Part 1 of ebook Plant pathology (Fifth edition) provide readers with content about: general aspects; history of plant pathology and early significant plant diseases; losses caused by plant diseases; parasitism and disease development; effects of pathogens on plant physiological functions; genetics of plant disease; how pathogens attack plants; how plants defend themselves against pathogens; environmental effects on the development of infectious plant disease;...
Fifth Edition PLANT PATHOLOGY Fifth Edition PLANT PATHOLOGY GEORGE N AGRIOS Department of Plant Pathology University of Florida Amsterdam • Boston • Heidelberg • London • New York • Oxford Paris • San Diego • San Francisco • Singapore • Sydney • Tokyo Publisher Associate Acquisitions Editor Project Manager Marketing Manager Cover Design Composition Cover Printer Interior Printer Dana Dreibelbis Kelly D Sonnack Troy Lilly Linda Beattie Eric DeCicco SNP Best-set Typesetter Ltd., Hong Kong RR Donnelley & Sons Company RR Donnelley & Sons Company Elsevier Academic Press 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA 525 B Street, Suite 1900, San Diego, California 92101-4495, USA 84 Theobald’s Road, London WC1X 8RR, UK This book is printed on acid-free paper Copyright © 2005, 1997, 1988, 1978, 1969 Elsevier Inc All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone: (+44) 1865 843830, fax: (+44) 1865 853333, e-mail: permissions@elsevier.com.uk You may also complete your request on-line via the Elsevier homepage (http://elsevier.com), by selecting “Customer Support” and then “Obtaining Permissions.” Library of Congress Cataloging-in-Publication Data Agrios, George N., 1936– Plant pathology / George Agrios — 5th ed p cm Includes bibliographical references and index ISBN 0-12-044565-4 (hardcover: alk paper) Plant diseases I Title SB731.A35 2004 571.9¢2 — dc22 2004011924 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library For all information on all Elsevier Academic Press Publications visit our Web site at www.books.elsevier.com Printed in the United States of America 04 05 06 07 08 09 This, the 5th and probably the last edition of Plant Pathology by me, is dedicated: To the memory of my parents, Nikolas and Olga, who, in spite of their limited education, sacrificed everything to give me the most and best education possible To the memory of Dr Walter F Buchholtz, my major professor at Iowa State University, who challenged me before I had even taught my first lecture to “write my own textbook on Plant Pathology” To my sisters, Dimitra and Evangelia, who have been there for me forever and who also sacrificed some of their interests for my benefit To my wife, Annette, whose love and support have been the most precious things to me throughout our life together, and who helped me in many facets of preparation of this and of previous editions of Plant Pathology To my daughters-in-law, Betsy and Vivynne, who, by joining our family, added beauty, love, enjoyment, and four wonderful grandchildren Finally, to Mark and Maximos, our youngest grandchildren, who, someday, when they read their names in the book, may be reassured of “Granpa’s” love for them, and may feel proud of their grandfather Contents Preface xxi Photo credits xxiii About the Author xxvi The Expanding Role of Fungi as Causes of Plant Disease 21 The Discovery of the Other Causes of Infectious Diseases 23 Nematodes 23; Protozoan Myxomycetes 24; Bacteria 24; Viruses Protozoa 25; Mollicutes 26; Viroids 26; Serious Plant Diseases of Unknown Etiology 26; Koch’s Postulates 26; Viruses, Viroids, and Prions 27 part one GENERAL ASPECTS Losses Caused by Plant Diseases Plant diseases reduce the quantity and quality of plant produce 29 chapter one INTRODUCTION Prologue: The Issues Plants and Disease White, Downey, and Dry Vineyards — Bring on the Bordeaux! 30 Plant diseases may limit the kinds of plants and industries in an area 32 Familiar trees in the landscape: going, going, gone (Box) 32 The Concept of Disease in Plants Types of Plant Diseases History of Plant Pathology and Early Significant Plant Diseases Introduction 29 Chestnuts, Elms, and Coconut Palm Trees — Where have they gone? 32–35 Plant diseases may make plants poisonous to humans and animals 37 Plant Diseases as the Wrath of Gods — Theophrastus (Box) 9; Mistletoe Recognized as the First Plant Pathogen (Box) 14; Plant Diseases as the Result of Spontaneous Generation (Box) 16; Biology and Plant Pathology in Early Renaissance (Box) 16; Potato Blight — Deadly Mix of Ignorance and Politics (Box) 19 Ergot, Ergotism, and LSD: a Bad Combination (Box) Mycotoxins and Mycotoxicoses (Box) 39 Plant diseases may cause financial losses 41 The Insect — Pathogen Connection: Multifaceted and Important (Box) 42 vii 37; viii CONTENTS Plant Pathology in the 20th Century Early Developments 45 45 The Descriptive Phase 45; The Experimental Phase 46; The Etiological Phase 46; The Search for Control of Plant Diseases 46 The Main Areas of Progress 47 Chemical Control of Plant Diseases 47; Appearance of Pathogen Races Resistant to Bactericides and Fungicides 48; Public Concern about Chemical Pesticides 48; Alternative Controls for Plant Diseases 49; Interest in the Mechanisms by Which Pathogens Cause Disease 50; The Concept of Genetic Inheritance of Resistance and Pathogenicity 52; Epidemiology of Plant Disease Comes of Age 53 56 Plant Biotechnology — The Promise and the Objections (Box) 56; Food Safety (Box) 58; Bioterrorism, Agroterrorism, Biological Warfare, etc Who, What, Why (Box) 59 Worldwide Development of Plant Pathology as a Profession 60 International Centers for Agricultural Research 60; Trends in Teaching and Training 61; Plant Disease Clinics 62; The Practice and Practitioners of Plant Pathology 63; Certification of Professional Plant Pathologists 63; Plant Pathology as a Part of Plant Medicine; the Doctor of Plant Medicine Program (Box) 64 Plant Pathology’s Contribution to Crops and Society 65 Some Historical and Present Examples of Losses Caused by Plant Diseases 65 Plant Diseases and World Crop Production 65 Crop Losses to Diseases, Insects and Weeds 66 Pesticides and Plant Diseases 69 Basic Procedures in the Diagnosis of Plant Diseases 71 Pathogen or Environment Infectious Diseases 72 71 Parasitic Higher Plants 72; Nematodes 72; Fungi and Bacteria: Fungi 72; Bacteria and Mollicutes 72; Viruses and Viroids 73; More than One Pathogen 73 Noninfectious Diseases 73 PARASITISM AND DISEASE DEVELOPMENT Parasitism and Pathogenicity 77 Host Range of Pathogens 78 Development of Disease in Plants 79 Stages in the Development of Disease: The Disease Cycle 80 80 Inoculation 80; Inoculum 80; 54 Aspects of Applied Plant Pathology chapter two Inoculation Plant Pathology Today and Future Directions 54 Molecular Plant Pathology Identification of a Preciously Unknown Disease: Koch’s Postulates 74 Types of Inoculum 80; Sources of Landing or Arrival of Inoculum 81 Prepenetration Phenomena 82 Attachment of Pathogen to Host 82; Spore Germination and Perception of the Host Surface 82; Appressorium Formation and Maturation 85; Recognition between Host and Pathogen 86; Germination of Spores and Seeds 86; Hatching of Nematode Eggs 87 Penetration 87 Direct Penetration through Intact Plant Surfaces 87; Penetration through Wounds 88; Penetration through Natural Openings 88 Infection 89 Infection 89; Invasion 91; Growth and Reproduction of the Pathogen (Colonization) Dissemination of the Pathogen 91 96 Dissemination by Air 96; Dissemination by Water 97; Dissemination by Insects, Mites, Nematodes, and Other Vectors 97; Dissemination by Pollen, Seed, Transplants, Budwood, and Nursery Stock 100; Dissemination by Humans 100 Overwintering and/or Oversummering of Pathogens 100 Relationships between Disease Cycles and Epidemics 102 chapter three EFFECTS OF PATHOGENS ON PLANT PHYSIOLOGICAL FUNCTIONS Effects of Pathogens on Photosynthesis 106 Effect of Pathogens on Translocation of Water and Nutrients in the Host Plant 106 ix CONTENTS Interference with Upward Translocation of Water and Inorganic Nutrients 106 Effect on Absorption of Water by Roots 108 Effect on Translocation of Water through the Xylem 108 Effect on Transpiration 108 Interference with the Translocation of Organic Nutrients through the Phloem 113 Effect of Pathogens on Host Plant Respiration 115 Respiration of Diseased Plants 117 Effect of Pathogens on Permeability of Cell Membranes 118 Effects of Pathogens on Transcription and Translation 118 Effect on Transcription Translation 119 119; Effect on Effect of Pathogens on Plant Growth Effect of Pathogens on Plant Reproduction 121 119 chapter four GENETICS OF PLANT DISEASE Introduction 125 Genes and Disease 126 Variability in Organisms Mechanisms of Variability 128 128 General Mechanisms: Mutation 129; Recombination 129; Gene and Genotype Flow among Plant Pathogens 130; Population Genetics, Genetic Drift, and Selection 130; Life Cycles — Reproduction — Mating Systems — Outcrossing 131; Pathogen Fitness 131; Specialized Mechanisms of Variability in Pathogens 131; Sexual-like Processes in Fungi Heterokaryosis 131; Parasexualism 132; Vegetative Incompatibility 132; Heteroploidy 132; Sexual-like Processes in Bacteria and Horizontal Gene Transfer 132; Genetic Recombination in Viruses 133; Loss of Pathogen Virulence in Culture 133 Stages of Variation in Pathogens 134 Types of Plant Resistance to Pathogens 134 True Resistance: Partial, Quantitative, Polygenic, or Horizontal Resistance — R-Gene Resistance, Monogenic, or Vertical Resistance 136 Apparent Resistance 137 Disease Escape 137; Tolerance to Disease 139 Genetics of Virulence in Pathogens and of Resistance in Host Plants 139 The Nature of Resistance to Disease 142 Pathogenicity Genes in Plant Pathogens 142 Genes Involved in Pathogenesis and Virulence by Pathogens 142 Pathogenicity Genes of Fungi controlling: Production of Infection Structures 144 Degradation of Cuticle and Cell Wall 144 Secondary Metabolites 145 Fungal Toxins 146 Pathogenicity Signaling Systems 146 Pathogenicity Genes in Plant Pathogenic Bacteria 146 Bacterial Adhesion to Plant Surfaces 146 Secretion Systems 147 Enzymes that Degrade Cell Walls 147 Bacterial Toxins as Pathogenicity Factors 148 Extracellular Polysaccharides as Pathogenicity Factors 148 Bacterial Regulatory Systems and Networks 148 Sensing Plant Signaling Components 149 Other Bacterial Pathogenicity Factors 149 Pathogenicity Genes in Plant Viruses 149 Functions Associated with the Coat Protein 149 Viral Pathogenicity Genes 150 Nematode Pathogenicity Genes 150 Genetics of Resistance through the Hypersensitive Response 151 Pathogen-Derived Elicitors of Defense Responses in Plants 151; Avirulence (avr) Genes: One of the Elicitors of Plant Defense Responses 151; Characteristics of avr Gene-Coded Proteins 153; Their Structure and Function Role of avr Genes in Pathogenicity and Virulence 154; hrp Genes and the Type III Secretion System 155 Resistance (R) Genes of Plants 155 Examples of R Genes 156 How Do R Genes Confer Resistance? Evolution of R Genes 157 Other Plant Genes for Resistance to Disease 158 157 ... Translation 11 9 11 9; Effect on Effect of Pathogens on Plant Growth Effect of Pathogens on Plant Reproduction 12 1 11 9 chapter four GENETICS OF PLANT DISEASE Introduction 12 5 Genes and Disease 12 6 Variability... Microbial Toxins in Plant Disease 19 0 Toxins That Affect a Wide Range of Host Plants 19 0; Tabtoxin 19 1; Phaseolotoxin 19 1; Tentoxin 19 1; Cercosporin 19 2; Other Nonhost-Specific Toxins 19 3; Host-Specific... Broomrapes 711 Dwarf Mistletoes of Conifers 712 True or Leafy Mistletoes 715 Invasive Climbing Plants Old World Climbing Fern Kudzu Vine 717 716 717 Parasitic Green Algae 719 Cephaleuros 719 Plant