This book provides comprehensive knowledge of the methods of detection and identification of phyllosphere microbial pathogens and the management of different kinds of diseases caused by them in various crops. Interactions between pathogens and host plants result in the induction of defense responses expressed via molecular signals, from initiation of infection to systemic progression of pathogen invasion in susceptible plants and contrasting signals in resistant plants, leading to inhibition of pathogen development through activation of preinfectional and postinfectional defense responses. These are critically discussed. The author describes the intricate and complex competitive activities of the pathogens and host plants in a molecular warfare that the host plant must win to break the link in the pathogens' life cycle, allowing the development of disease management strategies based on the principles of exclusion, eradication, and immunization. Integration of strategies concerning the development of cultivars resistant to pathogens through breeding and biotechnological techniques, application of biotic and abiotic inducers of resistance to pathogens, and use of disease-free seeds and propagules that are complementary to each other along with effective cultural practices are emphasized. This book presents information gathered through an extensive literature search to help researchers and graduate students in agricultural sciences identify research gaps and successfully complete their research projects.
Investigations on various aspects of plant-pathogen interactions have the ultimate aim of providing information that may be useful for the development of effective crop disease management systems. Molecular techniques have accelerated the formulation of short- and long-term strategies of disease management. Exclusion and eradication of plant pathogens by rapid and precise detection and identification of microbial pathogens in symptomatic and asymptomatic plants and planting materials by employing molecular methods has been practiced extensively by quarantines and certification programs with a decisive advantage. Identification of sources of resistance genes, cloning and characterization of desired resistance genes and incorporation of resistance gene(s) into cultivars and transformation of plants with selected gene(s) have been successfully performed by applying appropriate molecular techniques. Induction of resistance in susceptible cultivars by using biotic and abiotic inducers of resistance is a practical proposition for several crops whose resistance levels could not be improved by breeding or transformation procedures. The risks of emergence of pathogen strains less sensitive or resistant to chemicals have been reduced appreciably by rapid identification of resistant strains and monitoring the occurrence of such strains in different geographical locations.
This edited book elucidates the evolution of plant virus, genomic structure, diversity, plant-virus interaction, subcellular movement etc. The book reviews the biological machineries which allow the emergence of virus populations adapted by plant. The main objective of this book is the demonstration of a clear synergistic effect of plant viruses, an effect that was unexpectedly as important as applied alone. Ornamental plants are very popular and economically important worldwide. The international market of ornamentals is constantly expanding. Viruses and viroids can significantly reduce both decorative value and quality of propagated material of ornamentals. Due to the wide range of ornamental plant species and cultivars and their wide geographical distribution, the diversity of viruses that infect them is also high. The new emerging viruses are the causal agent for the economic loss of many important ornamental plants. Therefore, this book also adds value to current knowledge of virus stress response in ornamental plants and will provide the groundwork necessary for building future strategies for product enhancement. This book is of interest to teachers, researchers, capacity builders and policymakers. It can serve as additional reading material for undergraduate and graduate students of virology, agriculture and plant sciences.
Plant viruses grouped within this family have remarkable properties, prominent among which is their genomic size: Citrus tristeza virus (CTV) has the largest (19.3 kb) genome reported for a plant monopartite single-stranded RNA (+) virus. Virions are filamentous and typically flexuous particles, approximately 12 nm in diameter and 650 to 2000 nm in length, with a unique bipolar (“rattlesnake”) morphology: the major coat protein (CP) encapsidates most of the genomic RNA, with a minor CP (CPm) coating a small 5’-terminal fragment (virion tail) and other viral-encoded proteins being also incorporated to this tail. The genome is monopartite (genus Closterovirus, type member Beet yellows virus, and genus Ampelovirus, type member Grapevine leafroll-associated virus 3) or bipartite (genus Crinivirus, type member Lettuce infectious yellows virus, with at least one example of tripartite genome). The genomic RNA (or RNA1 in criniviruses) directs translation of the two 5’-proximal ORFs (via a peculiar ribosomal frameshift mechanism and proteolytic processing) that encode replication-related components, with the 3’-proximal ORFs encoding proteins expressed from 3’-coterminal subgenomic RNAs. A genomic signature of members of the family Closteroviridae is the presence of a five-gene block of proteins involved in virion assembly and movement that, in addition to the CP and CPm, includes a small transmembrane protein, a homologue of the HSP70 class of heat-shock proteins and a diverged CP. Members of this family encode suppressors of RNA silencing differing in number (up to three in CTV), and in mode of action: intracellular, intercellular, or both. In this same context Sweet potato chlorotic stunt virus codes for a singular suppressor: an RNase III that catalyzes cleavage of the small interfering RNAs mediating RNA silencing. Host range is usually narrow and, in order to expand it, some member(s) of the family, illustrated by the case of CTV, have evolved by acquiring multiple non-conserved genes. Virion accumulation is restricted to the phloem, with aphids, mealybugs and whiteflies (depending on the genus) operating as natural vectors. Disease symptoms may be expressed in leaves, fruits and trunk of the woody hosts. Natural Plant viruses grouped within this family have remarkable properties, prominent among which is their genomic size: Citrus tristeza virus (CTV) has the largest (19.3 kb) genome reported for a plant monopartite single-stranded RNA (+) virus. Virions are filamentous and typically flexuous particles, approximately 12 nm in diameter and 650 to 2000 nm in length, with a unique bipolar (“rattlesnake”) morphology: the major coat protein (CP) encapsidates most of the genomic RNA, with a minor CP (CPm) coating a small 5’-terminal fragment (virion tail) and other viral-encoded proteins being also incorporated to this tail. The genome is monopartite (genus Closterovirus, type member Beet yellows virus, and genus Ampelovirus, type member Grapevine leafroll-associated virus 3) or bipartite (genus Crinivirus, type member Lettuce infectious yellows virus, with at least one example of tripartite genome). The genomic RNA (or RNA1 in criniviruses) directs translation of the two 5’-proximal ORFs (via a peculiar ribosomal frameshift mechanism and proteolytic processing) that encode replication-related components, with the 3’-proximal ORFs encoding proteins expressed from 3’-coterminal subgenomic RNAs. A genomic signature of members of the family Closteroviridae is the presence of a five-gene block of proteins involved in virion assembly and movement that, in addition to the CP and CPm, includes a small transmembrane protein, a homologue of the HSP70 class of heat-shock proteins and a diverged CP. Members of this family encode suppressors of RNA silencing differing in number (up to three in CTV), and in mode of action: intracellular, intercellular, or both. In this same context Sweet potato chlorotic stunt virus codes for a singular suppresso.
Biological disease management tactics have emerged as potential alternative to chemical application for containing crop diseases. Biotic and abiotic biological control agents (BCAs) have been demonstrated to be effective against diseases caused by microbial plant pathogens. Combination of biotic and abiotic agents leads to synergism and consequent improvement in the effectiveness of disease control. It is essential to assay the biocontrol potential of all isolates/species of fungal, bacterial and viral biocontrol agents by different techniques in vitro and under greenhouse and field conditions and to precisely identify and differentiate the most effective isolates from less effective ones by employing biological, immunological and nucleic acid-based assays.
Encyclopedia of Virology, Fourth Edition, Five Volume Set builds on the solid foundation laid by the previous editions, expanding its reach with new and timely topics. In five volumes, the work provides comprehensive coverage of the whole virosphere, making this a unique resource. Content explores viruses present in the environment and the pathogenic viruses of humans, animals, plants and microorganisms. Key areas and concepts concerning virus classification, structure, epidemiology, pathogenesis, diagnosis, treatment and prevention are discussed, guiding the reader through chapters that are presented at an accessible level, and include further readings for those needing more specific information. More than ever now, with the Covid19 pandemic, we are seeing the huge impact viruses have on our life and society. This encyclopedia is a must-have resource for scientists and practitioners, and a great source of information for the wider public. Offers students and researchers a one-stop shop for information on virology not easily available elsewhere Fills a critical gap of information in a field that has seen significant progress in recent years Authored and edited by recognized experts in the field, with a range of different expertise, thus ensuring a high-quality standard
For many years the use of chemical agents such as pesticides and herbicides has been effective in controlling the many varieties of pests that infest both agricultural crops and backyard gardens. However, these pests are gradually becoming resistant to these agents, because the agents themselves are acting as selective factors making the pests better and better able to resist and persist. As a result, the use of biological controlling agents is increasing. This book is a comprehensive and authoritative handbook of biological control.
