Biochemical Aspects of Plant-Parasite Relationships

Biochemical Aspects of Plant-Parasite Relationships is a collection of papers from the Phytochemical Society Symposium of the same subject held at Hull in April 1975. This collection discusses biochemical research on the mechanisms involved in the invasion of plants by pathogens, the production of disease symptoms, and the mechanisms occurring in plant resistance against the invading microorganisms. Some papers discuss the genetics of fungal-plant interactions and the structural features of both infection and resistance processes, Such genetic interactions and structural features point to a biochemical reason for the plant-parasite interaction. Several attempts to correlate production of a cell wall degrading enzyme in vitro by a pathogen's virulence have shown great differences between in vitro and in vivo environments. One paper cites as an example the pathogens which produce both pectic hydrolases and lyases: the type of enzyme that is found to predominate often is actually associated with the pH of the environment. One paper also investigates nucleic acid transfer and the possible role of RNA in the host-parasite specificity. This collection can prove beneficial for microbiologists, biochemists, biotechnologists, plant biologists, and academicians connected with the biological sciences.

Contenu

Contributors

Preface

Chapter 1 Some Observations on Leaf Surfaces During the Early Stages of Infection by Fungi

I. Introduction

II. The Pre-Penetration Stages of Infection of Leaves

III. The Arrival of Spores on Leaves

IV. Adhesion of Spores on Leaves

V. External Growth Prior to Penetration

VI. Rain-Water Washing Leaf Surfaces

VII. Pollen on Leaves and Infection

References

Chapter 2 Some Interactions in Soil Between Plants, Sclerotium-Forming Fungi and Other Microorganisms

I. Introduction

II. The Nature of Fungal Sclerotia

III. Host-Stimulated Germination of Sclerotia

IV. The Effect of Fungal Sclerotia on the Soil Microflora

Acknowledgements

References

Chapter 3 Development and Use of Some Genetically Controlled Lines for Studies of Host-Parasite Interactions

I. Introduction

II. Host Lines

A. Nearly-Isogenic Lines

B. Chromosome Substitution Lines

C. Genetically Diverse Host Lines

III. Pathogen Lines

IV. Conclusions

Acknowledgements

References

Chapter 4 Structural Aspects of Infection by Biotrophic Fungi

I. Introduction

II. The Infection of Lettuce by Bremia Lactucae

A. Pre-Penetration

B. Penetration

C. Intracellular Infection Structures

III. Discussion

A. Alteration of the Metabolism of the Host

B. Molecular Exchange

C. Incompatibility

References

Chapter 5 Plant Cell Wall Hydrolysis by Pathogens

I. Introduction

II. The Plant Cell Wall: A Current Concept

III. Enzymes that Cleave Cell Wall Polysaccharides

A. Pectic Enzymes

B. Hemicellulases and Cellulases

IV. Regulation of Production of Polysaccharidases by Pathogens

V. Enzymatic Degradation of Cell Walls

A. Decomposition of Isolated Walls

B. Decomposition of Host Cell Walls in Infected Tissues

VI. Enzymatic Basis of Tissue Maceration and its Consequences

VII. Conclusions

References

Chapter 6 Killing of Protoplasts

I. Introduction

II. Relation Between Cell Separation and Protoplast Death

III. Action of Pectic Enzymes on Parenchyma

IV. Effect of Other Enzymes on Parenchyma

V. Effects of Plasmolysis

VI. Effects of Enzymes Other than Pectic Enzymes

VII. Killing of Protoplasts other than by Pectic Enzymes

VIII. Other Causes of Death of Protoplasts

IX. Consequences of Protoplast Death

References

Chapter 7 Hormonal Involvement in Metabolism of Host-Parasite Interactions

I. Introduction

II. Hormones and Pathogenesis

III. Hormonal Changes in Diseases Caused by Biotrophic Organisms

A. Respiration and Host Growth

. IAA Decarboxylation and Disease Resistance

C. Peroxidase Changes

D. Properties of Isozyme 9

E. Cytokinins and Translocation

F. Other Hormones

IV. Present Outlook

Acknowledgements

References

Chapter 8 Toxins of Plant Pathogenic Bacteria and Fungi

I. Introduction

II. Helminthosporoside

III. Some Other Host-Specific Toxins

A. H. Victoriae and P. Circinata Toxins

B. A. Kikuchiana Toxin

C. H. Carbonum Toxin

D. H. Maydis Toxins

E. P. Maydis Toxin

F. Alternariolide

IV. Stemphylin

V. Toxic Glycopeptides and Polysaccharides

VI. Fusicoccin

VII. Some Amino Acid Derived Bacterial Toxins

A. Tabtoxins

B. Phaseotoxins

C. Rhizobitoxine

D. Syringomycin

VIII. Non Host-Specific Alternaria Toxins

IX. Concluding Comments

Acknowledgements

References

Chapter 9 Structural Features of Resistance to Plant Diseases

I. Introduction

II. Inoculum Deposition

III. Entry of the Pathogen

A. Direct Entry

B. Entry through Natural Openings

IV. Colonization and Sporulation

V. Conclusions

References

Chapter 10 Pre-Existing Antimicrobiol Substances in Plants and their Role in Disease Resistance

I. Introduction

II. Tulipalin and Tuliposid

III. Wyerone

IV. Phenolic Compounds

A. Pyrocatechol and Protocatechuic Acid

B. Phloridzin and Phloretin

V. Antifungal Compounds in Wood

VI. Antifungal Compounds in Gramineae

VII. Concluding Remarks

References

Chapter 11 Current Perspectives in Research on Phytoalexins

I. Definitions and General Problems

II. Phytoalexins in the Higher Plants

A. Characterized Compounds

B. De Novo Synthesis or Release from Precursors

C. Restriction to Some Plant Families

III. Roles of Phytoalexins in Hypersensitivity and Lesion Limitation

IV. The Induction of Phytoalexin Formation

Acknowledgements

References

Chapter 12 Terpenoid Phytoalexins

I. Introduction

II. Terpenoids Produced in Infected Potato

III. Relationship of Terpenoid Metabolism to Disease Resistance

IV. Nature of the Initiator of Rishitin Biosynthesis

V. Stability of Terpenoids Produced in Infected Potato Slices

VI. Conclusion

Acknowledgements

References

Chapter 13 Isoflavonoid Phytoalexins

I. Introduction

II. Types and Sources of Isoflavonoid Phytoalexins

III. Biosynthesis of Isoflavonoids

. Formation of the C1 5 Skeleton

. The Point of Divergence Between Flavonoid and Isoflavonoid Biosynthesis

C. Biosynthetic Relationships Among Isoflavonoids

D. Hydroxylation, Methylation, and Prenylation of Isoflavonoids

E. Turnover of Isoflavonoids in Higher Plants

IV. Induction

A. Inducers

B. Localization of Phytoalexin Accumulation

C. Mechanism of Induction

V. Biological Action Spectrum

A. Activity Against Fungi

B. Activity Against Other Organisms

VI. Cytological and Physiological Effects on Fungi

VII. Structural Requirements for Antifungal Activity

VIII. Fungal Metabolism of the Isoflavonoid Phytoalexins

A. Identity of Fungal Metabolites of Phytoalexins

B. Enzymology

C. Metabolism and Tolerance

D. Fungal Metabolism of the Isoflavonoid Phytoalexins In Situ

IX. Isoflavonoid Phytoalexins and Pathogenesis

A. Differential Synthesis

B. Differential Sensitivity

C. Additional Considerations

X. Conclusions

Acknowledgements

References

Chapter 14 Lignification in Infected Tissue

I. Introduction

II. Lignification in the Solanaceae in Response to Fungal Infection

A. The Response of Potato Tu…