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.

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.

Plant resistance to pathogens is one of the most important strategies of disease control. Knowledge of resistance mechanisms, and of how to exploit them, has made a significant contribution to agricultural productivity. However, the continuous evolution of new variants of pathogen, ana additional control problems posed by new crops and agricultural methods, creates a need for a corresponding increase in our understanding of resistance and ability to utilize it. The study of resistance mechanisms also has attractions from a purely academic point of view. First there is the breadth of the problem, which can be approached at the genetical, molecular, cellular, whole plant or population lev~ls. Often there is the possibility of productive exchange of ideas between different disciplines. Then there is the fact that despite recent advances, many of the mechanisms involved have still to be fully elucidated. Finally, and compared with workers in other areas of biology, the student of resistance is twice blessed in having as his subject the interaction of two or more organisms, with the intriguing problems of recognition, specificity and co-evolution which this raises.

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.

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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.

Plants are vulnerable to pathogens including fungi, bacteria, and viruses, which cause critical problems and deficits. Crop protection by plant breeding delivers a promising solution with no obvious effect on human health or the local ecosystem. Crop improvement has been the most powerful approach for producing unique crop cultivars since domestication occurred, making possible the main innovations in feeding the globe and community development. Genome editing is one of the genetic devices that can be implemented, and disease resistance is frequently cited as the most encouraging application of CRISPR/Cas9 technology in agriculture. Nanobiotechnology has harnessed the power of genome editing to develop agricultural crops. Nanosized DNA or RNA nanotechnology approaches could contribute to raising the stability and performance of CRISPR guide RNAs. This book brings together the latest research in these areas. CRISPR and RNAi Systems: Nanobiotechnology Approaches to Plant Breeding and Protection presents a complete understanding of the RNAi and CRISPR/Cas9 techniques for controlling mycotoxins, fighting plant nematodes, and detecting plant pathogens. CRISPR/Cas genome editing enables efficient targeted modification in most crops, thus promising to accelerate crop improvement. CRISPR/Cas9 can be used for management of plant insects, and various plant pathogens. The book is an important reference source for both plant scientists and environmental scientists who want to understand how nano biotechnologically based approaches are being used to create more efficient plant protection and plant breeding systems. Shows how nanotechnology is being used as the basis for new solutions for more efficient plant breeding and plant protection Outlines the major techniques and applications of both CRISPR and RNAi technologies Assesses the major challenges of escalating these technologies on a mass scale