Fungal pathogenesis in plants and crops/ Molecular biology and host defence mechanisms P Vidhyasekaran

PERCEPTION AND TRANSDUCTION OF PLANT SIGNALS IN PATHOGENS Introduction Signaling and Transduction Systems in ''First Touch'' and Adhesion of Fungal SporesSignaling in Fungal Spore GerminationSignaling 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 ElicitorsProtein Peptide ElicitorsGlycoprotein ElicitorsLipid ElicitorsToxins as Elicitor MoleculesPlant Cell Wall-Degrading Enzymes as ElicitorsRace-Specific and Cultivar-Specific ElicitorsSpecificity of General ElicitorsEndogenous Oligogalacturonide ElicitorsMultiple Elicitors May Be Needed to Activate Defense ResponsesAvailability of Fungal Elicitors at the Site of Fungal Invasion in PlantsReceptors for Elicitor Signals in Plant Cell MembraneCalcium Ion May Act as Second MessengerPhosphorylation of Proteins as a Component in Signal Transduction SystemMitogen-Activated Protein Kinase Cascades in Signal TransductionPhospholipid-Signaling SystemAnion Channels in Signal TransductionExtracellular Alkalinization and Cytoplasmic Acidification in Signaling SystemReactive Oxygen Species in Signal TransductionNitric Oxide in Signal TransductionSalicylic Acid-Signaling SystemJasmonate-Signaling PathwayRole of Systemin in Signal Transduction SystemEthylene-Dependent Signaling PathwayAbscisic Acid SignalingFatty Acids as Systemic Signal MoleculesOther Signaling SystemsNetwork and Interplay of Signaling PathwaysInduction of Defense Genes May Require Different Signal Transduction SystemsPerception and Transduction of Pathogen Signals in Plants Leading to SusceptibilitySignaling Systems in Susceptible InteractionsConclusionReferencesDISEASE RESISTANCE AND SUSCEPTIBILITY GENES IN SIGNAL PERCEPTION AND EMISSIONIntroduction Molecular Structure of Resistance Genes Classification of Resistance Genes based on Molecular Structure of R Gene-Encoded ProteinsMolecular Structure of Recessive Genes Perception of Pathogen Signals by Resistance Genes Activation of R Protein and Emission of Signals to Other Components in the CellDownstream Components of R Gene Signaling SystemsDownstream Signaling Events in R Gene-Mediated Resistance Susceptibility Genes in Signal Transduction Conclusion References CELL DEATH PROGRAMS DURING FUNGAL PATHOGENESISIntroduction Cell Death in Resistant Interactions Molecular Mechanism of Induction of Hypersensitive Cell DeathMolecular Mechanism of Induction of Spontaneous Cell DeathMolecular Mechanism of Induction of Runaway Cell DeathRole of Cell Death in Induction of Systemic Acquired ResistanceSusceptibility-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 BarrierGenes 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 BarrierFungal Hemicellulases in Plant Cell Wall Degradation Degradation of Cell Wall Structural ProteinsRequirement of Several Cell Wall-Degrading Enzymes to Degrade the Complex-Natured Cell WallProduction of Suitable Enzymes in Appropriate Sequence by Fungal Pathogens Reinforcement of Host Cell Wall during Fungal Invasion Papillae Suppress Fungal PenetrationCallose Deposition in Cell Wall How Do Pathogens Overcome the Papillae and Callose Barriers? Cell Wall-Bound Phenolics and LigninsSuberization during Fungal Pathogenesis Deposition of Mineral Elements in Host Cell Wall in Response to Fungal InvasionConclusion 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 PrecursorsSecretion of PR Proteins PR Proteins May Be Involved in Inhibition of Pathogen DevelopmentPR Proteins May Be Involved in Triggering Disease ResistanceHow Do Pathogens Overcome Fungitoxic PR Proteins of the Host?Conclusion References EVASION AND DETOXIFICATION OF SECONDARY METABOLITESIntroduction Chemical Structural Classes of Phytoalexins Biosynthesis of Isoflavonoid Phytoalexins Biosynthesis of Flavanone Phytoalexins Biosynthesis of Coumarin Phytoalexins Biosynthesis of Stilbene Phytoalexins Biosynthesis of Terpenoid PhytoalexinsBiosynthesis of Indole-Based Sulfur-Containing Phytoalexins Biosynthesis of Alkaloid Phytoalexins Site of Synthesis of PhytoalexinsPhytoalexins 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 PhytoanticipinsGlucosinolates as PhytoanticipinsCyanogenic Glucosides DienesConclusion References TOXINS IN DISEASE SYMPTOM DEVELOPMENT Introduction Importance of Toxins in Disease Development Toxins Suppress Host-Defense MechanismsToxins Cause Cell Membrane Dysfunction How Do Pathogens Induce Membrane Dysfunction only in Susceptible Hosts? Conclusion References Index