From February 24 -28, 1992 an international symposium on Durability of Disease Resistance was held at the International Agricultural Centre in Wageningen, the Netherlands. The symposium, organized by the Department of Plant Breeding of Wageningen Agricultural University and the Centre for Plant Breeding and Repro duction Research, CPRO-DLO, was part of the DGIS funded programme Durable Resistance in Developing Countries. Without any form of prevention or protection nearly all crops will be seriously or even severely damaged by a range of pathogens. In modern agriculture man has been able to control many if not most pathogens using i) pesticides, ii) phyto sanitary methods such as control of seed and plant material in order to start a crop disease free, iii) agronomic measures such as crop rotation, iv) disease resis tance or combinations of these measures. Over the years the use of pesticides has increased enormously and so did the pro blems associated with pesticide use, such as environmental pollution and building of resistance and tolerance to these pesticides in the pathogens. The use of resis tance too increased strongly over the years and here too problems arose.
Plant diseases and pests are a major constraint to agricultural production despite the various measures used to control them. Chemical control, although often e~~ective, may pose environmental hazards and is relatively expensive, especially in developing countries where it may be completely uneconomic. Control through genetically mediated resistance to diseases and pests, is both cheap and environmentally sa~e and at present most diseases and pests o~ staple ~ood crops are controlled through some form of resistance. One of the basic problems in the use of resistance is its ~re quent lack of durability; very often a type of resistance is used that 'breaks down' after a certain period. The temporary nature of this resistance, due to the development of new strains of pest or pathogen able to overcome it, has seriously hindered the improvement o~ the yield potential of many crops as a continuing effort is needed to replace old cultivars who resistance has failed, with new ones. Following Vanderplank's now classical publications (1963, 1968) which differentiated horizontal and vertical resistance, studies on several host-parasite systems have shown that di~ferent types of resistance can be distinguished genetically and epidemiologically, and on the ability o~ the pests or pathogens to adapt to them. A knowledge of how resistance operates at the population level has also opened up possibilities of 'managing' relatively simple resistance types in such a way that a stable host-pathogen system can be pro duced with a minimum of crop loss.
Human population is escalating at an enormous pace and is estimated to reach 9.7 billion by 2050. As a result, there will be an increase in demand for agricultural production by 60–110% between the years 2005 and 2050 at the global level; the number will be even more drastic in the developing world. Pathogens, animals, and weeds are altogether responsible for between 20 to 40 % of global agricultural productivity decrease. As such, managing disease development in plants continues to be a major strategy to ensure adequate food supply for the world. Accordingly, both the public and private sectors are moving to harness the tools and paradigms that promise resistance against pests and diseases. While the next generation of disease resistance research is progressing, maximum disease resistance traits are expected to be polygenic in nature and controlled by selective genes positioned at putative quantitative trait loci (QTLs). It has also been realized that sources of resistance are generally found in wild relatives or cultivars of lesser agronomic significance. However, introgression of disease resistance traits into commercial crop varieties typically involves many generations of backcrossing to transmit a promising genotype. Molecular marker-assisted breeding (MAB) has been found to facilitate the pre-selection of traits even prior to their expression. To date, researchers have utilized disease resistance genes (R-genes) in different crops including cereals, pulses, and oilseeds and other economically important plants, to improve productivity. Interestingly, comparison of different R genes that empower plants to resist an array of pathogens has led to the realization that the proteins encoded by these genes have numerous features in common. The above observation therefore suggests that plants may have co-evolved signal transduction pathways to adopt resistance against a wide range of divergent pathogens. A better understanding of the molecular mechanisms necessary for pathogen identification and a thorough dissection of the cellular responses to biotic stresses will certainly open new vistas for sustainable crop disease management. This book summarizes the recent advances in molecular and genetic techniques that have been successfully applied to impart disease resistance for plants and crops. It integrates the contributions from plant scientists targeting disease resistance mechanisms using molecular, genetic, and genomic approaches. This collection therefore serves as a reference source for scientists, academicians and post graduate students interested in or are actively engaged in dissecting disease resistance in plants using advanced genetic tools.
This collection reviews advances in the key areas required to achieve durable disease resistance in cereal crops, from advances in understanding pathogen biology/epidemiology and plant pathogen interactions to identifying sources of resistance and advance techniques for breeding new varieties.
Arthropod resistant crops reduce pesticide pollution, alleviate hunger and improve human nutrition. This book reviews new information on environmental advantages of plant resistance, transgenic resistance, molecular bases of resistance, and use of molecular markers to map resistance genes.
New technologies are becoming available for managing glyphosate resistant (GR) weeds and reducing their spread. GR crop technology has revolutionized crop production in the developed world and the benefits are gradually spilling over to the developing world. In order to sustain an effective, environmentally safe herbicide such as glyphosate and the GR crop technology well in to the future, it is imperative that the issue of GR weeds be comprehensively understood. This book provides such an essential, up-to-date source of information on glyphosate resistance for researchers, extension workers, land managers, government personnel, and other decision makers. Provides comprehensive coverage of the intensely studied topic of glyphosate resistant (GR) in crops Details the development of glyphosate resistance and how to detect and manage the problem in crops Helps standardize global approaches to glyphosate resistance Encompasses interdisciplinary approaches in chemistry, weed science, biochemistry, plant physiology, plant biotechnology, genetics, ecology Includes a chapter on economic analysis of GR impact on crops
Studies in the Agricultural and Food Sciences: Plant Breeding for Pest and Disease Resistance presents a critical review of the development of resistant varieties of plant to pests and diseases. It discusses the economic impact of pests and diseases; the methods of controlling these pests and diseases; and the challenges being faced by a plant breeder. Some of the topics covered in the book are the general principles and methods of breeding for resistance; importance of parasite variability to the plant breeder; methods of testing for resistance; requirements for successful inoculation; production of resistant varieties; and economic importance of fungal diseases; and variability in fungal pathogen. Pathogenic fungi and fungal diseases are also covered. The control of fungal diseases by resistant varieties is discussed. An in-depth analysis of diseases in plants is provided. The characteristics of bacteria and bacterial diseases are also presented. A chapter is devoted to epidemiology of diseases associated with mycoplasma-like organisms and rickettsia-like organisms. The book can provide useful information to farmers, botanists, students, and researchers.
In the tradition of Silent Spring, Raoul Robinson's Return to Resistance calls for a revolution. Traditional plant breeding techniques have led us to depend more and more on chemical pesticides to protect ourcrops. Return to Resistance shows gardeners, farmers, and plant breeders how to use a long-neglected technique to create hardy new plant varieties that are naturally resistant to pests and disease. Horizontal resistance breeding has been largely ignored in this century due to the popularity and apparent successes of the Mendelian geneticists. However the colossal, unrecognized failure of m.
There is an increasing need for an understanding of the fundamental processes involved in the mechanisms by which disease resistances are introduced into crop plants. This book provides a wide-ranging coverage of the successes and failures of the classical techniques; it describes the advances towards modern technology and addresses the problems of pathogen variation. Crop plants that are considered include: cereals (wheat, barley, rice), potatoes, vegetables and soft fruits.
Disease Resistance in Plants, Second Edition, looks at genetic, epidemiologic, biochemical, and biometric principles for developing new cultivars possessing genetic resistance to diseases. It examines the nature of disease resistance and resistance genes, and it highlights the importance of stabilizing selection, sugar, biotrophy, and necrotrophy to obtain the greatest possible yields. Organized into 17 chapters, this volume begins with an overview of disease resistance in plants and the ways to develop disease-resistant variants. It then discusses unspecific resistance; the resistance gene paradox; susceptibility and resistance within narrow host taxa; phenotypic variation and gene numbers in host plants; discontinuous variation and cytoplasmic inheritance; and experimental difficulties in partitioning variance. The reader is also introduced to epistasis and the structure of virulence in pathogens; the notion of physiological race; how the pathogen adapts to the host; mutation in the pathogen from avirulence to virulence; horizontal and vertical resistance to disease and its epidemiological effects; and the link between protein polymorphism and vertical resistance. In addition, the book discusses genes for susceptibility in the host versus genes for avirulence (or virulence) in the pathogen; sink-induced loss of resistance; high-sugar disease processes and biotrophy; slow rusting of cereal crops; plant resistance against endemic disease; and the accumulation of resistance genes in heterogeneous host populations. This book will be useful to plant pathologists and plant breeders.
