The Plant Viruses

Plant viruses cause many of the most important diseases threatening crops worldwide. Over the last quarter of a century, an increasing number of plant viruses have emerged in various parts of the world, especially in the tropics and subtropics. As is generally observed for plant viruses, most of the emerging viruses are transmitted horizontally by biological vectors, mainly insects. Reverse genetics using infectious clones--available for many plant viruses--has been used for identification of viral determinants involved in virus-host and virus-vector interactions. Although many studies have identified a number of factors involved in disease development and transmission, the precise mechanisms are unknown for most of the virus-plant-vector combinations. In most cases, the diverse outcomes resulting from virus-virus interactions are poorly understood. Although significant advances have been made towards understand the mechanisms involved in plant resistance to viruses, we are far from being able to apply this knowledge to protect cultivated plants from the all viral threats.The aim of this Special Issue was to provide a platform for researchers interested in plant virology to share their recent results. To achieve this, we invited the plant virology community to submit research articles, short communications and reviews related to the various aspects of plant virology: ecology, virus-plant host interactions, virus-vector interactions, virus-virus interactions, and control strategies. This issue contains some of the best current research in plant virology.

The seminal text Plant Virology is now in its fifth edition. It has been 10 years since the publication of the fourth edition, during which there has been an explosion of conceptual and factual advances. The fifth edition of Plant Virology updates and revises many details of the previous edition while retaining the important earlier results that constitute the field's conceptual foundation. Revamped art, along with fully updated references and increased focus on molecular biology, transgenic resistance, aphid transmission, and new, cutting-edge topics, bring the volume up to date and maintain its value as an essential reference for researchers and students in the field. Thumbnail sketches of each genera and family groups Genome maps of all genera for which they are known Genetic engineered resistance strategies for virus disease control Latest understanding of virus interactions with plants, including gene silencing Interactions between viruses and insect, fungal, and nematode vectors Contains over 300 full-color illustrations

Plant virus and sub-viral pathogens pose severe constraints to the production of wide range of economically important crops worldwide. The crops raised both through true seed and vegetative propagated materials are affected with number of virus and virus-like diseases. The virus may enter into plants through seed planting materials or by vectors. Once the virus is in the field, it multiplies and spreads following definite patterns depending upon the nature of the vector and agro-meteorological conditions. Disease free crops and plants are great economic and social importance in feeding the world's population. Detection of virus and sub-viral agents at initial stages of infection is critical to reduce economic losses. For nearly two decades, ELISA and its variants played a major role in large scale virus testing and also in the production of virus-free planting materials.

Pathogens transmitted among humans, animals, or plants by insects and arthropod vectors have been responsible for significant morbidity and mortality throughout recorded history. Such vector-borne diseases â€" including malaria, dengue, yellow fever, and plague â€" together accounted for more human disease and death in the 17th through early 20th centuries than all other causes combined. Over the past three decades, previously controlled vector-borne diseases have resurged or reemerged in new geographic locations, and several newly identified pathogens and vectors have triggered disease outbreaks in plants and animals, including humans. Domestic and international capabilities to detect, identify, and effectively respond to vector-borne diseases are limited. Few vaccines have been developed against vector-borne pathogens. At the same time, drug resistance has developed in vector-borne pathogens while their vectors are increasingly resistant to insecticide controls. Furthermore, the ranks of scientists trained to conduct research in key fields including medical entomology, vector ecology, and tropical medicine have dwindled, threatening prospects for addressing vector-borne diseases now and in the future. In June 2007, as these circumstances became alarmingly apparent, the Forum on Microbial Threats hosted a workshop to explore the dynamic relationships among host, pathogen(s), vector(s), and ecosystems that characterize vector-borne diseases. Revisiting this topic in September 2014, the Forum organized a workshop to examine trends and patterns in the incidence and prevalence of vector-borne diseases in an increasingly interconnected and ecologically disturbed world, as well as recent developments to meet these dynamic threats. Participants examined the emergence and global movement of vector-borne diseases, research priorities for understanding their biology and ecology, and global preparedness for and progress toward their prevention, control, and mitigation. This report summarizes the presentations and discussions from the workshop.

The Encyclopedia of Plant Viruses and Viroids provides an up-to-date information on the viruses and viroids infecting all types of cultivated and weed plants at global level; and is unique among plant virology texts as it is organized alphabetically by the genus name of the host plant infected. It allows the reader to readily determine all of the different viruses currently reported naturally infecting the plant genus and species. Information is provided for each virus and viroids on common synonyms, current taxonomic status, geographical distribution, symptoms induced, other known hosts, means of transmission and properties of both the virus particles and the genome. Where ever the same virus is known to infect multiple hosts, host-specific information, biological properties and genome characters are presented under each host affected. The index can be utilized to identify other crops infected by the same virus, showing which other crops might be at risk of infection in the event of introduction of a virus that has not previously reported in an area, or which might serve as potential virus reservoirs for infection of more sensitive or economically important crops than the host in which it is initially identified. The taxonomy and nomenclature of the viruses and viroids are followed based on the current guidelines of the 10th ICTV Report, covering up to 2018 and also about many new viruses and viroids that have been reported but not yet recognized as species by ICTV, have been included in this Encyclopedia. The uniqueness of this Encyclopedia is that all the known viruses and viroids affecting more than 1010 plant species at global level are described and the plant species are arranged in alphabetical order of the scientific name of the plant along the relevant information on 1518 viruses and viroids and is the ready-reckoner of the global plant species and their viruses and viroids for students, scientists, teachers of Plant Pathology& Virology; and also for the crop protection professionals, agricultural policymakers, seed companies and quarantine agencies.

Handbook of Plant Virus Diseases presents basic information about viral-caused and viral-like diseases in many cultivated crops. The editors, internationally known plant pathologists, provide authoritative descriptive symptomatic signatures of virus diseases, to aid in the diagnosis and possible control of viruses. This handbook organizes cultivated plants into groups according to their final destinations and uses after harvest-a useful grouping system that indicates that some diseases, their resultant epidemiology, and control measures are characteristic within different groups.

This volume of the series The Plant Viruses is devoted to viruses with rod-shaped particles belonging to the following four groups: the toba moviruses (named after tobacco mosaic virus), the tobraviruses (after to bacco rattle), the hordeiviruses (after the latin hordeum in honor of the type member barley stripe mosaic virus), and the not yet officially rec ognized furoviruses (fungus-transmitted rod-shaped viruses, Shirako and Brakke, 1984). At present these clusters of plant viruses are called groups instead of genera or families as is customary in other areas of virology. This pe culiarity of plant viral taxonomy (Matthews, 1982) is due to the fact that the current Plant Virus Subcommittee of the International Committee of Taxonomy of Viruses is deeply split on what to call the categories or ranks used in virus classification. Some plant virologists believe that the species concept cannot be applied to viruses because this concept, according to them, necessarily involves sexual reproduction and genetic isolation (Milne, 1984; Murant, 1985). This belief no doubt stems from the fact that these authors restrict the use of the term species to biological species. According to them, a collection of similar viral isolates and strains does constitute an individ ual virus, i. e. , it is a taxonomy entity separate from other individual viruses.

In the sixth edition of Plant Viruses, each section has been brought up to date and some additions made. A short account is given of a new technique, the protoplast-culture of plant viruses. The omission in the fifth edition of the Mycoplasma-like organisms has been criticized on the grounds of the close simi larity of symptom expression and techniques of study between Mycoplasmas and plant viruses. To meet this criticism Chapter 16, which gives a brief account of these organisms, is included. Some of the plates have been changed and new ones added. Grateful acknowledgment is due to Dr Aaron KIug F.R.S. and his colleagues, to Drs D. A. Govier, Basil Kassanis F.R.S. and Karl Maramorsch for permission to use their recent work. Acknowledgement is also due to several friends who have supplied prints of illustrations from their published work; credit has been given to authors in the illustration legends. Mr Denis C. Ingram, editor to Chapman and Hall, has been most helpful and co-operative throughout.