluxes, the independent set of techniques ensures robust and reliable basement for quantitative approach. The Review briefly summarizes current data concerning Na(+) and K(+) concentrations in cells, refers to primary thermodynamics of ion transport and gives special attention to individual ion channels and transporters. Simplified scheme of a plant cell with known transport systems at the plasma membrane and tonoplast helps to imagine the complexity of ion transport and allows choosing specific transporters for modulating ion transport. The complexity is enhanced by the influence of cell size and cell wall on ion transport. Special attention is given to ion transporters and to potassium and sodium transport by HKT, HAK, NHX, and SOS1 proteins. Comparison between non-selective cation channels and ion transporters reveals potential importance of ion transporters and the balance between the two pathways of ion transport. Further on the Review describes in detail several successful attempts to overexpress or knockout ion transporters for changing salinity tolerance. Future perspectives are questioned with more attention given to promising candidate ion channels and transporters for altered expression. Potential direction of increasing salinity tolerance by modifying ion channels and transporters using single point mutations is discussed and questioned. An alternative approach from synthetic biology is to create new regulation networks using novel transport proteins with desired properties for transforming agricultural crops. The approach had not been widely used earlier; it leads also to theoretical and pure scientific aspects of protein chemistry, structure-function relations of membrane proteins, systems biology and physiology of stress and ion homeostasis. Summarizing, several potential ways are aimed at required increase in salinity tolerance of plants of interest.
Collapse
Affiliation(s)
- Vadim Volkov
- Faculty of Life Sciences and Computing, London Metropolitan UniversityLondon, UK
| |
Collapse
|
108
|
Winter K, Holtum JAM, Smith JAC. Crassulacean acid metabolism: a continuous or discrete trait? THE NEW PHYTOLOGIST 2015; 208:73-8. [PMID: 25975197 DOI: 10.1111/nph.13446] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/22/2015] [Indexed: 05/27/2023]
Abstract
The key components of crassulacean acid metabolism (CAM) - nocturnal fixation of atmospheric CO2 and its processing via Rubisco in the subsequent light period - are now reasonably well understood in terms of the biochemical reactions defining this water-saving mode of carbon assimilation. Phenotypically, however, the degree to which plants engage in the CAM cycle relative to regular C3 photosynthesis is highly variable. Depending upon species, ontogeny and environment, the contribution of nocturnal CO2 fixation to 24-h carbon gain can range continuously from close to 0% to 100%. Nevertheless, not all possible combinations of light and dark CO2 fixation appear equally common. Large-scale surveys of carbon-isotope ratios typically show a strongly bimodal frequency distribution, with relatively few intermediate values. Recent research has revealed that many species capable of low-level CAM activity are nested within the peak of C3 -type isotope signatures. While questions remain concerning the adaptive significance of dark CO2 fixation in such species, plants with low-level CAM should prove valuable models for investigating the discrete changes in genetic architecture and gene expression that have enabled the evolutionary transition from C3 to CAM.
Collapse
Affiliation(s)
- Klaus Winter
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancón, Republic of Panama
| | - Joseph A M Holtum
- Centre for Tropical Biodiversity and Climate Change, James Cook University, Townsville, QLD, 4811, Australia
| | - J Andrew C Smith
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| |
Collapse
|
109
|
Festa M, Lagostena L, Carpaneto A. Using the plant vacuole as a biological system to investigate the functional properties of exogenous channels and transporters. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:607-12. [PMID: 26431786 DOI: 10.1016/j.bbamem.2015.09.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 07/31/2015] [Accepted: 09/25/2015] [Indexed: 01/15/2023]
Abstract
Plant cells possess a large intracellular compartment that animal cells do not, the central vacuole, which has been investigated for a long time. The central vacuole can occupy up to 90% of the cellular volume and, differently from intracellular organelles from animal cells such as lysosomes or endosomes, it is easy to isolate. Because of its large dimension (up to 40 μm diameter) it can be successfully studied using the classical patch-clamp technique. Following the idea that the vacuolar membrane could be used as a convenient model to characterize the functional properties of channel-forming peptides, we verified that the phytotoxic lipodepsipeptide Syringopeptin 25A from Pseudomonas syringae pv syringae was able to form ionic pores in sugar beet vacuoles and we performed a detailed biophysical analysis. Recently, we extended the use of plant vacuoles to the expression and functional characterization of animal intracellular transporters, namely rat CLC-7, and channels, i.e. human TPC2. Since endo-lysosomal transporters and channels are still largely unexplored, principally because their intracellular localization renders them difficult to study, we believe that this novel approach will prove to be a powerful system for the investigation of the molecular mechanisms of exogenous transporters and channels. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.
Collapse
Affiliation(s)
- M Festa
- Institute of Biophysics (IBF), CNR, Via De Marini 6, 16149 Genova, Italy
| | - L Lagostena
- Institute of Biophysics (IBF), CNR, Via De Marini 6, 16149 Genova, Italy
| | - A Carpaneto
- Institute of Biophysics (IBF), CNR, Via De Marini 6, 16149 Genova, Italy.
| |
Collapse
|
110
|
Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network. Nat Commun 2015; 6:8142. [PMID: 26356302 PMCID: PMC4647861 DOI: 10.1038/ncomms9142] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 07/22/2015] [Indexed: 12/19/2022] Open
Abstract
In addition to proteins, L-phenylalanine is a versatile precursor for thousands of plant metabolites. Production of phenylalanine-derived compounds is a complex multi-compartmental process using phenylalanine synthesized predominantly in plastids as precursor. The transporter(s) exporting phenylalanine from plastids, however, remains unknown. Here, a gene encoding a Petunia hybrida plastidial cationic amino-acid transporter (PhpCAT) functioning in plastidial phenylalanine export is identified based on homology to an Escherichia coli phenylalanine transporter and co-expression with phenylalanine metabolic genes. Radiolabel transport assays show that PhpCAT exports all three aromatic amino acids. PhpCAT downregulation and overexpression result in decreased and increased levels, respectively, of phenylalanine-derived volatiles, as well as phenylalanine, tyrosine and their biosynthetic intermediates. Metabolic flux analysis reveals that flux through the plastidial phenylalanine biosynthetic pathway is reduced in PhpCAT RNAi lines, suggesting that the rate of phenylalanine export from plastids contributes to regulating flux through the aromatic amino-acid network.
Collapse
|
111
|
Abstract
Subcellular flavonoid transport and its underlying regulatory mechanisms are still poorly understood, but are fascinating research frontiers in plant science. Recent studies support and further extend previous hypotheses indicating that vacuolar sequestration of flavonoids involves vesicle trafficking, membrane transporters, and glutathione S-transferase (GST). However, the question remains to be addressed of how three distinct but nonexclusive mechanisms are functionally integrated into diverse but redundant transport routes for vacuolar sequestration or extracellular secretion of flavonoids. In this review, I highlight recent progress in understanding flavonoid-transporting vesicle behavior and properties, GST and membrane transporter functions and mechanisms, and flavonoid transport substrate specificity and preference.
Collapse
Affiliation(s)
- Jian Zhao
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| |
Collapse
|
112
|
Fettke J, Fernie AR. Intracellular and cell-to-apoplast compartmentation of carbohydrate metabolism. TRENDS IN PLANT SCIENCE 2015; 20:490-497. [PMID: 26008154 DOI: 10.1016/j.tplants.2015.04.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/20/2015] [Accepted: 04/28/2015] [Indexed: 06/04/2023]
Abstract
In most plants, carbohydrates represent the major energy store as well as providing the building blocks for essential structural polymers. Although the major pathways for carbohydrate biosynthesis, degradation, and transport are well characterized, several key steps have only recently been discovered. In addition, several novel minor metabolic routes have been uncovered in the past few years. Here we review current studies of plant carbohydrate metabolism detailing the expanding compendium of functionally characterized transport proteins as well as our deeper comprehension of more minor and conditionally activated metabolic pathways. We additionally explore the pertinent questions that will allow us to enhance our understanding of the response of both major and minor carbohydrate fluxes to changing cellular circumstances.
Collapse
Affiliation(s)
- Joerg Fettke
- Biopolymer Analytics, University of Potsdam, Potsdam-Golm, Germany.
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| |
Collapse
|
113
|
Bihmidine S, Baker RF, Hoffner C, Braun DM. Sucrose accumulation in sweet sorghum stems occurs by apoplasmic phloem unloading and does not involve differential Sucrose transporter expression. BMC PLANT BIOLOGY 2015; 15:186. [PMID: 26223524 PMCID: PMC4518677 DOI: 10.1186/s12870-015-0572-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/16/2015] [Indexed: 05/19/2023]
Abstract
BACKGROUND Sorghum (Sorghum bicolor L. Moench) cultivars store non-structural carbohydrates predominantly as either starch in seeds (grain sorghums) or sugars in stems (sweet sorghums). Previous research determined that sucrose accumulation in sweet sorghum stems was not correlated with the activities of enzymes functioning in sucrose metabolism, and that an apoplasmic transport step may be involved in stem sucrose accumulation. However, the sucrose unloading pathway from stem phloem to storage parenchyma cells remains unelucidated. Sucrose transporters (SUTs) transport sucrose across membranes, and have been proposed to function in sucrose partitioning differences between sweet and grain sorghums. The purpose of this study was to characterize the key differences in carbohydrate accumulation between a sweet and a grain sorghum, to define the path sucrose may follow for accumulation in sorghum stems, and to determine the roles played by sorghum SUTs in stem sucrose accumulation. RESULTS Dye tracer studies to determine the sucrose transport route revealed that, for both the sweet sorghum cultivar Wray and grain sorghum cultivar Macia, the phloem in the stem veins was symplasmically isolated from surrounding cells, suggesting sucrose was apoplasmically unloaded. Once in the phloem apoplasm, a soluble tracer diffused from the vein to stem parenchyma cell walls, indicating the lignified mestome sheath encompassing the vein did not prevent apoplasmic flux outside of the vein. To characterize carbohydrate partitioning differences between Wray and Macia, we compared the growth, stem juice volume, solute contents, SbSUTs gene expression, and additional traits. Contrary to previous findings, we detected no significant differences in SbSUTs gene expression within stem tissues. CONCLUSIONS Phloem sieve tubes within sweet and grain sorghum stems are symplasmically isolated from surrounding cells; hence, unloading from the phloem likely occurs apoplasmically, thereby defining the location of the previously postulated step for sucrose transport. Additionally, no changes in SbSUTs gene expression were detected in sweet vs. grain sorghum stems, suggesting alterations in SbSUT transcript levels do not account for the carbohydrate partitioning differences between cultivars. A model illustrating sucrose phloem unloading and movement to stem storage parenchyma, and highlighting roles for sucrose transport proteins in sorghum stems is discussed.
Collapse
Affiliation(s)
- Saadia Bihmidine
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 110 Tucker Hall, Columbia, MO, 65211, USA.
| | - R Frank Baker
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 110 Tucker Hall, Columbia, MO, 65211, USA.
- University of Missouri Molecular Cytology Core, 120 Bond Life Sciences Center, 1201 Rollins Street, Columbia, MO, 65211-7310, USA.
| | - Cassandra Hoffner
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 110 Tucker Hall, Columbia, MO, 65211, USA.
- Sigma-Aldrich Biotech, 545 S. Ewing, Saint Louis, MO, 63103, USA.
| | - David M Braun
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 110 Tucker Hall, Columbia, MO, 65211, USA.
| |
Collapse
|
114
|
Zhang C, Hicks GR, Raikhel NV. Molecular Composition of Plant Vacuoles: Important but Less Understood Regulations and Roles of Tonoplast Lipids. PLANTS 2015; 4:320-33. [PMID: 27135331 PMCID: PMC4844321 DOI: 10.3390/plants4020320] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 05/21/2015] [Accepted: 06/03/2015] [Indexed: 11/16/2022]
Abstract
The vacuole is an essential organelle for plant growth and development. It is the location for the storage of nutrients; such as sugars and proteins; and other metabolic products. Understanding the mechanisms of vacuolar trafficking and molecule transport across the vacuolar membrane is of great importance in understanding basic plant development and cell biology and for crop quality improvement. Proteins play important roles in vacuolar trafficking; such proteins include Rab GTPase signaling proteins; cargo recognition receptors; and SNAREs (Soluble NSF Attachment Protein Receptors) that are involved in membrane fusion. Some vacuole membrane proteins also serve as the transporters or channels for transport across the tonoplast. Less understood but critical are the roles of lipids in vacuolar trafficking. In this review, we will first summarize molecular composition of plant vacuoles and we will then discuss our latest understanding on the role of lipids in plant vacuolar trafficking and a surprising connection to ribosome function through the study of ribosomal mutants.
Collapse
Affiliation(s)
- Chunhua Zhang
- Center for Plant Cell Biology & Department of Botany and Plant Sciences, University of California, 900 University Ave., Riverside, CA 92521, USA.
| | - Glenn R Hicks
- Center for Plant Cell Biology & Department of Botany and Plant Sciences, University of California, 900 University Ave., Riverside, CA 92521, USA.
| | - Natasha V Raikhel
- Center for Plant Cell Biology & Department of Botany and Plant Sciences, University of California, 900 University Ave., Riverside, CA 92521, USA.
| |
Collapse
|
115
|
Hedrich R, Sauer N, Neuhaus HE. Sugar transport across the plant vacuolar membrane: nature and regulation of carrier proteins. CURRENT OPINION IN PLANT BIOLOGY 2015; 25:63-70. [PMID: 26000864 DOI: 10.1016/j.pbi.2015.04.008] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 04/16/2015] [Accepted: 04/30/2015] [Indexed: 05/06/2023]
Abstract
The ability of higher plants to store sugars is of crucial importance for plant development, adaption to endogenous or environmental cues and for the economic value of crop species. Sugar storage and accumulation, and its homeostasis in plant cells are managed by the vacuole. Although transport of sugars across the vacuolar membrane has been monitored for about four decades, the molecular entities of the transporters involved have been identified in the last 10 years only. Thus, it is just recently that our pictures of the transporters that channel the sugar load across the tonoplast have gained real shape. Here we describe the molecular nature and regulation of an important group of tonoplast sugar transporter (TST) allowing accumulation of sugars against large concentration gradients. In addition, we report on proton-driven tonoplast sugar exporters and on facilitators, which are also involved in balancing cytosolic and vacuolar sugar levels.
Collapse
Affiliation(s)
- Rainer Hedrich
- Molecular Plant Physiology and Biophysics, University of Würzburg, Germany
| | - Norbert Sauer
- Molecular Plant Physiology, University of Erlangen-Nuremberg, Germany
| | | |
Collapse
|
116
|
Badran EG, Abogadallah GM, Nada RM, Nemat Alla MM. Role of glycine in improving the ionic and ROS homeostasis during NaCl stress in wheat. PROTOPLASMA 2015; 252:835-844. [PMID: 25344655 DOI: 10.1007/s00709-014-0720-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 10/13/2014] [Indexed: 06/04/2023]
Abstract
Nine-day-old wheat seedlings were treated with NaCl at 75, 150, and 225 mM for 15 days in the absence or presence of 5 mM glycine. NaCl particularly at 150 and 225 mM led to significant reductions in fresh and dry weights, chlorophylls, carotenoids, Ca(2+), K(+), and K(+)/Na(+) ratio. Contrarily, there were significant accumulations in Na(+), malondialdehyde (MDA), H2O2, soluble sugars, and proline concomitant with inhibitions in enzymatic and non-enzymatic antioxidants and in Rubisco. In the meantime, the transcript level of alternative oxidase (AOX) was highly upregulated by NaCl; the upregulation was greatest with the lowest concentration. However, the transcript level of H(+)/Na(+) antiporter exchanger (NHX1) was decreased by 75 and 150 mM NaCl but increased by 225 mM. Similarly, the transcript level of salt overly sensitive 1 (SOS1) was upregulated by only 225 mM. Nonetheless, the application of glycine mostly overcame the varied impacts of NaCl on growth, MDA, H2O2, pigments, metabolites, and elements. Moreover, glycine elevated enzymatic and non-enzymatic antioxidants to reach most likely the levels of the respective control. On the contrary, much induction was detected in Rubisco. The transcript levels of AOX, NHX1, and SOS1 were further upregulated; the upregulation of AOX was most pronounced with the highest NaCl concentration in the presence of glycine and only with 75 and 150 mM NaCl for NHX1 and SOS1. The increase in antioxidants concomitant with the decrease in MDA and H2O2 reveals that ROS scavenging system became more efficient in NaCl-treated wheat following glycine application, concluding that glycine could ameliorate wheat tolerance to salinity. Moreover, lowering Na(+) by glycine and mitigation of the decreased K(+)/Na(+) ratio synchronous with recovery in growth reduction and stimulation of AOX, NHX1 and SOS1 may emphasize the role of glycine in stimulating gene expression for raising wheat tolerance to NaCl.
Collapse
Affiliation(s)
- Enas G Badran
- Botany Department, Faculty of Science, Damietta University, Damietta, Egypt
| | | | | | | |
Collapse
|
117
|
Pinto E, Ferreira IMPLVO. Cation transporters/channels in plants: Tools for nutrient biofortification. JOURNAL OF PLANT PHYSIOLOGY 2015; 179:64-82. [PMID: 25841207 DOI: 10.1016/j.jplph.2015.02.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/11/2015] [Accepted: 02/11/2015] [Indexed: 05/07/2023]
Abstract
Cation transporters/channels are key players in a wide range of physiological functions in plants, including cell signaling, osmoregulation, plant nutrition and metal tolerance. The recent identification of genes encoding some of these transport systems has allowed new studies toward further understanding of their integrated roles in plant. This review summarizes recent discoveries regarding the function and regulation of the multiple systems involved in cation transport in plant cells. The role of membrane transport in the uptake, distribution and accumulation of cations in plant tissues, cell types and subcellular compartments is described. We also discuss how the knowledge of inter- and intra-species variation in cation uptake, transport and accumulation as well as the molecular mechanisms responsible for these processes can be used to increase nutrient phytoavailability and nutrients accumulation in the edible tissues of plants. The main trends for future research in the field of biofortification are proposed.
Collapse
Affiliation(s)
- Edgar Pinto
- REQUIMTE/Department of Chemical Sciences, Laboratory of Bromatology and Hydrology, Faculty of Pharmacy - University of Porto, Portugal; CISA - Research Centre on Environment and Health, School of Allied Health Sciences, Polytechnic Institute of Porto, Portugal.
| | - Isabel M P L V O Ferreira
- REQUIMTE/Department of Chemical Sciences, Laboratory of Bromatology and Hydrology, Faculty of Pharmacy - University of Porto, Portugal
| |
Collapse
|
118
|
Xu H, Martinoia E, Szabo I. Organellar channels and transporters. Cell Calcium 2015; 58:1-10. [PMID: 25795199 DOI: 10.1016/j.ceca.2015.02.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 02/20/2015] [Indexed: 12/22/2022]
Abstract
Decades of intensive research have led to the discovery of most plasma membrane ion channels and transporters and the characterization of their physiological functions. In contrast, although over 80% of transport processes occur inside the cells, the ion flux mechanisms across intracellular membranes (the endoplasmic reticulum, Golgi apparatus, endosomes, lysosomes, mitochondria, chloroplasts, and vacuoles) are difficult to investigate and remain poorly understood. Recent technical advances in super-resolution microscopy, organellar electrophysiology, organelle-targeted fluorescence imaging, and organelle proteomics have pushed a large step forward in the research of intracellular ion transport. Many new organellar channels are molecularly identified and electrophysiologically characterized. Additionally, molecular identification of many of these ion channels/transporters has made it possible to study their physiological functions by genetic and pharmacological means. For example, organellar channels have been shown to regulate important cellular processes such as programmed cell death and photosynthesis, and are involved in many different pathologies. This special issue (SI) on organellar channels and transporters aims to provide a forum to discuss the recent advances and to define the standard and open questions in this exciting and rapidly developing field. Along this line, a new Gordon Research Conference dedicated to the multidisciplinary study of intracellular membrane transport proteins will be launched this coming summer.
Collapse
Affiliation(s)
- Haoxing Xu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 3089 Natural Science Building (Kraus), 830 North University Avenue, Ann Arbor, MI 48109-1048, USA.
| | - Enrico Martinoia
- Institute of Plant Biology, University of Zürich, Zollikerstr. 107, CH-8008 Zürich, Switzerland.
| | - Ildiko Szabo
- Department of Biology, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy; CNR Neuroscience Institute, Viale G. Colombo 3, 35121 Padova, Italy.
| |
Collapse
|
119
|
Snowden CJ, Thomas B, Baxter CJ, Smith JAC, Sweetlove LJ. A tonoplast Glu/Asp/GABA exchanger that affects tomato fruit amino acid composition. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 81:651-60. [PMID: 25602029 PMCID: PMC4950293 DOI: 10.1111/tpj.12766] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 12/16/2014] [Accepted: 12/23/2014] [Indexed: 05/18/2023]
Abstract
Vacuolar accumulation of acidic metabolites is an important aspect of tomato fruit flavour and nutritional quality. The amino acids Asp and Glu accumulate to high concentrations during ripening, while γ-aminobutyrate (GABA) shows an approximately stoichiometric decline. Given that GABA can be catabolised to form Glu and subsequently Asp, and the requirement for the fruit to maintain osmotic homeostasis during ripening, we hypothesised the existence of a tonoplast transporter that exports GABA from the vacuole in exchange for import of either Asp or Glu. We show here that the tomato vacuolar membrane possesses such a transport property: transport of Glu across isolated tonoplast vesicle membranes was trans-stimulated in counterexchange mode by GABA, Glu and Asp. We identified SlCAT9 as a candidate protein for this exchanger using quantitative proteomics of a tonoplast-enriched membrane fraction. Transient expression of a SlCAT9-YFP fusion in tobacco confirmed a tonoplast localisation. The function of the protein was examined by overexpression of SlCAT9 in transgenic tomato plants. Tonoplast vesicles isolated from transgenic plants showed higher rates of Glu and GABA transport than wild-type (WT) only when assayed in counterexchange mode with Glu, Asp, or GABA. Moreover, there were substantial increases in the content of all three cognate amino acids in ripe fruit from the transgenic plants. We conclude that SlCAT9 is a tonoplast Glu/Asp/GABA exchanger that strongly influences the accumulation of these amino acids during fruit development.
Collapse
Affiliation(s)
- Christopher J Snowden
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| | | | | | | | | |
Collapse
|
120
|
Jung B, Ludewig F, Schulz A, Meißner G, Wöstefeld N, Flügge UI, Pommerrenig B, Wirsching P, Sauer N, Koch W, Sommer F, Mühlhaus T, Schroda M, Cuin TA, Graus D, Marten I, Hedrich R, Neuhaus HE. Identification of the transporter responsible for sucrose accumulation in sugar beet taproots. NATURE PLANTS 2015; 1:14001. [PMID: 27246048 DOI: 10.1038/nplants.2014.1] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 09/24/2014] [Indexed: 05/21/2023]
Abstract
Sugar beet provides around one third of the sugar consumed worldwide and serves as a significant source of bioenergy in the form of ethanol. Sucrose accounts for up to 18% of plant fresh weight in sugar beet. Most of the sucrose is concentrated in the taproot, where it accumulates in the vacuoles. Despite 30 years of intensive research, the transporter that facilitates taproot sucrose accumulation has escaped identification. Here, we combine proteomic analyses of the taproot vacuolar membrane, the tonoplast, with electrophysiological analyses to show that the transporter BvTST2.1 is responsible for vacuolar sucrose uptake in sugar beet taproots. We show that BvTST2.1 is a sucrose-specific transporter, and present evidence to suggest that it operates as a proton antiporter, coupling the import of sucrose into the vacuole to the export of protons. BvTST2.1 exhibits a high amino acid sequence similarity to members of the tonoplast monosaccharide transporter family in Arabidopsis, prompting us to rename this group of proteins 'tonoplast sugar transporters'. The identification of BvTST2.1 could help to increase sugar yields from sugar beet and other sugar-storing plants in future breeding programs.
Collapse
Affiliation(s)
- Benjamin Jung
- Pflanzenphysiologie, University Kaiserslautern, Erwin Schrödinger Straße, D-67653 Kaiserslautern, Germany
| | - Frank Ludewig
- Biocenter Cologne, Botanical Institute II and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Zülpicher Straße 47b, D-50674, Germany
| | - Alexander Schulz
- Biophysics and Molecular Plant Physiology, University Würzburg, Julius von Sachs Platz 2, D-97082 Würzburg, Germany
| | - Garvin Meißner
- Pflanzenphysiologie, University Kaiserslautern, Erwin Schrödinger Straße, D-67653 Kaiserslautern, Germany
| | - Nicole Wöstefeld
- Biocenter Cologne, Botanical Institute II and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Zülpicher Straße 47b, D-50674, Germany
| | - Ulf-Ingo Flügge
- Biocenter Cologne, Botanical Institute II and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Zülpicher Straße 47b, D-50674, Germany
| | - Benjamin Pommerrenig
- Molecular Plant Physiology, University Erlangen-Nuremberg, Staudtstraße 5, D-91058 Erlangen, Germany
| | - Petra Wirsching
- Molecular Plant Physiology, University Erlangen-Nuremberg, Staudtstraße 5, D-91058 Erlangen, Germany
| | - Norbert Sauer
- Molecular Plant Physiology, University Erlangen-Nuremberg, Staudtstraße 5, D-91058 Erlangen, Germany
| | - Wolfgang Koch
- KWS Saat AG, Grimsehlstr.31, D37555 Einbeck, Germany
| | - Frederik Sommer
- Molecular Biotechnology and Systems Biology, University Kaiserslautern, Paul-Ehrlich-Straße, D-67653 Kaiserslautern Germany
| | - Timo Mühlhaus
- Molecular Biotechnology and Systems Biology, University Kaiserslautern, Paul-Ehrlich-Straße, D-67653 Kaiserslautern Germany
| | - Michael Schroda
- Molecular Biotechnology and Systems Biology, University Kaiserslautern, Paul-Ehrlich-Straße, D-67653 Kaiserslautern Germany
| | - Tracey Ann Cuin
- Biophysics and Molecular Plant Physiology, University Würzburg, Julius von Sachs Platz 2, D-97082 Würzburg, Germany
| | - Dorothea Graus
- Biophysics and Molecular Plant Physiology, University Würzburg, Julius von Sachs Platz 2, D-97082 Würzburg, Germany
| | - Irene Marten
- Biophysics and Molecular Plant Physiology, University Würzburg, Julius von Sachs Platz 2, D-97082 Würzburg, Germany
| | - Rainer Hedrich
- Biophysics and Molecular Plant Physiology, University Würzburg, Julius von Sachs Platz 2, D-97082 Würzburg, Germany
| | - H Ekkehard Neuhaus
- Pflanzenphysiologie, University Kaiserslautern, Erwin Schrödinger Straße, D-67653 Kaiserslautern, Germany
| |
Collapse
|
121
|
Guilbaud CSE, Dalchau N, Purves DW, Turnbull LA. Is 'peak N' key to understanding the timing of flowering in annual plants? THE NEW PHYTOLOGIST 2015; 205:918-927. [PMID: 25298111 DOI: 10.1111/nph.13095] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 08/08/2014] [Indexed: 06/04/2023]
Abstract
Flowering time in annual plants has large fitness consequences and has been the focus of theoretical and empirical study. Previous theory has concluded that flowering time has evolved over evolutionary time to maximize fitness over a particular season length. We introduce a new model where flowering is cued by a growth-rate rule (peak nitrogen (N)). Flowering is therefore sensitive to physiological parameters and to current environmental conditions, including N availability and the presence of competitors. The model predicts that, when overall conditions are suitable for flowering, plants should never flower after 'peak N', the point during development when the whole-plant N uptake rate reaches its maximum. Our model further predicts correlations between flowering time and vegetative growth rates, and that the response to increased N depends heavily on how this extra N is made available. We compare our predictions to observations in the literature. We suggest that annual plants may have evolved to use growth-rate rules as part of the cue for flowering, allowing them to smoothly and optimally adjust their flowering time to a wide range of local conditions. If so, there are widespread implications for the study of the molecular biology behind flowering pathways.
Collapse
Affiliation(s)
- Camille S E Guilbaud
- Institute of Evolutionary Biology and Environmental Sciences, University of Zurich, Zurich, CH-8057, Switzerland
| | | | | | | |
Collapse
|
122
|
Schumacher K. pH in the plant endomembrane system-an import and export business. CURRENT OPINION IN PLANT BIOLOGY 2014; 22:71-76. [PMID: 25282587 DOI: 10.1016/j.pbi.2014.09.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 09/11/2014] [Accepted: 09/12/2014] [Indexed: 05/06/2023]
Abstract
pH homeostasis is an essential process in all plant cells and the maintenance of correct luminal pH in the compartments of the endomembrane system is important not only for secondary active transport but also for a variety of cellular functions including protein modification, sorting, and trafficking. Due to their electrogenicity primary H(+)-pumps cannot establish and control the often large proton-gradients single-handedly but require the co-action of other ion transporters that serve as either shunt conductances or proton-leaks. Here, I will thus focus on recent results that highlight the interplay of proton-pumps and proton-coupled transporters in controlling pH in the compartments of the plant endomembrane system.
Collapse
Affiliation(s)
- Karin Schumacher
- Dep. of Cell Biology, Centre for Organismal Studies (COS), Universität Heidelberg, 69120 Heidelberg, Germany.
| |
Collapse
|
123
|
Neuhaus HE, Trentmann O. Regulation of transport processes across the tonoplast. FRONTIERS IN PLANT SCIENCE 2014; 5:460. [PMID: 25309559 PMCID: PMC4160088 DOI: 10.3389/fpls.2014.00460] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 08/26/2014] [Indexed: 05/24/2023]
Abstract
In plants, the vacuole builds up the cellular turgor and represents an important component in cellular responses to diverse stress stimuli. Rapid volume changes of cells, particularly of motor cells, like guard cells, are caused by variation of osmolytes and consequently of the water contents in the vacuole. Moreover, directed solute uptake into or release out of the large central vacuole allows adaptation of cytosolic metabolite levels according to the current physiological requirements and specific cellular demands. Therefore, solute passage across the vacuolar membrane, the tonoplast, has to be tightly regulated. Important principles in vacuolar transport regulation are changes of tonoplast transport protein abundances by differential expression of genes or changes of their activities, e.g., due to post-translational modification or by interacting proteins. Because vacuolar transport is in most cases driven by an electro-chemical gradient altered activities of tonoplast proton pumps significantly influence vacuolar transport capacities. Intense studies on individual tonoplast proteins but also unbiased system biological approaches have provided important insights into the regulation of vacuolar transport. This short review refers to selected examples of tonoplast proteins and their regulation, with special focus on protein phosphorylation.
Collapse
Affiliation(s)
| | - Oliver Trentmann
- *Correspondence: Oliver Trentmann, Plant Physiology, Department of Biology, Technische Universität Kaiserslautern, Postfach 3049, Kaiserslautern D-67653, Germany e-mail:
| |
Collapse
|
124
|
Patrick JW, Colyvas K. Crop yield components - photoassimilate supply- or utilisation limited-organ development? FUNCTIONAL PLANT BIOLOGY : FPB 2014; 41:893-913. [PMID: 32481043 DOI: 10.1071/fp14048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 04/18/2014] [Indexed: 06/11/2023]
Abstract
Yield potential is the genome-encoded capacity of a crop species to generate yield in an optimal growth environment. Ninety per cent of plant biomass is derived from the photosynthetic reduction of carbon dioxide to organic carbon (photoassimilates - primarily sucrose). Thus, development of yield components (organ numbers and individual organ masses) can be limited by photoassimilate supply (photosynthesis arranged in series with phloem transport) or by their inherent capacity to utilise imported photoassimilates for growth or storage. To this end, photoassimilate supply/utilisation of crop yield has been quantitatively re-evaluated using published responses of yield components to elevated carbon dioxide concentrations across a selection of key crop species including cereal and pulse grains, fleshy fruits, tubers and sugar storing stems and tap roots. The analysis demonstrates that development of harvested organ numbers is strongly limited by photoassimilate supply. Vegetative branching and, to a lesser extent, flower/pod/fleshy fruit abortion, are the major yield components contributing to sensitivity of organ numbers to photoassimilate supply. In contrast, harvested organ size is partially dependent (eudicots), or completely independent (cereals), of photoassimilate supply. Processes limiting photoassimilate utilisation by harvested organs include membrane transport of soluble sugars and their allocation into polymeric storage products.
Collapse
Affiliation(s)
- John W Patrick
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Kim Colyvas
- School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
| |
Collapse
|
125
|
Zhang J, Martinoia E, De Angeli A. Cytosolic nucleotides block and regulate the Arabidopsis vacuolar anion channel AtALMT9. J Biol Chem 2014; 289:25581-9. [PMID: 25028514 DOI: 10.1074/jbc.m114.576108] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The aluminum-activated malate transporters (ALMTs) form a membrane protein family exhibiting different physiological roles in plants, varying from conferring tolerance to environmental Al(3+) to the regulation of stomatal movement. The regulation of the anion channels of the ALMT family is largely unknown. Identifying intracellular modulators of the activity of anion channels is fundamental to understanding their physiological functions. In this study we investigated the role of cytosolic nucleotides in regulating the activity of the vacuolar anion channel AtALMT9. We found that cytosolic nucleotides modulate the transport activity of AtALMT9. This modulation was based on a direct block of the pore of the channel at negative membrane potentials (open channel block) by the nucleotide and not by a phosphorylation mechanism. The block by nucleotides of AtALMT9-mediated currents was voltage dependent. The blocking efficiency of intracellular nucleotides increased with the number of phosphate groups and ATP was the most effective cellular blocker. Interestingly, the ATP block induced a marked modification of the current-voltage characteristic of AtALMT9. In addition, increased concentrations of vacuolar anions were able to shift the ATP block threshold to a more negative membrane potential. The block of AtALMT9-mediated anion currents by ATP at negative membrane potentials acts as a gate of the channel and vacuolar anion tune this gating mechanism. Our results suggest that anion transport across the vacuolar membrane in plant cells is controlled by cytosolic nucleotides and the energetic status of the cell.
Collapse
Affiliation(s)
- Jingbo Zhang
- From the Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland and
| | - Enrico Martinoia
- From the Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland and
| | - Alexis De Angeli
- From the Institute of Plant Biology, University of Zurich, CH-8008 Zurich, Switzerland and the Institut des Sciences du Végétal, CNRS, 91198 Gif-sur-Yvette, France
| |
Collapse
|
126
|
Kollist H, Nuhkat M, Roelfsema MRG. Closing gaps: linking elements that control stomatal movement. THE NEW PHYTOLOGIST 2014; 203:44-62. [PMID: 24800691 DOI: 10.1111/nph.12832] [Citation(s) in RCA: 186] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 03/27/2014] [Indexed: 05/18/2023]
Abstract
Stomata are an attractive experimental system in plant biology, because the responses of guard cells to environmental signals can be directly linked to changes in the aperture of stomatal pores. In this review, the mechanics of stomatal movement are discussed in relation to ion transport in guard cells. Emphasis is placed on the ion pumps, transporters, and channels in the plasma membrane, as well as in the vacuolar membrane. The biophysical properties of transport proteins for H(+), K(+), Ca(2+), and anions are discussed and related to their function in guard cells during stomatal movements. Guard cell signaling pathways for ABA, CO2, ozone, microbe-associated molecular patterns (MAMPs) and blue light are presented. Special attention is given to the regulation of the slow anion channel (SLAC) and SLAC homolog (SLAH)-type anion channels by the ABA signalosome. Over the last decade, several knowledge gaps in the regulation of ion transport in guard cells have been closed. The current state of knowledge is an excellent starting point for tackling important open questions concerning stress tolerance in plants.
Collapse
Affiliation(s)
- Hannes Kollist
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia
| | | | | |
Collapse
|
127
|
Graham NS, Hammond JP, Lysenko A, Mayes S, O Lochlainn S, Blasco B, Bowen HC, Rawlings CJ, Rios JJ, Welham S, Carion PWC, Dupuy LX, King GJ, White PJ, Broadley MR. Genetical and comparative genomics of Brassica under altered Ca supply identifies Arabidopsis Ca-transporter orthologs. THE PLANT CELL 2014; 26:2818-30. [PMID: 25082855 PMCID: PMC4145116 DOI: 10.1105/tpc.114.128603] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 06/09/2014] [Accepted: 07/14/2014] [Indexed: 05/18/2023]
Abstract
Although Ca transport in plants is highly complex, the overexpression of vacuolar Ca(2+) transporters in crops is a promising new technology to improve dietary Ca supplies through biofortification. Here, we sought to identify novel targets for increasing plant Ca accumulation using genetical and comparative genomics. Expression quantitative trait locus (eQTL) mapping to 1895 cis- and 8015 trans-loci were identified in shoots of an inbred mapping population of Brassica rapa (IMB211 × R500); 23 cis- and 948 trans-eQTLs responded specifically to altered Ca supply. eQTLs were screened for functional significance using a large database of shoot Ca concentration phenotypes of Arabidopsis thaliana. From 31 Arabidopsis gene identifiers tagged to robust shoot Ca concentration phenotypes, 21 mapped to 27 B. rapa eQTLs, including orthologs of the Ca(2+) transporters At-CAX1 and At-ACA8. Two of three independent missense mutants of BraA.cax1a, isolated previously by targeting induced local lesions in genomes, have allele-specific shoot Ca concentration phenotypes compared with their segregating wild types. BraA.CAX1a is a promising target for altering the Ca composition of Brassica, consistent with prior knowledge from Arabidopsis. We conclude that multiple-environment eQTL analysis of complex crop genomes combined with comparative genomics is a powerful technique for novel gene identification/prioritization.
Collapse
Affiliation(s)
- Neil S Graham
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom
| | - John P Hammond
- School of Agriculture, Policy, and Development, University of Reading, Earley Gate, Whiteknights, Reading RG6 6AR, United Kingdom
| | - Artem Lysenko
- Computational and Systems Biology Department, Rothamsted Research, West Common, Harpenden AL5 2JQ, United Kingdom
| | - Sean Mayes
- Crops for the Future Research Centre, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia
| | - Seosamh O Lochlainn
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom
| | - Bego Blasco
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom
| | - Helen C Bowen
- Warwick HRI, University of Warwick, Wellesbourne CV35 9EF, United Kingdom
| | - Chris J Rawlings
- Computational and Systems Biology Department, Rothamsted Research, West Common, Harpenden AL5 2JQ, United Kingdom
| | - Juan J Rios
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom
| | - Susan Welham
- Computational and Systems Biology Department, Rothamsted Research, West Common, Harpenden AL5 2JQ, United Kingdom
| | - Pierre W C Carion
- Computational and Systems Biology Department, Rothamsted Research, West Common, Harpenden AL5 2JQ, United Kingdom
| | - Lionel X Dupuy
- James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom
| | - Graham J King
- Southern Cross Plant Science, Southern Cross University, Lismore, New South Wales 2480, Australia
| | - Philip J White
- James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom College of Science, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia
| | - Martin R Broadley
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom
| |
Collapse
|
128
|
Ismail A, Takeda S, Nick P. Life and death under salt stress: same players, different timing? JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2963-79. [PMID: 24755280 DOI: 10.1093/jxb/eru159] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Salinity does not only stress plants but also challenges human life and the economy by posing severe constraints upon agriculture. To understand salt adaptation strategies of plants, it is central to extend agricultural production to salt-affected soils. Despite high impact and intensive research, it has been difficult to dissect the plant responses to salt stress and to define the decisive key factors for the outcome of salinity signalling. To connect the rapidly accumulating data from different systems, treatments, and organization levels (whole-plant, cellular, and molecular), and to identify the appropriate correlations among them, a clear conceptual framework is required. Similar to other stress responses, the molecular nature of the signals evoked after the onset of salt stress seems to be general, as with that observed in response to many other stimuli, and should not be considered to confer specificity per se. The focus of the current review is therefore on the temporal patterns of signals conveyed by molecules such as Ca(2+), H(+), reactive oxygen species, abscisic acid, and jasmonate. We propose that the outcome of the salinity response (adaptation versus cell death) depends on the timing with which these signals appear and disappear. In this context, the often-neglected non-selective cation channels are relevant. We also propose that constraining a given signal is as important as its induction, as it is the temporal competence of signalling (signal on demand) that confers specificity.
Collapse
Affiliation(s)
- Ahmed Ismail
- Department of Horticulture, Faculty of Agriculture, Damanhour University, Damanhour, Egypt
| | - Shin Takeda
- Bioscience and Biotechnology Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Peter Nick
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology (KIT), Germany
| |
Collapse
|
129
|
Eisenach C, Baetz U, Martinoia E. Vacuolar proton pumping: more than the sum of its parts? TRENDS IN PLANT SCIENCE 2014; 19:344-6. [PMID: 24703550 DOI: 10.1016/j.tplants.2014.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 03/12/2014] [Accepted: 03/18/2014] [Indexed: 05/21/2023]
Abstract
Petunia flower colour is dependent on vacuolar pH and is therefore used to study acidification mechanisms. Recently, it was shown that the concerted action of two tonoplast-localised P3-ATPases is required to hyperacidify vacuoles of petunia petal epidermis cells. Here we discuss how steep cross-tonoplast pH gradients may be established in specific cells.
Collapse
Affiliation(s)
- Cornelia Eisenach
- Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
| | - Ulrike Baetz
- Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Enrico Martinoia
- Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| |
Collapse
|
130
|
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.
Collapse
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
| |
Collapse
|
131
|
Ranocha P, Dima O, Nagy R, Felten J, Corratgé-Faillie C, Novák O, Morreel K, Lacombe B, Martinez Y, Pfrunder S, Jin X, Renou JP, Thibaud JB, Ljung K, Fischer U, Martinoia E, Boerjan W, Goffner D. Arabidopsis WAT1 is a vacuolar auxin transport facilitator required for auxin homoeostasis. Nat Commun 2014; 4:2625. [PMID: 24129639 PMCID: PMC3826630 DOI: 10.1038/ncomms3625] [Citation(s) in RCA: 186] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 09/17/2013] [Indexed: 01/24/2023] Open
Abstract
The plant hormone auxin (indole-3-acetic acid, IAA) has a crucial role in plant development. Its spatiotemporal distribution is controlled by a combination of biosynthetic, metabolic and transport mechanisms. Four families of auxin transporters have been identified that mediate transport across the plasma or endoplasmic reticulum membrane. Here we report the discovery and the functional characterization of the first vacuolar auxin transporter. We demonstrate that WALLS ARE THIN1 (WAT1), a plant-specific protein that dictates secondary cell wall thickness of wood fibres, facilitates auxin export from isolated Arabidopsis vacuoles in yeast and in Xenopus oocytes. We unambiguously identify IAA and related metabolites in isolated Arabidopsis vacuoles, suggesting a key role for the vacuole in intracellular auxin homoeostasis. Moreover, local auxin application onto wat1 mutant stems restores fibre cell wall thickness. Our study provides new insight into the complexity of auxin transport in plants and a means to dissect auxin function during fibre differentiation.
Collapse
Affiliation(s)
- Philippe Ranocha
- 1] Université de Toulouse; UPS; UMR 5546, Laboratoire de Recherche en Sciences Végétales; BP 42617, F-31326, Castanet-Tolosan, France [2] Centre National de la Recherche Scientifique; CNRS; UMR5546; Laboratoire de Recherche en Sciences Végétales; BP 42617, F-31326, Castanet-Tolosan, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
132
|
Andrés Z, Pérez-Hormaeche J, Leidi EO, Schlücking K, Steinhorst L, McLachlan DH, Schumacher K, Hetherington AM, Kudla J, Cubero B, Pardo JM. Control of vacuolar dynamics and regulation of stomatal aperture by tonoplast potassium uptake. Proc Natl Acad Sci U S A 2014; 111:E1806-14. [PMID: 24733919 PMCID: PMC4035970 DOI: 10.1073/pnas.1320421111] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Stomatal movements rely on alterations in guard cell turgor. This requires massive K(+) bidirectional fluxes across the plasma and tonoplast membranes. Surprisingly, given their physiological importance, the transporters mediating the energetically uphill transport of K(+) into the vacuole remain to be identified. Here, we report that, in Arabidopsis guard cells, the tonoplast-localized K(+)/H(+) exchangers NHX1 and NHX2 are pivotal in the vacuolar accumulation of K(+) and that nhx1 nhx2 mutant lines are dysfunctional in stomatal regulation. Hypomorphic and complete-loss-of-function double mutants exhibited significantly impaired stomatal opening and closure responses. Disruption of K(+) accumulation in guard cells correlated with more acidic vacuoles and the disappearance of the highly dynamic remodelling of vacuolar structure associated with stomatal movements. Our results show that guard cell vacuolar accumulation of K(+) is a requirement for stomatal opening and a critical component in the overall K(+) homeostasis essential for stomatal closure, and suggest that vacuolar K(+) fluxes are also of decisive importance in the regulation of vacuolar dynamics and luminal pH that underlie stomatal movements.
Collapse
Affiliation(s)
- Zaida Andrés
- Instituto de Recursos Naturales y Agrobiologia de Sevilla, Consejo Superior de Investigaciones Cientificas, 41012 Seville, Spain
| | - Javier Pérez-Hormaeche
- Instituto de Recursos Naturales y Agrobiologia de Sevilla, Consejo Superior de Investigaciones Cientificas, 41012 Seville, Spain
| | - Eduardo O. Leidi
- Instituto de Recursos Naturales y Agrobiologia de Sevilla, Consejo Superior de Investigaciones Cientificas, 41012 Seville, Spain
| | - Kathrin Schlücking
- Institut für Biologie und Biotechnologie der Pflanzen, Universität Münster, 48149 Münster, Germany
| | - Leonie Steinhorst
- Institut für Biologie und Biotechnologie der Pflanzen, Universität Münster, 48149 Münster, Germany
| | - Deirdre H. McLachlan
- School of Biological Sciences, University of Bristol, Bristol BS8 1UG, United Kingdom; and
| | - Karin Schumacher
- Centre for Organismal Studies, Universität Heidelberg, 69120 Heidelberg, Germany
| | | | - Jörg Kudla
- Institut für Biologie und Biotechnologie der Pflanzen, Universität Münster, 48149 Münster, Germany
| | - Beatriz Cubero
- Instituto de Recursos Naturales y Agrobiologia de Sevilla, Consejo Superior de Investigaciones Cientificas, 41012 Seville, Spain
| | - José M. Pardo
- Instituto de Recursos Naturales y Agrobiologia de Sevilla, Consejo Superior de Investigaciones Cientificas, 41012 Seville, Spain
| |
Collapse
|
133
|
Klemens PAW, Patzke K, Trentmann O, Poschet G, Büttner M, Schulz A, Marten I, Hedrich R, Neuhaus HE. Overexpression of a proton-coupled vacuolar glucose exporter impairs freezing tolerance and seed germination. THE NEW PHYTOLOGIST 2014; 202:188-197. [PMID: 24329902 DOI: 10.1111/nph.12642] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 11/13/2013] [Indexed: 05/18/2023]
Abstract
Arabidopsis vacuoles harbor, besides sugar transporter of the TMT-type, an early response to dehydration like 6 (ERDL6) protein involved in glucose export into the cytosol. However, the mode of transport of ERDL6 and the plant's feedback to overexpression of its activity on essential properties such as, for example, seed germination or freezing tolerance, remain unexplored. Using patch-clamp studies on vacuoles expressing AtERDL6 we demonstrated directly that this carrier operates as a proton-driven glucose exporter. Overexpression of BvIMP, the closest sugar beet (Beta vulgaris) homolog to AtERDL6, in Arabidopsis leads surprisingly to impaired seed germination under both conditions, sugar application and low environmental temperatures, but not under standard conditions. Upon cold treatment, BvIMP overexpressor plants accumulated lower quantities of monosaccharides than the wild-type, a response in line with the reduced frost tolerance of the transgenic Arabidopsis plants, and the fact that cold temperatures inhibits BvIMP transcription in sugar beet leaves. With these findings we show that the tight control of vacuolar sugar import and export is a key requisite for cold tolerance and seed germination of plants.
Collapse
Affiliation(s)
- Patrick A W Klemens
- Plant Physiology, University of Kaiserslautern, Erwin-Schrödinger-Str., D-67653, Kaiserslautern, Germany
| | - Kathrin Patzke
- Plant Physiology, University of Kaiserslautern, Erwin-Schrödinger-Str., D-67653, Kaiserslautern, Germany
| | - Oliver Trentmann
- Plant Physiology, University of Kaiserslautern, Erwin-Schrödinger-Str., D-67653, Kaiserslautern, Germany
| | - Gernot Poschet
- Centre for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 360, 69120, Heidelberg, Germany
| | - Michael Büttner
- Centre for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 360, 69120, Heidelberg, Germany
| | - Alexander Schulz
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany
| | - Irene Marten
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany
| | - Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany
| | - H Ekkehard Neuhaus
- Plant Physiology, University of Kaiserslautern, Erwin-Schrödinger-Str., D-67653, Kaiserslautern, Germany
| |
Collapse
|
134
|
Barkla BJ, Vera-Estrella R, Pantoja O. Progress and challenges for abiotic stress proteomics of crop plants. Proteomics 2014; 13:1801-15. [PMID: 23512887 DOI: 10.1002/pmic.201200401] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 01/07/2013] [Accepted: 01/08/2013] [Indexed: 12/12/2022]
Abstract
Plants are continually challenged to recognize and respond to adverse changes in their environment to avoid detrimental effects on growth and development. Understanding the mechanisms that crop plants employ to resist and tolerate abiotic stress is of considerable interest for designing agriculture breeding strategies to ensure sustainable productivity. The application of proteomics technologies to advance our knowledge in crop plant abiotic stress tolerance has increased dramatically in the past few years as evidenced by the large amount of publications in this area. This is attributed to advances in various technology platforms associated with MS-based techniques as well as the accessibility of proteomics units to a wider plant research community. This review summarizes the work which has been reported for major crop plants and evaluates the findings in context of the approaches that are widely employed with the aim to encourage broadening the strategies used to increase coverage of the proteome.
Collapse
Affiliation(s)
- Bronwyn J Barkla
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
| | | | | |
Collapse
|
135
|
Hermans C, Conn SJ, Chen J, Xiao Q, Verbruggen N. An update on magnesium homeostasis mechanisms in plants. Metallomics 2014; 5:1170-83. [PMID: 23420558 DOI: 10.1039/c3mt20223b] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Worldwide, nearly two-thirds of the population do not consume the recommended amount of magnesium (Mg) in their diet. Furthermore, low Mg status (hypomagnesaemia) is known to contribute to a number of human chronic disease conditions. Because the principal dietary Mg source is of plant origin, agronomic and genetic biofortification strategies are aimed at improving nutritional Mg content in food crops to overcome this mineral deficiency in humans. This update incorporates the contributions of annotated permeases involved in Mg uptake, storage and recycling with a schematic model of Mg movement at the organ and cellular levels in the model species Arabidopsis thaliana. Furthermore, approaches using mutagenesis or natural ionomic variation to identify loci involved in Mg homeostasis in roots, leaves and seeds will be summarised. A brief overview will be presented on how Arabidopsis research can help to develop strategies for biofortification of crops.
Collapse
Affiliation(s)
- Christian Hermans
- Laboratory of Plant Physiology and Molecular Genetics, Université Libre de Bruxelles, Campus Plaine CP 242, Bd du Triomphe, 1050 Brussels, Belgium.
| | | | | | | | | |
Collapse
|
136
|
Tohge T, Fernie AR. Lignin, mitochondrial family, and photorespiratory transporter classification as case studies in using co-expression, co-response, and protein locations to aid in identifying transport functions. FRONTIERS IN PLANT SCIENCE 2014; 5:75. [PMID: 24672529 PMCID: PMC3955873 DOI: 10.3389/fpls.2014.00075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 02/17/2014] [Indexed: 06/03/2023]
Abstract
Whole genome sequencing and the relative ease of transcript profiling have facilitated the collection and data warehousing of immense quantities of expression data. However, a substantial proportion of genes are not yet functionally annotated a problem which is particularly acute for transport proteins. In Arabidopsis, for example, only a minor fraction of the estimated 700 intracellular transporters have been identified at the molecular genetic level. Furthermore it is only within the last couple of years that critical genes such as those encoding the final transport step required for the long distance transport of sucrose and the first transporter of the core photorespiratory pathway have been identified. Here we will describe how transcriptional coordination between genes of known function and non-annotated genes allows the identification of putative transporters on the premise that such co-expressed genes tend to be functionally related. We will additionally extend this to include the expansion of this approach to include phenotypic information from other levels of cellular organization such as proteomic and metabolomic data and provide case studies wherein this approach has successfully been used to fill knowledge gaps in important metabolic pathways and physiological processes.
Collapse
Affiliation(s)
- Takayuki Tohge
- *Correspondence: Takayuki Tohge, Department 1 (Willmitzer), Central Metabolism, Max Planck Institute for Plant Physiology, Am Mühlenberg 1, 14476 Potsdam, Germany e-mail:
| | | |
Collapse
|
137
|
Keller M, Shrestha PM. Solute accumulation differs in the vacuoles and apoplast of ripening grape berries. PLANTA 2014; 239:633-42. [PMID: 24310282 DOI: 10.1007/s00425-013-2004-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 11/25/2013] [Indexed: 05/20/2023]
Abstract
Phloem unloading is thought to switch from a symplastic route to an apoplastic route at the beginning of ripening in grape berries and some other fleshy fruits. However, it is unclear whether different solutes accumulate in both the mesocarp vacuoles and the apoplast. We modified a method developed for tomato fruit to extract apoplastic sap from grape berries and measured the changes in apoplastic and vacuolar pH, soluble sugars, organic acids, and potassium in ripening berries of Vitis vinifera 'Merlot' and V. labruscana 'Concord'. Solute accumulation varied by genotype, compartment, and chemical species. The apoplast pH was substantially higher than the vacuolar pH, especially in Merlot (approximately two units). However, the vacuole-apoplast proton gradient declined during ripening and in Merlot, but not in Concord, collapsed entirely at maturity. Hexoses accumulated in both the vacuoles and apoplast but at different rates. Organic acids, especially malate, declined much more in the vacuoles than in the apoplast. Potassium accumulated in the vacuoles and apoplast of Merlot. In Concord, by contrast, potassium increased in the vacuoles but decreased in the apoplast. These results suggest that solutes in the fruit apoplast are tightly regulated and under developmental control.
Collapse
Affiliation(s)
- Markus Keller
- Irrigated Agriculture Research and Extension Center, Washington State University, 24106 N. Bunn Rd., Prosser, WA, 99350, USA,
| | | |
Collapse
|
138
|
Guo WJ, Nagy R, Chen HY, Pfrunder S, Yu YC, Santelia D, Frommer WB, Martinoia E. SWEET17, a facilitative transporter, mediates fructose transport across the tonoplast of Arabidopsis roots and leaves. PLANT PHYSIOLOGY 2014; 164:777-89. [PMID: 24381066 PMCID: PMC3912105 DOI: 10.1104/pp.113.232751] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 12/29/2013] [Indexed: 05/18/2023]
Abstract
Fructose (Fru) is a major storage form of sugars found in vacuoles, yet the molecular regulation of vacuolar Fru transport is poorly studied. Although SWEET17 (for SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTERS17) has been characterized as a vacuolar Fru exporter in leaves, its expression in leaves is low. Here, RNA analysis and SWEET17-β-glucuronidase/-GREEN FLUORESCENT PROTEIN fusions expressed in Arabidopsis (Arabidopsis thaliana) reveal that SWEET17 is highly expressed in the cortex of roots and localizes to the tonoplast of root cells. Expression of SWEET17 in roots was inducible by Fru and darkness, treatments that activate accumulation and release of vacuolar Fru, respectively. Mutation and ectopic expression of SWEET17 led to increased and decreased root growth in the presence of Fru, respectively. Overexpression of SWEET17 specifically reduced the Fru content in leaves by 80% during cold stress. These results intimate that SWEET17 functions as a Fru-specific uniporter on the root tonoplast. Vacuoles overexpressing SWEET17 showed increased [14C]Fru uptake compared with the wild type. SWEET17-mediated Fru uptake was insensitive to ATP or treatment with NH4Cl or carbonyl cyanide m-chlorophenyl hydrazone, indicating that SWEET17 functions as an energy-independent facilitative carrier. The Arabidopsis genome contains a close paralog of SWEET17 in clade IV, SWEET16. The predominant expression of SWEET16 in root vacuoles and reduced root growth of mutants under Fru excess indicate that SWEET16 also functions as a vacuolar transporter in roots. We propose that in addition to a role in leaves, SWEET17 plays a key role in facilitating bidirectional Fru transport across the tonoplast of roots in response to metabolic demand to maintain cytosolic Fru homeostasis.
Collapse
|
139
|
Gigolashvili T, Kopriva S. Transporters in plant sulfur metabolism. FRONTIERS IN PLANT SCIENCE 2014; 5:442. [PMID: 25250037 PMCID: PMC4158793 DOI: 10.3389/fpls.2014.00442] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 08/18/2014] [Indexed: 05/02/2023]
Abstract
Sulfur is an essential nutrient, necessary for synthesis of many metabolites. The uptake of sulfate, primary and secondary assimilation, the biosynthesis, storage, and final utilization of sulfur (S) containing compounds requires a lot of movement between organs, cells, and organelles. Efficient transport systems of S-containing compounds across the internal barriers or the plasma membrane and organellar membranes are therefore required. Here, we review a current state of knowledge of the transport of a range of S-containing metabolites within and between the cells as well as of their long distance transport. An improved understanding of mechanisms and regulation of transport will facilitate successful engineering of the respective pathways, to improve the plant yield, biotic interaction and nutritional properties of crops.
Collapse
Affiliation(s)
- Tamara Gigolashvili
- Department of Plant Molecular Physiology, Botanical Institute and Cluster of Excellence on Plant Sciences, Cologne Biocenter, University of CologneCologne Germany
- *Correspondence: Tamara Gigolashvili, Department of Plant Molecular Physiology, Botanical Institute and Cluster of Excellence on Plant Sciences, Cologne Biocenter, University of Cologne, Zülpicher Street 47 B, 50674 Cologne, Germany e-mail:
| | - Stanislav Kopriva
- Plant Biochemistry Department, Botanical Institute and Cluster of Excellence on Plant Sciences, Cologne Biocenter, University of CologneCologne Germany
| |
Collapse
|
140
|
Peng JS, Gong JM. Vacuolar sequestration capacity and long-distance metal transport in plants. FRONTIERS IN PLANT SCIENCE 2014; 5:19. [PMID: 24550927 PMCID: PMC3912839 DOI: 10.3389/fpls.2014.00019] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 01/15/2014] [Indexed: 05/02/2023]
Abstract
The vacuole is a pivotal organelle functioning in storage of metabolites, mineral nutrients, and toxicants in higher plants. Accumulating evidence indicates that in addition to its storage role, the vacuole contributes essentially to long-distance transport of metals, through the modulation of Vacuolar sequestration capacity (VSC) which is shown to be primarily controlled by cytosolic metal chelators and tonoplast-localized transporters, or the interaction between them. Plants adapt to their environments by dynamic regulation of VSC for specific metals and hence targeting metals to specific tissues. Study of VSC provides not only a new angle to understand the long-distance root-to-shoot transport of minerals in plants, but also an efficient way to biofortify essential mineral nutrients or to phytoremediate non-essential metal pollution. The current review will focus on the most recent proceedings on the interaction mechanisms between VSC regulation and long-distance metal transport.
Collapse
Affiliation(s)
- Jia-Shi Peng
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China
- National Center for Gene Research, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China
| | - Ji-Ming Gong
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China
- National Center for Gene Research, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China
- *Correspondence: Ji-Ming Gong, National Key Laboratory of Plant Molecular Genetics and National Center for Gene Research, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China e-mail:
| |
Collapse
|
141
|
AtALMT9 is a malate-activated vacuolar chloride channel required for stomatal opening in Arabidopsis. Nat Commun 2013; 4:1804. [PMID: 23653216 PMCID: PMC3644109 DOI: 10.1038/ncomms2815] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 03/27/2013] [Indexed: 01/30/2023] Open
Abstract
Water deficit strongly affects crop productivity. Plants control water loss and CO2 uptake by regulating the aperture of the stomatal pores within the leaf epidermis. Stomata aperture is regulated by the two guard cells forming the pore and changing their size in response to ion uptake and release. While our knowledge about potassium and chloride fluxes across the plasma membrane of guard cells is advanced, little is known about fluxes across the vacuolar membrane. Here we present the molecular identification of the long-sought-after vacuolar chloride channel. AtALMT9 is a chloride channel activated by physiological concentrations of cytosolic malate. Single-channel measurements demonstrate that this activation is due to a malate-dependent increase in the channel open probability. Arabidopsis thaliana atalmt9 knockout mutants exhibited impaired stomatal opening and wilt more slowly than the wild type. Our findings show that AtALMT9 is a vacuolar chloride channel having a major role in controlling stomata aperture. Aluminium-activated malate transporters are exclusive to plants, regulating the transport of ions across the membranes on which they are expressed. De Angeli and colleagues show that AtALMT9 acts as a vacuolar chloride channel that is activated by cytosolic malate, and that this regulates stomata aperture.
Collapse
|
142
|
Klemens PA, Patzke K, Deitmer J, Spinner L, Le Hir R, Bellini C, Bedu M, Chardon F, Krapp A, Neuhaus HE. Overexpression of the vacuolar sugar carrier AtSWEET16 modifies germination, growth, and stress tolerance in Arabidopsis. PLANT PHYSIOLOGY 2013; 163:1338-52. [PMID: 24028846 PMCID: PMC3813654 DOI: 10.1104/pp.113.224972] [Citation(s) in RCA: 174] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 09/11/2013] [Indexed: 05/18/2023]
Abstract
Here, we report that SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTER (SWEET16) from Arabidopsis (Arabidopsis thaliana) is a vacuole-located carrier, transporting glucose (Glc), fructose (Fru), and sucrose (Suc) after heterologous expression in Xenopus laevis oocytes. The SWEET16 gene, similar to the homologs gene SWEET17, is mainly expressed in vascular parenchyma cells. Application of Glc, Fru, or Suc, as well as cold, osmotic stress, or low nitrogen, provoke the down-regulation of SWEET16 messenger RNA accumulation. SWEET16 overexpressors (35SPro:SWEET16) showed a number of peculiarities related to differences in sugar accumulation, such as less Glc, Fru, and Suc at the end of the night. Under cold stress, 35SPro:SWEET16 plants are unable to accumulate Fru, while under nitrogen starvation, both Glc and Fru, but not Suc, were less abundant. These changes of individual sugars indicate that the consequences of an increased SWEET16 activity are dependent upon the type of external stimulus. Remarkably, 35SPro:SWEET16 lines showed improved germination and increased freezing tolerance. The latter observation, in combination with the modified sugar levels, points to a superior function of Glc and Suc for frost tolerance. 35SPro:SWEET16 plants exhibited increased growth efficiency when cultivated on soil and showed improved nitrogen use efficiency when nitrate was sufficiently available, while under conditions of limiting nitrogen, wild-type biomasses were higher than those of 35SPro:SWEET16 plants. Our results identify SWEET16 as a vacuolar sugar facilitator, demonstrate the substantial impact of SWEET16 overexpression on various critical plant traits, and imply that SWEET16 activity must be tightly regulated to allow optimal Arabidopsis development under nonfavorable conditions.
Collapse
|
143
|
Schönknecht G. Calcium Signals from the Vacuole. PLANTS (BASEL, SWITZERLAND) 2013; 2:589-614. [PMID: 27137394 PMCID: PMC4844392 DOI: 10.3390/plants2040589] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 09/21/2013] [Accepted: 09/26/2013] [Indexed: 01/13/2023]
Abstract
The vacuole is by far the largest intracellular Ca(2+) store in most plant cells. Here, the current knowledge about the molecular mechanisms of vacuolar Ca(2+) release and Ca(2+) uptake is summarized, and how different vacuolar Ca(2+) channels and Ca(2+) pumps may contribute to Ca(2+) signaling in plant cells is discussed. To provide a phylogenetic perspective, the distribution of potential vacuolar Ca(2+) transporters is compared for different clades of photosynthetic eukaryotes. There are several candidates for vacuolar Ca(2+) channels that could elicit cytosolic [Ca(2+)] transients. Typical second messengers, such as InsP₃ and cADPR, seem to trigger vacuolar Ca(2+) release, but the molecular mechanism of this Ca(2+) release still awaits elucidation. Some vacuolar Ca(2+) channels have been identified on a molecular level, the voltage-dependent SV/TPC1 channel, and recently two cyclic-nucleotide-gated cation channels. However, their function in Ca(2+) signaling still has to be demonstrated. Ca(2+) pumps in addition to establishing long-term Ca(2+) homeostasis can shape cytosolic [Ca(2+)] transients by limiting their amplitude and duration, and may thus affect Ca(2+) signaling.
Collapse
Affiliation(s)
- Gerald Schönknecht
- Department of Botany, Oklahoma State University, Stillwater, OK 74078, USA.
| |
Collapse
|
144
|
Zhang J, Baetz U, Krügel U, Martinoia E, De Angeli A. Identification of a probable pore-forming domain in the multimeric vacuolar anion channel AtALMT9. PLANT PHYSIOLOGY 2013; 163:830-43. [PMID: 23918900 PMCID: PMC3793061 DOI: 10.1104/pp.113.219832] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 08/05/2013] [Indexed: 05/18/2023]
Abstract
Aluminum-activated malate transporters (ALMTs) form an important family of anion channels involved in fundamental physiological processes in plants. Because of their importance, the role of ALMTs in plant physiology is studied extensively. In contrast, the structural basis of their functional properties is largely unknown. This lack of information limits the understanding of the functional and physiological differences between ALMTs and their impact on anion transport in plants. This study aimed at investigating the structural organization of the transmembrane domain of the Arabidopsis (Arabidopsis thaliana) vacuolar channel AtALMT9. For that purpose, we performed a large-scale mutagenesis analysis and found two residues that form a salt bridge between the first and second putative transmembrane α-helices (TMα1 and TMα2). Furthermore, using a combination of pharmacological and mutagenesis approaches, we identified citrate as an "open channel blocker" of AtALMT9 and used this tool to examine the inhibition sensitivity of different point mutants of highly conserved amino acid residues. By this means, we found a stretch within the cytosolic moiety of the TMα5 that is a probable pore-forming domain. Moreover, using a citrate-insensitive AtALMT9 mutant and biochemical approaches, we could demonstrate that AtALMT9 forms a multimeric complex that is supposedly composed of four subunits. In summary, our data provide, to our knowledge, the first evidence about the structural organization of an ion channel of the ALMT family. We suggest that AtALMT9 is a tetramer and that the TMα5 domains of the subunits contribute to form the pore of this anion channel.
Collapse
Affiliation(s)
| | | | - Undine Krügel
- Institute of Plant Biology, University of Zürich, CH–8008 Zurich, Switzerland
| | - Enrico Martinoia
- Institute of Plant Biology, University of Zürich, CH–8008 Zurich, Switzerland
| | - Alexis De Angeli
- Institute of Plant Biology, University of Zürich, CH–8008 Zurich, Switzerland
| |
Collapse
|
145
|
Yoshida K, Ohnishi M, Fukao Y, Okazaki Y, Fujiwara M, Song C, Nakanishi Y, Saito K, Shimmen T, Suzaki T, Hayashi F, Fukaki H, Maeshima M, Mimura T. Studies on vacuolar membrane microdomains isolated from Arabidopsis suspension-cultured cells: local distribution of vacuolar membrane proteins. PLANT & CELL PHYSIOLOGY 2013; 54:1571-84. [PMID: 23903016 DOI: 10.1093/pcp/pct107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The local distribution of both the vacuolar-type proton ATPase (V-ATPase) and the vacuolar-type proton pyrophosphatase (V-PPase), the main vacuolar proton pumps, was investigated in intact vacuoles isolated from Arabidopsis suspension-cultured cells. Fluorescent immunostaining showed that V-PPase was distributed evenly on the vacuolar membrane (VM), but V-ATPase localized to specific regions of the VM. We hypothesize that there may be membrane microdomains on the VM. To confirm this hypothesis, we prepared detergent-resistant membranes (DRMs) from the VM in accordance with well established conventional methods. Analyses of fatty acid composition suggested that DRMs had more saturated fatty acids compared with the whole VM in phosphatidylcholine and phosphatidylethanolamine. In the proteomic analyses of both DRMs and detergent-soluble mebranes (DSMs), we confirmed the different local distributions of V-ATPase and V-PPase. The observations of DRMs with an electron microscope supported the existence of different areas on the VM. Moreover, it was observed using total internal reflection fluorescent microscopy (TIRFM) that proton pumps were frequently immobilized at specific sites on the VM. In the proteomic analyses, we also found that many other vacuolar membrane proteins are distributed differently in DRMs and DSMs. Based on the results of this study, we discuss the possibility that VM microdomains might contribute to vacuolar dynamics.
Collapse
Affiliation(s)
- Katsuhisa Yoshida
- Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501 Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
146
|
Leitenmaier B, Küpper H. Compartmentation and complexation of metals in hyperaccumulator plants. FRONTIERS IN PLANT SCIENCE 2013; 4:374. [PMID: 24065978 PMCID: PMC3778397 DOI: 10.3389/fpls.2013.00374] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 09/03/2013] [Indexed: 05/18/2023]
Abstract
Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their "strange" behavior in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defense against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of complexation and compartmentation, different from non-hyperaccumulator plants and also non-hyperaccumulated metals. For example, in contrast to non-hyperaccumulators, in hyperaccumulators even the classical phytochelatin-inducing metal, cadmium, is predominantly not bound by such sulfur ligands, but only by weak oxygen ligands. This applies to all hyperaccumulated metals investigated so far, as well as hyperaccumulation of the metalloid arsenic. Stronger ligands, as they have been shown to complex metals in non-hyperaccumulators, are in hyperaccumulators used for transient binding during transport to the storage sites (e.g., nicotianamine) and possibly for export of Cu in Cd/Zn hyperaccumulators [metallothioneins (MTs)]. This confirmed that enhanced active metal transport, and not metal complexation, is the key mechanism of hyperaccumulation. Hyperaccumulators tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles, usually in large storage cells of the epidermis. This is mediated by strongly elevated expression of specific transport proteins in various tissues from metal uptake in the shoots up to the storage sites in the leaf epidermis. However, this mechanism seems to be very metal specific. Non-hyperaccumulated metals in hyperaccumulators seem to be dealt with like in non-hyperaccumulator plants, i.e., detoxified by binding to strong ligands such as MTs.
Collapse
Affiliation(s)
| | - Hendrik Küpper
- Fachbereich Biologie, Universität KonstanzKonstanz, Germany
| |
Collapse
|
147
|
Berry phenolics of grapevine under challenging environments. Int J Mol Sci 2013; 14:18711-39. [PMID: 24030720 PMCID: PMC3794804 DOI: 10.3390/ijms140918711] [Citation(s) in RCA: 254] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 07/27/2013] [Accepted: 08/15/2013] [Indexed: 11/17/2022] Open
Abstract
Plant phenolics have been for many years a theme of major scientific and applied interest. Grape berry phenolics contribute to organoleptic properties, color and protection against environmental challenges. Climate change has already caused significant warming in most grape-growing areas of the world, and the climatic conditions determine, to a large degree, the grape varieties that can be cultivated as well as wine quality. In particular, heat, drought and light/UV intensity severely affect phenolic metabolism and, thus, grape composition and development. In the variety Chardonnay, water stress increases the content of flavonols and decreases the expression of genes involved in biosynthesis of stilbene precursors. Also, polyphenolic profile is greatly dependent on genotype and environmental interactions. This review deals with the diversity and biosynthesis of phenolic compounds in the grape berry, from a general overview to a more detailed level, where the influence of environmental challenges on key phenolic metabolism pathways is approached. The full understanding of how and when specific phenolic compounds accumulate in the berry, and how the varietal grape berry metabolism responds to the environment is of utmost importance to adjust agricultural practices and thus, modify wine profile.
Collapse
|
148
|
Petrussa E, Braidot E, Zancani M, Peresson C, Bertolini A, Patui S, Vianello A. Plant flavonoids--biosynthesis, transport and involvement in stress responses. Int J Mol Sci 2013; 14:14950-73. [PMID: 23867610 PMCID: PMC3742282 DOI: 10.3390/ijms140714950] [Citation(s) in RCA: 333] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 07/11/2013] [Accepted: 07/11/2013] [Indexed: 12/13/2022] Open
Abstract
This paper aims at analysing the synthesis of flavonoids, their import and export in plant cell compartments, as well as their involvement in the response to stress, with particular reference to grapevine (Vitis vinifera L.). A multidrug and toxic compound extrusion (MATE) as well as ABC transporters have been demonstrated in the tonoplast of grape berry, where they perform a flavonoid transport. The involvement of a glutathione S-transferase (GST) gene has also been inferred. Recently, a putative flavonoid carrier, similar to mammalian bilitranslocase (BTL), has been identified in both grape berry skin and pulp. In skin the pattern of BTL expression increases from véraison to harvest, while in the pulp its expression reaches the maximum at the early ripening stage. Moreover, the presence of BTL in vascular bundles suggests its participation in long distance transport of flavonoids. In addition, the presence of a vesicular trafficking in plants responsible for flavonoid transport is discussed. Finally, the involvement of flavonoids in the response to stress is described.
Collapse
Affiliation(s)
- Elisa Petrussa
- Department of Agricultural and Environmental Sciences, Unit of Plant Biology, University of Udine, via delle Scienze 91, Udine I-33100, Italy; E-Mails: (E.P.); (E.B.); (M.Z.); (C.P.); (A.B.); (S.P.)
| | - Enrico Braidot
- Department of Agricultural and Environmental Sciences, Unit of Plant Biology, University of Udine, via delle Scienze 91, Udine I-33100, Italy; E-Mails: (E.P.); (E.B.); (M.Z.); (C.P.); (A.B.); (S.P.)
| | - Marco Zancani
- Department of Agricultural and Environmental Sciences, Unit of Plant Biology, University of Udine, via delle Scienze 91, Udine I-33100, Italy; E-Mails: (E.P.); (E.B.); (M.Z.); (C.P.); (A.B.); (S.P.)
| | - Carlo Peresson
- Department of Agricultural and Environmental Sciences, Unit of Plant Biology, University of Udine, via delle Scienze 91, Udine I-33100, Italy; E-Mails: (E.P.); (E.B.); (M.Z.); (C.P.); (A.B.); (S.P.)
| | - Alberto Bertolini
- Department of Agricultural and Environmental Sciences, Unit of Plant Biology, University of Udine, via delle Scienze 91, Udine I-33100, Italy; E-Mails: (E.P.); (E.B.); (M.Z.); (C.P.); (A.B.); (S.P.)
| | - Sonia Patui
- Department of Agricultural and Environmental Sciences, Unit of Plant Biology, University of Udine, via delle Scienze 91, Udine I-33100, Italy; E-Mails: (E.P.); (E.B.); (M.Z.); (C.P.); (A.B.); (S.P.)
| | - Angelo Vianello
- Department of Agricultural and Environmental Sciences, Unit of Plant Biology, University of Udine, via delle Scienze 91, Udine I-33100, Italy; E-Mails: (E.P.); (E.B.); (M.Z.); (C.P.); (A.B.); (S.P.)
| |
Collapse
|
149
|
Nunes-Nesi A, Araújo WL, Obata T, Fernie AR. Regulation of the mitochondrial tricarboxylic acid cycle. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:335-43. [PMID: 23462640 DOI: 10.1016/j.pbi.2013.01.004] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 01/24/2013] [Accepted: 01/26/2013] [Indexed: 05/04/2023]
Abstract
Recent years have seen considerable advances in our understanding of the particular physiological roles of the constituent enzymes of the tricarboxylic acid (TCA) cycle. Despite acquiring a fairly comprehensive overview of the functional importance of these proteins relatively little is known concerning how this important pathway is regulated. In this review we concentrate on the mitochondrial reactions since this organelle is the only one in which a full cycle can, at least theoretically, operate. We summarize what is known about the regulation of the enzymes of the pathway both from historical kinetic studies as well as discussing more recent transcriptional and proteomic studies and our enhanced understanding of subcellular compartmentation within the context of metabolic regulation.
Collapse
Affiliation(s)
- Adriano Nunes-Nesi
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-000 Viçosa, Minas Gerais, Brazil
| | | | | | | |
Collapse
|
150
|
Seidel T, Siek M, Marg B, Dietz KJ. Energization of vacuolar transport in plant cells and its significance under stress. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 304:57-131. [PMID: 23809435 DOI: 10.1016/b978-0-12-407696-9.00002-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The plant vacuole is of prime importance in buffering environmental perturbations and in coping with abiotic stress caused by, for example, drought, salinity, cold, or UV. The large volume, the efficient integration in anterograde and retrograde vesicular trafficking, and the dynamic equipment with tonoplast transporters enable the vacuole to fulfill indispensible functions in cell biology, for example, transient and permanent storage, detoxification, recycling, pH and redox homeostasis, cell expansion, biotic defence, and cell death. This review first focuses on endomembrane dynamics and then summarizes the functions, assembly, and regulation of secretory and vacuolar proton pumps: (i) the vacuolar H(+)-ATPase (V-ATPase) which represents a multimeric complex of approximately 800 kDa, (ii) the vacuolar H(+)-pyrophosphatase, and (iii) the plasma membrane H(+)-ATPase. These primary proton pumps regulate the cytosolic pH and provide the driving force for secondary active transport. Carriers and ion channels modulate the proton motif force and catalyze uptake and vacuolar compartmentation of solutes and deposition of xenobiotics or secondary compounds such as flavonoids. ABC-type transporters directly energized by MgATP complement the transport portfolio that realizes the multiple functions in stress tolerance of plants.
Collapse
Affiliation(s)
- Thorsten Seidel
- Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Bielefeld, Germany.
| | | | | | | |
Collapse
|