Fungal pathogenesis in plants and crops: molecular biology and host defense mechanisms. (1997)

PERCEPTION AND TRANSDUCTION OF PLANT SIGNALS IN PATHOGENS Introduction Signaling and Transduction Systems in First Touch and Adhesion of Fungal Spores Signaling in Fungal Spore Germination Signaling in Differentiation of Germ Tubes into Infection Structures Signal Transduction in Fungal Pathogenesis Genes Involved in Formation of Infection Structures Signals in Fungal Infection Process Conclusion References PERCEPTION AND TRANSDUCTION OF PATHOGEN SIGNALS IN PLANTS Introduction What Are Elicitors? Oligosaccharide Elicitors Protein Peptide Elicitors Glycoprotein Elicitors Lipid Elicitors Toxins as Elicitor Molecules Plant Cell Wall-Degrading Enzymes as Elicitors Race-Specific and Cultivar-Specific Elicitors Specificity of General Elicitors Endogenous Oligogalacturonide Elicitors Multiple Elicitors May Be Needed to Activate Defense Responses Availability of Fungal Elicitors at the Site of Fungal Invasion in Plants Receptors for Elicitor Signals in Plant Cell Membrane Calcium Ion May Act as Second Messenger Phosphorylation of Proteins as a Component in Signal Transduction System Mitogen-Activated Protein Kinase Cascades in Signal Transduction Phospholipid-Signaling System Anion Channels in Signal Transduction Extracellular Alkalinization and Cytoplasmic Acidification in Signaling System Reactive Oxygen Species in Signal Transduction Nitric Oxide in Signal Transduction Salicylic Acid-Signaling System Jasmonate-Signaling Pathway Role of Systemin in Signal Transduction System Ethylene-Dependent Signaling Pathway Abscisic Acid Signaling Fatty Acids as Systemic Signal Molecules Other Signaling Systems Network and Interplay of Signaling Pathways Induction of Defense Genes May Require Different Signal Transduction Systems Perception and Transduction of Pathogen Signals in Plants Leading to Susceptibility Signaling Systems in Susceptible Interactions Conclusion References DISEASE RESISTANCE AND SUSCEPTIBILITY GENES IN SIGNAL PERCEPTION AND EMISSION Introduction Molecular Structure of Resistance Genes Classification of Resistance Genes based on Molecular Structure of R Gene-Encoded Proteins Molecular Structure of Recessive Genes Perception of Pathogen Signals by Resistance Genes Activation of R Protein and Emission of Signals to Other Components in the Cell Downstream Components of R Gene Signaling Systems Downstream Signaling Events in R Gene-Mediated Resistance Susceptibility Genes in Signal Transduction Conclusion References CELL DEATH PROGRAMS DURING FUNGAL PATHOGENESIS Introduction Cell Death in Resistant Interactions Molecular Mechanism of Induction of Hypersensitive Cell Death Molecular Mechanism of Induction of Spontaneous Cell Death Molecular Mechanism of Induction of Runaway Cell Death Role of Cell Death in Induction of Systemic Acquired Resistance Susceptibility-Related Cell Death Molecular Mechanisms in Induction of Cell Death in Susceptible Interactions What Is the Function of Cell Death in Fungal Pathogenesis? Conclusion References CELL WALL DEGRADATION AND FORTIFICATION Introduction Structure of Cuticle Penetration of Epicuticular Waxy Layer by Pathogens Production of Cutinases to Breach Cuticle Barrier Genes Encoding Cutinases Plant Signals Triggering Fungal Cutinases Importance of Cutinases in Penetration of Cuticle Cutinases as Virulence Pathogenicity Factors Melanins in Fungal Penetration of Cuticle Barrier Degradation of Pectic Polysaccharides Pathogens Produce Cellulolytic Enzymes to Breach Cell Wall Barrier Fungal Hemicellulases in Plant Cell Wall Degradation Degradation of Cell Wall Structural Proteins Requirement of Several Cell Wall-Degrading Enzymes to Degrade the Complex-Natured Cell Wall Production of Suitable Enzymes in Appropriate Sequence by Fungal Pathogens Reinforcement of Host Cell Wall during Fungal Invasion Papillae Suppress Fungal Penetration Callose Deposition in Cell Wall How Do Pathogens Overcome the Papillae and Callose Barriers? Cell Wall-Bound Phenolics and Lignins Suberization during Fungal Pathogenesis Deposition of Mineral Elements in Host Cell Wall in Response to Fungal Invasion Conclusion References INDUCTION AND EVASION OF PATHOGENESIS-RELATED PROTEINS Introduction Multiplicity of PR Proteins Classification of PR Proteins Induction of PR Proteins during Fungal Pathogenesis Genes Encoding PR Proteins Transcription of PR Genes Signals Involved in Transcriptional Induction of PR Genes PR Proteins Are Synthesized as Larger Precursors Secretion of PR Proteins PR Proteins May Be Involved in Inhibition of Pathogen Development PR Proteins May Be Involved in Triggering Disease Resistance How Do Pathogens Overcome Fungitoxic PR Proteins of the Host? Conclusion References EVASION AND DETOXIFICATION OF SECONDARY METABOLITES Introduction Chemical Structural Classes of Phytoalexins Biosynthesis of Isoflavonoid Phytoalexins Biosynthesis of Flavanone Phytoalexins Biosynthesis of Coumarin Phytoalexins Biosynthesis of Stilbene Phytoalexins Biosynthesis of Terpenoid Phytoalexins Biosynthesis of Indole-Based Sulfur-Containing Phytoalexins Biosynthesis of Alkaloid Phytoalexins Site of Synthesis of Phytoalexins Phytoalexins Are Fungitoxic How Do Pathogens Overcome the Antifungal Phytoalexins? Chemical Structural Classes of Phytoanticipins Phenolics as Phytoanticipins Toxicity of Phenolics to Pathogens How Does Pathogen Overcome the Antifungal Phenolics? Saponins as Phytoanticipins Glucosinolates as Phytoanticipins Cyanogenic Glucosides Dienes Conclusion References TOXINS IN DISEASE SYMPTOM DEVELOPMENT Introduction Importance of Toxins in Disease Development Toxins Suppress Host-Defense Mechanisms Toxins Cause Cell Membrane Dysfunction How Do Pathogens Induce Membrane Dysfunction only in Susceptible Hosts? Conclusion References Index