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Molecular Plant Immunity

Molecular Plant Immunity

Guido Sessa (Editor)

ISBN: 978-1-118-48145-5

Oct 2012

304 pages



Molecular Plant Immunity provides an integrated look at both well-established and emerging concepts in plant disease resistance providing the most current information on this important vitally important topic within plant biology. Understanding the molecular basis of the plant immune system has implications on the development of new varieties of sustainable crops, understanding the challenges plant life will face in changing environments, as well as providing a window into immune function that could have translational appeal to human medicine.

Molecular Plant Immunity opens with chapters reviewing how the first line of plant immune response is activated followed by chapters looking at the molecular mechanisms that allow fungi, bacteria, and oomycetes to circumvent those defenses. Plant resistance proteins, which provide the second line of plant immune defense, are then covered followed by chapters on the role of hormones in immunity and the mechanisms that modulate specific interaction between plants and viruses. The final chapters look at model plant-pathogen systems to review interaction between plants and fungal, bacterial, and viral pathogens.

 Written by a leading team of international experts, Molecular Plant Immunity will provide a needed resource to diverse research community investigated plant immunity.

Contributors xi

Preface xv

Chapter 1 The Rice Xa21 Immune Receptor Recognizes a Novel Bacterial Quorum Sensing Factor 1
Chang Jin Park and Pamela C. Ronald

Introduction 1

Plants and Animal Immune Systems 2

A Plethora of Immune Receptors Recognize Conserved Microbial Signatures 2

Ax21 Conserved Molecular Signature 3

Non-RD Receptor Kinase Xa21 8

XA21-Mediated Signaling Components 11

Cleavage and Nuclear Localization of the Rice XA21 Immune Receptor 13

Regulation in the Endoplasmic Reticulum: Quality Control of XA21 14

Systems Biology of the Innate Immune Response 15

Acknowledgments 16

References 16

Chapter 2 Molecular Basis of Effector Recognition by Plant NB-LRR Proteins 23
Lisong Ma, Harrold A. van den Burg, Ben J. C. Cornelissen, and Frank L. W. Takken

Introduction 23

Building Blocks of NB-LRRs; Classification and Structural Features of Subdomains 24

Putting the Parts Together: Combining the Domains to Build a Signaling Competent NB-LRR Protein 29

Stabilization and Accumulation of NB-LRR Proteins: Their Maturation and Stabilization 30

When the Pathogen Attacks: Perception and Signaling by NB-LRR Proteins 33

Conclusion 35

Acknowledgments 35

References 36

Chapter 3 Signal Transduction Pathways Activated by R Proteins 41
Gitta Coaker and Douglas Baker

Introduction 41

R Protein Stability 42

Genetic Separation of CC and TIR-NB-LRR Signaling 42

NB-LRRs Exhibit Modular Structure and Function 44

Subcellular Localization of NB-LRRs 45

NB-LRRs Can Function in Pairs 47

Common Immune Signaling Events Downstream of R Protein Activation 48

Conclusion 50

Acknowledgments 50

References 50

Chapter 4 The Roles of Salicylic Acid and Jasmonic Acid in Plant Immunity 55
Pradeep Kachroo and Aardra Kachroo

Introduction 55

Biosynthesis of SA 55

Derivatives of SA 57

SA and Systemic Acquired Resistance 58

SA Signaling Pathway 60

Jasmonates Mediate Plant Immunity 62

JA Biosynthetic Mutants Are Altered in Microbial Defense 63

Receptor Protein Complex Perceives JA 65

Transcription Factors Regulate JA-Derived Signaling 66

JA Regulates Defense Gene Expression 68

Conclusion 68

Acknowledgments 68

References 69

Chapter 5 Effectors of Bacterial Pathogens: Modes of Action and Plant Targets 81
Feng Feng and Jian-Min Zhou

Introduction 81

Overview of Plant Innate Immunity 81

Overview of Type III Effectors 83

Host Targets and Biochemical Functions 86

Conclusion 99

Acknowledgments 99

References 99

Chapter 6 The Roles of Transcription Activator–Like (TAL) Effectors in Virulence and Avirulence of Xanthomonas 107
Aaron W. Hummel and Adam J. Bogdanove

Introduction 107

TAL Effectors Are Delivered into and May Dimerize in the Host Cell 107

TAL Effectors Function in the Plant Cell Nucleus 108

AvrBs4 Is Recognized in the Plant Cell Cytoplasm 109

TAL Effectors Activate Host Gene Expression 109

Central Repeat Region of TAL Effectors Determines DNA Binding Specificity 110

TAL Effectors Wrap Around DNA in a Right-Handed Superhelix 111

TAL Effector Targets Include Different Susceptibility and Candidate Susceptibility Genes 112

MtN3 Gene Family Is Targeted by Multiple TAL Effectors 114

Promoter Polymorphisms Prevent S Gene Activation to Provide Disease Resistance 115

Nature of the Rice Bacterial Blight Resistance Gene xa5 Suggests TAL Effector Interaction With Plant Transcriptional Machinery 115

Executor R Genes Exploit TAL Effector Activity for Resistance 116

Diversity of TAL Effectors in Xanthomonas Populations Is Largely Unexplored 117

TAL Effectors Are Useful Tools for DNA Targeting 118

Conclusion 118

References 119

Chapter 7 Effectors of Fungi and Oomycetes: Their Virulence and Avirulence Functions and Translocation From Pathogen to Host Cells 123
Brett M. Tyler and Thierry Rouxel

Introduction 123

Plant-Associated Fungi and Oomycetes 125

Identification of Fungal and Oomycete Effectors 126

Defensive Effectors: Effectors That Interfere With Plant Immunity 137

Offensive Effectors: Effectors That Debilitate Plant Tissue 146

Effectors That Contribute to Fitness via Unknown Mechanisms 149

Entry of Intracellular Effectors 149

Genome Location and Consequences for Adaptation/Dispensability 152

Conclusion 153

Acknowledgments 154

References 154

Chapter 8 Plant-Virus Interaction: Defense and Counter-Defense 169
Amy Wahba Foreman, Gail J. Pruss, and Vicki Vance

Introduction 169

RNA Silencing as an Antiviral Defense Pathway – the Beginning of the Story 169

Small Regulatory RNA Biogenesis and Function 172

The Silencing Mafia – the Protein Families 174

Defense: Antiviral RNA Silencing Pathways 177

Counter-Defense: Viral Suppressors of Silencing and Their Targets 178

Viral Suppressors of Silencing and Endogenous Small Regulatory RNA Pathways 181

References 182

Chapter 9 Molecular Mechanisms Involved in the Interaction Between Tomato and Pseudomonas syringae pv. tomato 187
Andr´e C. Vel´asquez and Gregory B. Martin

Introduction 187

PAMP-Triggered Immunity in Solanaceae 188

Pseudomonas syringae pv. tomato Virulence Mechanisms 192

Effector-Triggered Immunity in Solanaceae 197

Races of Pseudomonas syringae pv. tomato 200

ETI Is Involved in Nonhost Resistance to Pseudomonas syringae Pathovars 200

ETI Signaling Pathways in Solanaceae 201

Conclusion 203

Acknowledgments 204

References 204

Chapter 10 Cladosporium fulvum–Tomato Pathosystem: Fungal Infection Strategy and Plant Responses 211
Bilal O¨ kmen and Pierre J. G. M. de Wit

Introduction 211

History of the Interaction Between C. fulvum and Tomato 212

Compatible and Incompatible Interactions 212

Cf-Mediated Downstream Signaling 219

Effectors in Other Fungi with Similar Infection Strategies 220

Conclusion 221

References 221

Chapter 11 Cucumber Mosaic Virus–Arabidopsis Interaction: Interplay of Virulence Strategies and Plant Responses 225
Jack H. Westwood and John P. Carr

Introduction 225

Biology of CMV 226

Host Resistance Responses to Virus Infection 230

Targeting of Host Factors by the Virus 236

Phenomenon of Cross-Protection 237

Functions of SA in Antiviral Defense 237

Metabolic Responses to CMV Infection 239

Vector-Mediated Transmission 240

Conclusion 242

Acknowledgments 242

References 243

Chapter 12 Future Prospects for Genetically Engineering Disease-Resistant Plants 251
Yan-Jun Chen, Michael F. Lyngkjær, and David B. Collinge

Introduction 251

Targets for Second-Generation Transgenic Strategies for Resistance 252

Hormones 253

Defense Modulation 256

Transcription Factors 260

Promoters for Transgenic Disease Resistance 265

Implementation of Transgenic Resistance in the Field 266

Why Choose a Transgenic Approach? 267

Conclusion 269

Acknowledgments 269

References 269

Index 277