Introduction to Plant Pathology

Introduction to Plant Pathology......Page 3
Contents......Page 9
Preface......Page 17
1.1 Introduction......Page 19
1.3.1 Parasitic angiosperms......Page 20
1.3.2 Fungi......Page 22
1.3.3 Nematodes......Page 30
1.3.4 Algae......Page 32
1.3.5 Oomycetes......Page 33
1.3.7 Trypanosomatids......Page 34
1.3.8 Bacteria......Page 35
1.3.9 Phytoplasmas......Page 46
1.3.10 Viruses......Page 47
1.3.11 Viroids......Page 48
2.1 Introduction......Page 51
2.2 Host range and symptomatology......Page 53
2.3 Morphology of the causal organism......Page 56
2.4 Selective media......Page 57
2.5 Biochemical markers......Page 58
2.5.1 Substrate metabolism......Page 59
2.5.3 Protein analysis......Page 60
2.5.4 Serological techniques......Page 61
2.5.5 Nucleic acid techniques......Page 64
2.5.6 Choice of diagnostic techniques......Page 75
2.5.7 Ralstonia solanacearum – a case study......Page 76
3.1 Introduction......Page 79
3.2 Theories of epidemic development......Page 80
3.2.1 Development of disease in time......Page 81
3.2.2 Development of disease in space......Page 84
3.2.3 Fitting disease progress curves to epidemiological data......Page 87
3.3.1 Sources of inoculum......Page 88
3.3.2 Vectors......Page 93
3.4.1 Host-plant distribution......Page 98
3.5 The role of the environment......Page 99
3.5.1 The soil......Page 100
3.5.2 The atmosphere......Page 102
Summary......Page 107
4.1 Introduction......Page 108
4.2.1 Measurement of disease pressure in the soil......Page 109
4.2.2 Measurement of pathogen populations in the soil......Page 110
4.2.3 Measurement of pathogen populations in the air......Page 113
4.2.4 Measurement of pathogens in the plant......Page 114
4.3 Measurement of symptoms......Page 116
4.5 Establishing the relation between disease and yield......Page 120
4.5.1 Critical-point models......Page 121
4.5.2 Multiple-point models and area under the disease progress curve......Page 122
4.5.3 Coupling disease progress curves with plant growth......Page 123
4.5.4 Coupling disease predictions with economic loss......Page 124
5.1 Introduction......Page 125
5.2.1 Eradicating pathogens from seed and propagative material......Page 127
5.2.2 Eradicating sources of inoculum by rouging and pruning......Page 128
5.2.4 Eradicating inoculum from the soil......Page 132
5.2.5 Control of soil-borne plant disease through the addition of minerals and amendments and the alteration of pH......Page 133
5.3 Reducing inoculum multiplication......Page 136
5.4 Reducing the effectivenes of inoculum......Page 137
5.4.2 Biological control......Page 139
5.5.1 Screening for biological control agents......Page 151
5.5.2 The development of biological control agents......Page 153
5.5.3 The application and establishment of biological control agents......Page 155
5.6.1 Controlling the spread of wind-borne inoculum......Page 156
5.6.2 Controlling the spread of water-borne inoculum......Page 158
5.6.3 Controlling the spread of soil-borne inoculum......Page 159
5.6.4 Controlling the spread of inoculum in infected propagative material: the role of quarantine......Page 161
5.6.5 Controlling the spread of inoculum by vectors......Page 162
Summary......Page 165
6.1 Introduction......Page 166
6.2 The physical and chemical characteristics of materials that cover plants......Page 167
6.3 The physical and chemical characteristics of plant cell walls......Page 168
6.4 Chemotaxis, encystment and chemotropism......Page 171
6.5 Passive entry through natural openings......Page 175
6.6.1 Hydrophobicity......Page 176
6.6.3 Chemical signals......Page 177
6.6.4 Topographical features......Page 181
6.7 Adhesion......Page 182
6.8 Breaching the cell wall by mechanical force......Page 183
6.9 Breaching the cell wall by the production of degradative enzymes......Page 185
6.9.1 Enzymes that degrade the surface layers of plants: waxes, cutin and suberin......Page 186
6.9.2 Pectolytic enzymes......Page 188
6.9.3 Cellulases and xylanases......Page 193
6.9.5 Proteases......Page 194
6.10 Global regulation of degradative enzymes......Page 195
6.11 Nutrition of the pathogen......Page 196
6.12 Movement of viruses through the plant......Page 197
Summary......Page 199
7.1 Introduction......Page 200
7.2.1 Auxins......Page 201
7.2.2 Cytokinins......Page 204
7.2.3 Gibberellins......Page 205
7.2.4 Ethylene......Page 206
7.2.5 Abscisic acid (ABA)......Page 208
7.2.6 Jasmonates......Page 210
7.2.7 Brassinosteroids......Page 211
7.3.1 Abnormal growth......Page 212
7.3.3 Stunting......Page 215
7.3.4 Chlorosis and necrosis......Page 216
7.3.6 Abscission......Page 217
7.4 Crown gall......Page 218
8.1 Introduction......Page 223
8.2 Macroscopic symptoms......Page 224
8.3 Bioassay......Page 226
8.4.1 Host-selective toxins from Alternaria species......Page 228
8.4.2 Host-selective toxins from Helminthosporium species and Mycosphaerella zeaemaydis......Page 232
8.4.3 Host-selective toxins from other species......Page 239
8.5 Non-host-selective toxins (NSTs)......Page 241
8.5.1 NSTs from bacteria......Page 242
8.5.2 NSTs from Oomycetes......Page 248
8.5.3 NSTs from fungi......Page 249
8.6 Control of toxin biosynthesis......Page 256
9.1 Introduction......Page 259
9.2 Physical barriers......Page 260
9.3.1 Low molecular weight compounds......Page 261
9.3.2 High molecular weight compounds......Page 272
Summary......Page 279
10.1 Introduction......Page 280
10.2 Pioneering experiments......Page 281
10.3 Some experiments which led to the formulation of the gene-for-gene concept......Page 283
10.4 Variations on the gene-for-gene concept......Page 286
10.5 Molecular corroboration of the gene-for-gene concept......Page 288
10.5.1 Cloning, structure and expression of avirulence genes......Page 289
10.5.2 Function and organization of avirulence genes......Page 294
10.5.3 Cloning, structure and expression of resistance genes......Page 295
10.5.4 Function and organization of resistance genes......Page 301
10.6.1 The evolution of avirulence genes......Page 304
10.6.2 The evolution of resistance genes......Page 306
10.7 Hrp genes......Page 308
Summary......Page 311
11.1 Introduction......Page 312
11.2.1 The oxidative burst......Page 313
11.2.3 Cross-linking of cell-wall proteins......Page 315
11.2.4 Callose synthesis and deposition......Page 316
11.3.1 The hypersensitive response......Page 317
11.3.2 Phytoalexins......Page 318
11.3.3 Lignification......Page 329
11.3.4 Suberization......Page 331
11.3.5 Synthesis of hydroxyproline-rich glycoproteins (HRGPs)......Page 332
11.3.6 Pathogenesis-related proteins (PRPs)......Page 333
11.3.7 Systemic acquired resistance (SAR)......Page 335
11.3.8 Induced systemic resistance (ISR)......Page 336
11.4.1 Abiotic elicitors......Page 337
11.4.2 Biotic elicitors......Page 338
11.5 Elicitor perception......Page 341
11.6 Signalling......Page 342
11.6.1 Increases in cytosolic calcium......Page 343
11.6.2 Mitogen-activated protein kinases (MAP kinases)......Page 344
11.6.3 Salicylic acid (SA)......Page 345
11.6.4 Jasmonates......Page 346
11.6.6 Integration of signalling pathways......Page 347
11.7 Overcoming induced resistance......Page 349
12.1 Introduction......Page 351
12.2.1 Exploiting chemo-attractants, repellents and immobilizers......Page 352
12.2.2 Exploiting chemical signals that influence germination and growth of pathogen propagules......Page 354
12.2.4 Exploiting physical cues and barriers to penetration......Page 356
12.3.2 Tolerance of toxins......Page 358
12.3.3 Identification of plants genes that recognize essential virulence components of pathogens......Page 360
12.4.1 Exploiting phytoanticipins......Page 361
12.4.2 Exploiting phytoalexins......Page 362
12.4.3 Exploiting acquired resistance......Page 363
12.5 Genetic approaches to the control of disease......Page 365
12.6 Plant transformation......Page 368
12.7.1 Transformation with genes encoding proteins that inhibit pathogen enzymes......Page 370
12.7.3 Enhancing concentrations of saponins......Page 371
12.7.4 Transformation with genes encoding antimicrobial peptides......Page 372
12.7.6 Modifying the phytoalexin response......Page 374
12.7.8 Pathogen-derived resistance......Page 375
12.7.9 Transformation with resistance genes......Page 379
Epilogue......Page 383
Glossary......Page 385
References......Page 393
Index......Page 457