Physiological Plant Pathology

1. General.- 1.1 History of Physiological Plant Pathology.- 1.2 Some Aspects of Host-Pathogen Interactions.- 1. Introduction.- 2. The Response of the Host.- 2.1 Resistance.- 2.2 Susceptibility.- 2.3 Economic Damage and Tolerance to Disease.- 2.4 Symptom Expression and Spurious Effects.- 3. Pathogenicity and Virulence.- 4. The Influence of Disease in the Design of Experimental Procedures.- 5. The Control of Host-Pathogen Interactions.- 5.1 Genetic Control.- 5.2 Flor’s Gene-for-gene Hypothesis.- 5.3 Metabolic Control.- 5.4 Modes of Inheritance and Induced Resistance versus Induced Susceptibility.- 5.5 Recognition Phenomena in Specificity.- 5.6 The Influence of Environment.- 6. Special Topics.- 6.1 Quantitative Measures of Disease and of Pathogens.- 6.2 Genetic Control of Experimental Material.- 6.3 Model Systems.- 6.4 Challenge Inoculations.- References.- 2. Spore Germination and Its Regulation.- 2.1 Control of Spore Germination and Infection Structure Formation in the Fungi.- 1. Introduction.- 2. Self-Inhibition and Stimulation of Germination.- 2.1 Germination Inhibitors from the Parent Colony.- 2.2 Germination Inhibitors in Spores.- 2.3 Self-Stimulation of Germination.- 3. Inhibitors and Stimulants of Germination in Soil.- 3.1 Soil Fungistasis.- 3.2 Stimulants in Soil.- 4. Stimulants and Inhibitors of Germination at Plant Surfaces.- 4.1 Inhibitors.- 4.2 Stimulants.- 5. Formation of Infection Structures.- 5.1 Genetic Basis of Infection Structure Formation.- 5.2 Experimental Studies on Infection Structure Formation.- 6. Conclusions.- References.- 2.2 Protein and Nucleic Acid Metabolism during Germination.- 1. Introduction.- 2. Facultative Parasites.- 2.1 Germination of Conidia.- 2.2 Germination of Zoospores.- 2.3 Germination of Basidiospores.- 3. Obligate Parasites.- 3.1 Introduction.- 3.2 Changes in Proteins and Nucleic Acids during Germination.- 3.3 Changes in Ribosome Activity during Spore Germination.- 3.4 Differentiation.- 3.5 Conclusions.- References.- 2.3 The Effect of Roots on the Activity of Soil-borne Plant Pathogens.- 1. Introduction.- 2. The Pathogen in the Soil.- 3. The Root-Soil Interface.- 3.1 The Rhizosphere.- 3.2 The Rhizoplane.- 4. The Mechanism of the Root Effect.- 4.1 Root Tissue Debris.- 4.2 Root Exudates.- 4.3 Oxygen and Carbon Dioxide.- 4.4 Volatile Emanations from Roots.- 4.5 Root Surface Effects.- 5. Methods of Studying Response of Pathogens to Roots.- 6. Behavior of Specific Pathogens.- 7. Discussion.- References.- 3. Cytology and Physiology of Penetration and Establishment.- 3.1 Cytology of Virus Infection and Virus Transport.- 1. Introduction.- 2. Methods of Study.- 3. Infection.- 4. Cytology of Virus Multiplication.- 5. Virus Aggregation, Anomalous Inclusions and Structural Changes in Infected Cells.- 6. Transport.- 7. Conclusions.- References.- 3.2 Plant Mycoplasma Diseases.- 1. Introduction.- 2. Historical Background.- 3. Terminology and Definitions.- 4. Methodology.- 5. Effects of MLO on Plants.- 6. Effects of MLO on Insect Vectors.- 7. Chemotherapy and Heat Therapy.- 8. Unsolved Problems.- 9. Summary and Conclusions.- References.- 3.3 Physiological and Cytological Aspects of the Bacterial Infection Process.- 1. Introduction.- 2. Pre-penetration.- 2.1 Motility, Aerotaxis and Chemotaxis.- 2.2 Predisposing Environmental Features.- 2.3 Morphological Barriers to Infection.- 3. Penetration.- 3.1 Natural Openings.- 3.2 Wounds.- 4. Growth of the Bacteria in vivo.- 4.1 Inoculum Size Required to Establish an Infection.- 4.2 The Sites of Bacterial Multiplication.- 4.3 Bacterial Proliferation in Connection with the Hypersensitive Reaction.- 4.4 Growth of Saprophytic Bacteria in Plant Tissue.- 5. Microbiological Antagonism and Commensalism.- 6. Summing-up.- References.- 3.4 Cytology of Penetration and Infection—Fungi.- 1. Introduction.- 2. The Use of Modern Methodology.- 3. Primary Penetration.- 3.1 Primary Penetration Types.- 3.2 The Mechanism(s) of Primary Penetration.- 4. Infection.- 4.1 Specialized Structures Associated with Infection.- 4.2 Effects of Infection on Susceptible Host Cytology.- 5. Relating Structure to Function.- References.- 3.5 Nematode Parasites of Plants, Their Ecology and the Process of Infection.- 1. Introduction.- 2. Physiology of Nematodes outside Their Hosts.- 3. Attraction and Penetration.- 3.1 Attraction.- 3.2 Feeding Behavior.- 3.3 Wall-degrading Enzymes.- 4. Nutrition.- 4.1 Cultures.- 4.2 Sex Determination.- 4.3 Growth Rates.- 4.4 Mineral Nutrition of Host.- 5. Cyto- and Histopathology.- 6. Biochemical Changes in Infected Tissues.- 7. Remarks on Breeding for Resistance.- References.- 4. Forces by Which the Pathogen Attacks the Host Plant.- 4.1 Host-specific Toxins in Relation to Pathogenesis and Disease Resistance.- 1. Introduction.- 2. The Agronomic Background.- 3. Development and Use of Toxin Bioassays.- 4. Genetic Studies of the Toxin Problem.- 5. Isolation and Characterization of Toxins.- 6. Comparative Effects of the Fungi and Their Toxins on Susceptible Cells and Tissues.- 7. The Resistant Cell in Relation to Toxin.- 8. Summary.- References.- 4.2 Non-specific Toxins.- 1. Introduction.- 2. Definitions.- 3. Production of Phytotoxic Compounds in vitro by Plant Pathogens.- 4. Assay Systems for Phytotoxicity.- 5. Purification of Toxins.- 6. Lowest Effective Concentration or Doses.- 7. Chemistry of Phytotoxic Compounds.- 8. Mode of Action of Phytotoxic Compounds.- 9. Toxins in Relation to Pathogenesis.- 10. Biosynthesis and Degradation of Toxins.- 11. Uses of Phytotoxic Compounds.- 12. Phytopathogens Which Produce Phytotoxic Compounds.- 13. Concluding Remarks.- References.- 4.3 Degradation of Plant Cell Walls and Membranes by Microbial Enzymes.- 1. Introduction.- 2. Structural Components.- 3. Enzymes Which Degrade Plant Structural Elements.- 3.1 Cell Wall Degradation.- 3.2 Membrane Degradation.- 4. Relationships of Enzymatic Alterations of Structural Constituents to Pathogenesis.- 4.1 Alterations of Cell Wall Constituents.- 4.2 Enzymatic Degradation of Membranes.- 5. Summary and Additional Considerations.- References.- 4.4 Morphogenic Determinants as Exemplified by the Crown-gall Disease.- 1. Introduction.- 1.1 Historical Background and Related Diseases.- 1.2 Gall Morphology and Structure.- 1.3 General Concepts.- 2. The Causal Agent.- 2.1 Taxonomic Relationships of the Agrobacteria.- 2.2 Agrobacterium Genetics.- 3. The Tumor Inception Process.- 3.1 Host Susceptibility.- 3.2 Wound Requirement.- 3.3 Site Attachment Requirement.- 3.4 Bacterial Metabolism Requirement.- 3.5 Complementation in Tumor Induction.- 3.6 Time of Initiation.- 3.7 Number of Cells Converted per Bacterium.- 3.8 The Tumor-Inducing Principle, Nucleic Acid and Phage.- 3.9 Role of Plant-growth Regulators.- 4. Tumor Development.- 5. Tumor Metabolism and the Autonomous State.- 6. Crown-gall and Cancer.- 7. Current Status and New Directions.- References.- 4.5 Sub-cellular Organization in Host-Parasite Interactions.- 1. Introduction.- 2. Methods for Studying Sub-cellular Organization in Plants.- 2.1 Histochemical and Immunohistochemical Methods.- 2.2 Cytochemical and Biochemical Methods.- 3. Alterations of Sub-cellular Organization during Disease.- 3.1 Organization of Cell Compartments.- 3.2 Examination of Changes in Host Lysosomes in Disease.- 4. Role of Extracellular Products in Disease.- 4.1 Extracellular Fungal Enzymes and the Death of Host Cells.- 5. Concluding Remarks.- References.- 5. Physiology of Host Response to Infection.- 5.1 Permeability Alterations in Diseased Plants.- 1. Introduction.- 2. Cell Permeability Theories.- 3. Pathological Changes in Permeability.- 3.1 Historical.- 3.2 Methods of Detection and Measurement of Permeability Changes in Diseased Plants.- 4. Relation of Permeability Alterations to Pathological Changes in Metabolism.- 4.1 Compatible and Incompatible Combinations.- 4.2 Transition Zones.- 4.3 Altered Permeability as an Initial Effect in Pathogenesis.- 5. Relation of Permeability Alterations to Pathological Changes in Ultrastructure.- References.- 5.2 Water Status and Imbalance.- 1. Introduction.- 2. Water Status of Plant Tissues.- 2.1 Components of Tissue Water Potential.- 2.2 Methods for Measurement of Pathogen-induced Changes in Tissue Water Potential and Its Components.- 3. Water Movement in Plants.- 3.1 Liquid Water Movement in the Plant.- 3.2 Pathogen-induced Resistances to Water Movement in Plants.- 4. Transpiration.- 4.1 Parameters Governing Transpiration Rate.- 4.2 Pathogen-induced Changes in Transpiration.- 5. Concluding Remarks.- References.- 5.3 The Carbon Balance of Diseased Plants: Changes in Respiration, Photosynthesis and Translocation.- 1. Introduction.- 2. Respiration.- 2.1 Historical.- 2.2 Uncoupling Factors in Disease.- 2.3 Changes in Respiratory Pathways during Infections.- 2.4 Terminal Oxidases and Electron Transport.- 2.5 The Significance of Respiratory Changes.- 3. Photosynthesis.- 3.1 Diseases Caused by Biotrophs.- 3.2 Virus Diseases.- 3.3 Diseases Caused by Facultative Parasites.- 4. Carbon Accumulation and Translocation.- 4.1 Mechanisms.- 4.2 Significance of Altered Transport.- References.- 5.4 Nucleic Acids in Host-Parasite Interactions.- 1. Introduction.- 2. Methodological Problems.- 3. Cytology of the Host Response as Related to Nucleic Acids.- 4. Quantitative and Qualitative Changes in Nucleic Acids in Infected Plants.- 4.1 Total RNA.- 4.2 Total DNA.- 4.3 Ribosomal RNA in Cytoplasm and Chloroplasts.- 4.4 Soluble RNA.- 4.5 Messenger RNA.- 5. Nucleic Acid Degrading Enzymes.- 6. Nucleotides and Nucleosides.- 7. Effects of Antimetabolites and Inhibitors of RNA and DNA Synthesis.- 8. Conclusions.- References.- 5.5 Protein Metabolism.- 1. Introduction.- 2. Recognition of the “Non-self” by the Host Plant.- 3. Changes in Protein Metabolism and Injury.- 4. Plant Responses to Mechanical Cutting.- 4.1 Wound Respiration.- 4.2 Enzyme Synthesis.- 4.3 Cell Organelle Formation.- 4.4 Enzyme Degradation or Inactivation.- 4.5 The Inducing Factor.- 5. Responses of Adjacent Noninfected Tissue to Infection.- 6. Protein Metabolism in Resistant or Susceptible Tissue Reactions.- 7. Changes in Protein Metabolism in Infected Tissue Containing Pathogens.- References.- 5.6 Natural Growth Regulators.- 5.6.1 Endogenous Cytokinins in Healthy and Diseased Plants.- 1. Introduction.- 2. Natural Occurrence of Cytokinins.- 3. Biological Properties of Cytokinins.- 4. Isolation, Identification and Quantitative Determination.- 4.1 Methods of Extraction and Purification.- 4.2 Bioassays.- 5. Origin, Metabolism and Transport of Cytokinins in the Plant.- 6. The Role of Cytokinins in Plant Diseases.- 6.1 Green-Island Formation.- 6.2 Fasciation Disease and False Broomrape Disorder.- 6.3 Crown Gall.- 6.4 Clubroot.- 6.5 Rust Gall Formation.- 6.6 Root Knot Galls.- 6.7 Other Disease Symptoms.- 6.8 Final Remarks.- References.- 5.6.2 Endogenous Auxins in Healthy and Diseased Plants.- 1. Introduction.- 2. Biological Properties of Auxin.- 3. Methods of Extraction and Chemical Analysis.- 4. Bioassay Methods.- 5. Changed Levels of Auxins in Plant Diseases.- 5.1 Fungus Diseases.- 5.2 Bacterial Diseases.- 5.3 Virus Diseases.- 6. The Origins of Changed Auxin Levels in Pathogenesis.- References.- 5.6.3 The Involvement of Ethylene in Plant Pathogenesis.- 1. Introduction.- 2. Natural Occurrence and Properties of C2H4.- 3. Methodology Used in the Identification of the Gas.- 3.1 Bioassays.- 3.2 Physico-chemical Methods.- 4. Ethylene Biosynthesis.- 5. The Production of Ethylene by Diseased Tissue.- 5.1 Ethylene and Enhanced Enzyme Activity.- 5.2 Ethylene and Disease Resistance.- 5.3 Ethylene as a Phytotoxin.- References.- 5.6.4 Endogenous Gibberellins in Healthy and Diseased Plants.- 1. Introduction.- 2. Chemical and Biological Properties of Gibberellins.- 3. Methods of Extraction and Chemical Identification.- 4. Gibberellin Bioassays.- 5. The Production of Gibberellins by Plant Pathogens and Other Micro-organisms.- 5.1 Fungi.- 5.2 Bacteria.- 6. The Involvement of Gibberellins in Plant Disease.- References.- 5.6.5 Endogenous Inhibitors in Healthy and Diseased Plants.- 1. Introduction.- 2. Natural Occurrence of ABA.- 3. Methods of Extraction and Chemical Analysis.- 4. Bioassay Methods.- 5. The Involvement of ABA in Plant Diseases.- 5.1 Stunting Syndromes.- 5.2 The Role of ABA in Wilting Plants.- References.- 5.7 Oxidative Enzymes.- 1. Introduction.- 2. Peroxidase and Catalase.- 2.1 Characteristics.- 2.2 Physiological Function.- 2.3 Function in the Infected Plant.- 3. Phenoloxidases.- 3.1 Characteristics.- 3.2 Physiological Function.- 3.3 Function in the Infected Plant.- 4. Cytochrome Oxidase.- 5. Ascorbic Acid Oxidase.- 6. Glycolic Acid Oxidase.- 7. Dehydrogenases.- 8. Conclusions.- References.- 5. 8 Phytoalexins.- 1. Introduction.- 2. Leguminosae.- 3. Solanaceae.- 4. Malvaceae.- 5. Convolvulaceae.- 6. Umbelliferae.- 7. Gramineae.- 8. Rosaceae.- 9. Compositae.- 10. Conclusions.- References.- 5.9 Preformed Substances as Potential Protectants.- 1. Introduction.- 2. Unsaturated Lactones.- 2.1 Occurrence and Distribution.- 2.2 Chemistry.- 2.3 Antimicrobial Activity.- 2.4 Role of Tuliposides.- 3. Cyanogenic Glycosides.- 4. Sulphur Compounds.- 4.1 Leek Oils.- 4.2 Mustard Oils.- 5. Phenols and Phenolic Glycosides.- 6. Saponins.- 6.1 Occurrence and Distribution.- 6.2 Saponin Determination.- 6.3 Chemistry and Biological Activity.- 6.4 Mode of Action.- 6.5 Role in Antifungal Resistance.- 7. Mycorrhiza.- 8. Inhibitors of Fungal Enzymes.- 9. Miscellaneous.- 10. Role of Preformed Inhibitory Substances.- References.- 5.10. Metabolic Regulation in Host-Parasite Interactions.- 1. Concepts of Metabolic Regulation and Possible Application to Host-Parasite Interactions.- 2. Assessment of Intermediary Metabolism.- 2.1 Selection of Appropriate Procedures.- 3. Compartmentation as a Regulatory Device.- 3.1 Sites of Compartmentation and Functional Roles.- 3.2 Detection of Compartmentation in vivo.- 3.3 Compartmentation in Host-Parasite Interactions.- 4. Enzymes as a Regulatory Device.- 5. Energy Charge.- 6. Pyridine Nucleotides as Regulators of Metabolism.- 7. The Pasteur Effect.- References.- 6. Modification of the Host Response—Predisposition.- 1. The Problem.- 2. Conditions Which Predispose Plants to Disease.- 2.1 Temperature.- 2.2 Humidity.- 2.3 Light.- 2.4 Chemicals.- 2.5 Tillage.- 2.6 Pruning.- 2.7 Grafting.- 2.8 Vigor.- 2.9 Prior Infection.- 2.10 Nonparasitic Diseases.- 2.11 Agronomic Practices.- 3. The Future.- References.- 7. Biotrophic Parasites in Culture.- 7.1 Growth of Biotrophic Parasites in Axenic Culture.- 1. Introduction.- 2. Culture of Rust Fungi from Uredospores.- 3. Mycelial Types Formed in Axenic Culture.- 4. Nutritional Studies.- 5. Pathogenicity of Axenic Cultures.- 6. Factors Affecting the Development of Individual Sporelings.- 7. Axenic Culture of Other Obligate Fungi.- 8. The Culture of Mycoplasma-like Organisms.- 9. Conclusions.- References.- 7.2 Growth of Biotrophic Parasites in Tissue Culture.- 1. Introduction.- 2. Plant Tissue Culture Methods.- 3. The Growth of Viruses in Tissue Culture.- 3.1 Growth in Callus Tissues.- 3.2 Production of Virus-free Plants.- 3.3 Growth in Cell Cultures.- 4. The Growth of Biotrophic Fungi in Tissue Culture.- 4.1 Growth in Callus Tissue and Suspension Cultures.- 4.2 Growth in Organ Cultures and Protoplast Cultures.- 5. The Growth of Nematodes in Tissue Culture.- 5.1 Infection of Organ Cultures.- 5.2 Infection of Callus-tissue Cultures.- 6. Conclusions.- References.- 8. Genetics of Host-Parasite Interactions.- 1. Introduction.- 2. Inheritance of Resistance and Virulence.- 2.1 Inheritance of Resistance in Flax (Linum usitatissimum) to Melampsora lini.- 2.2 Inheritance of Virulence in Melampsora lini.- 2.3 Basic Genetic Patterns of Host-Parasite Relationships.- 3. Constitutive or Adaptive Function of the Genes Controlling Specificity.- 4. Specific Interactions for Compatibility or Incompatibility.- 5. Perspective of Evolution of Different Types of Interactions.- 6. Use of Genetic Arguments in Studies of Host-Parasite Relationships.- 7. Discussion.- References.- Author Index.- Index of Microorganisms and Nematodes.- List of Symbols and Abbreviations.