Plant Solute Transport

Plant Solute Transport......Page 1
Contents......Page 5
Preface......Page 15
Contributors......Page 19
1.1 Introduction......Page 21
1.2 Synopsis......Page 23
Reference......Page 34
2.2.1 Obtaining material for analysis......Page 35
2.2.3 Mass spectrometry......Page 36
2.3 Solute concentrations......Page 37
2.4 Organic compounds......Page 38
2.6.1 Stereological analysis......Page 39
2.6.2 Inorganic elements and electron microscopy......Page 40
2.6.3 Ion-specific microelectrodes......Page 41
2.6.5 Use of fluorescent dyes......Page 42
2.6.6 Flux analysis......Page 43
2.7.1 Vacuoles......Page 45
2.7.4 Conclusions......Page 46
References......Page 47
3.2 Water......Page 49
3.3.1 Free energy and chemical potential......Page 51
3.3.2 Water potential and water potential gradients......Page 52
3.3.3 Osmosis and colligative properties......Page 53
3.4 Cell water relations......Page 54
3.5 Water movement......Page 55
3.5.1 Water movement through the soil......Page 58
3.5.3 Water movement across a root (or leaf)......Page 59
3.6 Solute movement......Page 60
3.6.2 Diffusion – Fick’s first law......Page 61
3.6.3 Diffusion potential......Page 62
3.6.5 Donnan systems......Page 63
3.7 Coupling of water and solute fluxes......Page 64
References......Page 65
4.2.1 Plant membrane composition......Page 67
4.2.2 Plant membrane structure......Page 70
4.3 Studying solute transport across plant membranes......Page 71
4.4.1.1 Solution design......Page 72
4.4.2 Accumulation and net uptake......Page 73
4.4.3 Radioactive tracers......Page 74
4.4.4 Fluorescent solute probes......Page 75
4.4.5 Electrophysiology......Page 77
4.4.5.1 Voltage-based measurements (membrane potential and ion concentration)......Page 78
4.5.1 Isolating membranes......Page 80
4.5.2 Assaying transport activities of protoplasts and membrane vesicles......Page 81
4.6.1 Revealing the molecular identity of transporters and testing gene function......Page 83
4.6.2 Location of transport proteins......Page 84
4.6.3 Heterologous expression......Page 85
4.8 Future development......Page 86
References......Page 87
5.1 Introduction......Page 95
5.1.2 Definitions and terminology......Page 96
5.1.3 Some formalisms......Page 99
5.2.1 Diffusion through membranes......Page 101
5.2.2 Facilitated diffusion through carriers......Page 102
5.2.3 Transport through ion channels......Page 103
5.2.3.1 Potassium channels......Page 104
5.2.4 Transport through water channels......Page 105
5.3.1 Primary proton pumps......Page 107
5.3.1.1 P-type ATPases......Page 108
5.3.1.2 V-type ATPases......Page 109
5.3.2.1 P-type Ca2+ pumps......Page 110
5.3.2.2 Heavy metal ATPases......Page 111
5.4 Secondary active transport......Page 112
5.4.1 Potassium uptake......Page 113
5.4.2 Nitrate transport......Page 114
5.4.4 Non H+ -coupled secondary transport......Page 115
References......Page 116
6.2.1 Change of cell volume......Page 119
6.2.2 Nutrient acquisition......Page 122
6.2.3 Stress responses......Page 126
6.3 Molecular mechanism of regulation......Page 127
6.3.1 Transcriptional regulation......Page 128
6.3.2.1 Autoinhibition......Page 129
6.3.2.2 14-3-3 proteins......Page 131
6.3.2.3 Calmodulin......Page 133
6.3.2.4 Cyclic nucleotides......Page 134
6.3.2.5 Heteromerisation......Page 136
6.4 Traffic of ion transporters......Page 137
References......Page 140
7.1.1 Research to identify solute transport proteins in plant organelles......Page 153
7.1.1.1 Benefits of a model plant: Arabidopsis thaliana......Page 154
7.2 Chloroplasts......Page 156
7.2.2 Transport across the outer envelope: general diffusion or regulated channels?......Page 157
7.2.2.1 A porin in the outer envelope of plastids?......Page 158
7.2.3.2 Major-facilitator-mediated transport......Page 164
7.2.3.3 Carriers in the inner envelope of plastids......Page 166
7.2.3.1 The phosphate translocator family......Page 162
7.2.4.1 ABC transporters......Page 167
7.2.4.2 Ion transport......Page 169
7.2.4.3 Transport of metal ions......Page 170
7.3.1 The function of plant mitochondria......Page 173
7.3.2 Transport across the outer membrane: the porin VDAC......Page 174
7.3.3.1 Transporters involved in ATP production......Page 176
7.3.3.2 Carriers for transport of TCA cycle intermediates......Page 178
7.3.3.3 Amino acid transport across mitochondrial membranes......Page 179
7.3.4.1 ABC transporters......Page 180
7.3.4.2 Ion channels......Page 181
7.4 Peroxisomes......Page 182
7.4.2.1 A porin in the peroxisomal membrane......Page 183
7.4.2.2 Specific transport proteins in the peroxisomal membrane......Page 185
7.5 Photorespiration: transport between plastids, mitochondria and peroxisomes......Page 186
7.6 Vacuoles......Page 188
7.6.1 Generating a pH gradient across the tonoplast: H+ -ATPase and H+ -pyrophosphatase......Page 189
7.6.2.1 Malate......Page 190
7.6.3.1 Aquaporins in the vacuole are tonoplast-intrinsic proteins......Page 191
7.6.3.2 ABC transporters in the tonoplast......Page 192
7.6.4.1 Ion channels......Page 193
7.6.4.2 Calcium, sodium and magnesium uptake involves active transport......Page 195
7.6.4.3 Transport of transition metals......Page 197
References......Page 198
8.2 Soil composition......Page 213
8.3 Root exploration of the soil......Page 214
8.4 Physical factors affecting root uptake: depletion zones and Donnan potentials......Page 216
8.5.1 The role of apoplastic barriers......Page 217
8.5.2 Root hairs and cortical cells......Page 218
8.6 Solute uptake from different root zones......Page 221
8.7 Transport of solutes to the xylem......Page 223
8.8.1 Radioisotopic studies......Page 224
8.8.3 Kinetics of uptake in response to solute availability......Page 227
References......Page 229
9.2.1 Xylem structure......Page 234
9.2.2 Physics of water flow and evolutionary aspects of conduit development......Page 236
9.2.3 Water flow between xylem elements: safety mechanisms......Page 237
9.2.4 Hydraulics of the sap lift: general overview......Page 239
9.2.5 Driving force for water movement in the xylem......Page 241
9.2.6 Controversies and additional mechanisms......Page 242
9.3.1 General features of xylem ion loading......Page 244
9.3.2.1 Potassium......Page 245
9.3.2.2 Sodium......Page 246
9.3.2.4 Gating factors......Page 247
9.3.3 Xylem-sap composition......Page 248
9.3.4 Factors affecting ion concentration in the xylem......Page 249
9.3.5 Xylem unloading in leaves......Page 250
References......Page 251
10.1 Introduction......Page 255
10.2.1.1 Sieve tubes are anucleate......Page 256
10.2.1.2 Sieve plate blockage......Page 257
10.2.2.2 Plasmodesmatal selectivity......Page 258
10.3.1.2 Other carbohydrates......Page 260
10.3.2.1 Variation in sieve element composition......Page 261
10.3.3 Nitrogen......Page 262
10.3.4 mRNA......Page 263
10.3.4.2 Structural genes and cell-wall enzymes......Page 264
10.3.4.7 Transport......Page 265
10.3.5.1 Oxidative stress......Page 266
10.3.5.4 Metabolism......Page 267
10.4 Sieve element water relations......Page 268
10.4.1.2 Sieve element turgor pressure......Page 269
10.4.2 Flow in the phloem......Page 270
10.4.3.1 Symplastic or apoplastic loading?......Page 271
10.4.3.2 Transporters facilitating apoplastic loading......Page 274
10.4.3.3 H+/ATPase......Page 275
10.4.4.1 Evidence for unloading pathway: root tips......Page 277
10.4.4.3 Evidence for unloading pathway: seed coats......Page 279
10.4.5 Resource partitioning through the phloem......Page 280
10.5.2 Sap-feeding insects......Page 281
10.6 Conclusions......Page 282
References......Page 283
11.1 Introduction......Page 295
11.2.2 Bioavailability of the element......Page 296
11.2.3 Movement of nutrients towards roots......Page 298
11.2.5 Losses......Page 299
11.3.1 Affinity and capacity of transport processes in the roots......Page 300
11.3.2 Exploration and exploitation of soil volume by roots......Page 302
11.4 Acquisition of phosphorus......Page 304
11.5 Protected cropping systems: hydroponics as an example of ‘ideally’ controlled conditions......Page 306
References......Page 307
12.1 Introduction......Page 310
12.1.1 Terminology......Page 311
12.2 Deficiency and efficiency: iron in alkaline soils......Page 313
12.2.1 ‘Strategy I’: reduction-dependent iron uptake......Page 315
12.2.2 ‘Strategy II’: phytosiderophores......Page 316
12.3.1 Cluster roots and root exudates......Page 319
12.3.2 Mycorrhizal symbiosis......Page 320
12.4 Toxicity and tolerance–aluminium in acid soils......Page 321
12.5 Toxicity and tolerance–essential and non-essential metals......Page 323
12.5.1 Hyperaccumulation......Page 324
12.5.2 Ion transport in hyperaccumulators......Page 325
12.5.3 Phytochelatins......Page 326
12.6 Concluding remarks......Page 328
References......Page 329
13.1 Introduction......Page 334
13.2 Plant responses to reduced water availability......Page 335
13.3.1 Stomatal regulation......Page 338
13.3.2 Leaf area regulation......Page 340
13.3.3 Consequences: interaction with leaf temperature......Page 341
13.4.1 Water potential of drying soil......Page 342
13.4.2 Osmotic adjustment......Page 343
13.4.3 Compatible solutes/osmolytes/osmoprotectants......Page 344
13.5.1 Constitutive formation of deep roots......Page 346
13.5.3 Root conductance......Page 347
13.6 Mechanisms to increase water-use efficiency: C4 and crassulacean acid metabolism (CAM)......Page 348
13.6.1 C4 photosynthesis......Page 349
13.6.2 CAM......Page 351
13.7 Gene regulation......Page 354
References......Page 355
14.1 Introduction......Page 360
14.2 External concentration of salt up to about 50 mM NaCl......Page 361
14.3 External concentration of salt up to about 100–150 mM NaCl......Page 363
14.4 External concentration of salt above about 150–200 mM......Page 364
14.5 ‘Molecular’ tolerance......Page 365
14.6 Cellular tolerance......Page 366
14.8 Salt glands......Page 367
14.9 Selectivity at the root......Page 368
14.10 Transport from root to shoot......Page 373
14.11 Transport from shoot to root......Page 376
14.12 Leaf cells......Page 377
14.13 Prospects......Page 381
14.14 Concluding remarks......Page 384
References......Page 385
15.1 Introduction......Page 391
15.3 Desiccation tolerance in seeds......Page 392
15.3.2 Intracellular de-differentiation......Page 394
15.3.4 Antioxidant systems......Page 395
15.3.5 Protective molecules......Page 396
15.3.6 Amphiphilic molecules......Page 398
15.4 Vegetative tissues......Page 399
15.4.2 Physical characteristics......Page 402
15.4.4 Low-molecular-weight carbohydrates......Page 403
15.4.6 Signals......Page 405
15.4.7 Constraints to the development of desiccation tolerance......Page 406
References......Page 408
Index......Page 411
Colour plate......Page 427