Overview of potyviruses and taxonomy.- The general properties of potyviruses.- Application of genome sequence information in potyvirus taxonomy:an overview.- Inclusion bodies.- Potyviruses, chaos or order?.- What is a virus?.- Serology and antigenic relationships.- Serology of potyviruses: current problems and some solutions.- Polyclonal reference antisera may be useful for the differentiation of potyvirus species.- Proteolytic cleavage of the N-terminal region of potyvirus coat protein and its relation to host recovery and vector transmission.- Some unusual serological reactions among potyviruses.- Potyviruses, monoclonal antibodies, and antigenic sites.- Serological relationships involving poty viral non-structural proteins.- Potyvirus serology, sequences and biology.- Coat protein phylogeny and systematics of potyviruses.- Virus biology and variation.- Importance of host ranges and other biological properties for the taxonomy of plant viruses.- Clustering Potyviridae species on the basis of four major traits.- Specific infectivity and host resistance have predicated poty viral and pathotype nomenclature but relate less to taxonomy.- Sources of resistance to viruses in the Potyviridae.- Potential for using transgenic plants as a tool for virus taxonomy.- A potyvirus in nature: indistinct populations.- Potyvirus taxonomy: potyviruses that affect solanaceous crops.- Biological variants of tobacco etch virus that induce morphologically distinct nuclear inclusions.- Biological variability of potyviruses, an example: zucchini yellow mosaic virus.- Designation of potyvirus genera: a question of perspective and timing.- Fungal transmission of a potyvirus: uredospores of Puccinia sorghi transmit maize dwarf mosaic virus.- The usefulness of aphid transmission as a taxonomie criterion for potyviruses.- Genome and sequence relationships.- Viruses of the Potyviridae with non-aphid vectors.- Potyviridae: genus Rymovirus.- How important is genome division as a taxonomie criterion in plant virus classification?.- Sequence data as the major criterion for potyvirus classification.- The recombinative nature of potyviruses: implications for setting up true phylogenetic taxonomy.- Virus relationships.- Nomenclature and relationships of some Brazilian leguminous potyviruses related to bean common mosaic and/or passionfruit woodiness viruses.- Ecology and taxonomy of some European potyviruses.- Relationships among iris severe mosaic virus (ISMV) isolates.- Virus relationships - PVY subgroup.- A comparison of pepper mottle virus with potato virus Y and evidence for their distinction.- Is pepper mottle virus a strain of potato virus Y?.- Evidence that pepper mottle virus and potato virus Y are distinct viruses: analyses of the coat protein and 3? untranslated sequence of a California isolate of pepper mottle virus.- Virus relationships - SCMV subgroup.- A viewpoint on the taxonomy of potyviruses infecting sugarcane, maize, and sorghum.- Differentiation of the four viruses of the sugarcane mosaic virus subgroup based on cytopathology.- Present status of the sugarcane mosaic subgroup of potyviruses.- Virus relationships - BYMV subgroup.- Bean yellow mosaic virus subgroup; search for the group specific sequences in the 3? terminal region of the genome.- Virus relationships - BCMV subgroup.- A proposal for a bean common mosaic subgroup of.- Serological and biological relationships among viruses in the bean common mosaic virus subgroup.- Strains of bean common mosaic virus consist of at least two distinct potyviruses.- Serotype A and B strains of bean common mosaic virus are two distinct potyviruses.- Summary.- A summary of potyvirus taxonomy and definitions.

A number of economically important diseases are caused by potyviruses, the largest group of plant viruses. Many of these diseases are distributed worldwide. The development of effective control strategies against viruses is dependent on the availability of reliable methods of identification and detection. To date this has not seemed possible for the potyvirus group, because of its size, complexity, and immense variation. This book brings together the collaborative efforts of exports in the field. It summarizes characteristics of potyviruses which relate to their taxonomy and points to areas which require consideration before an international consensus can be reached. Main topics dealt with in detail are: serological relationships, nucleic acid sequence information, biological properties, and specific problems with several virus subgroups or pairs of viruses.