Potyviridae , a proposed family of plant viruses
- PDF / 322,973 Bytes
- 3 Pages / 562 x 774 pts Page_size
- 48 Downloads / 201 Views
Potyviridae, a proposed family of plant viruses The potyvirus group was one of the six plant virus groups, defined largely on the basis of particle length [1]. At that time, the group contained 16 serologically related viruses with flexuous particles 730-760 nm in length. From the Fourth Report of the International Committee on Taxonomy of Viruses [11], a paraphrase of the potyvirus group description might be: viruses with flexuous filamentous particles 680-900nm long and 11 nm wide having one coat polypeptide and one molecule of linear positive-sense ssRNA which characteristically induces pinwheel inclusions in the cytoplasm of infected plants. The Fourth Report listed 48 aphid-borne viruses as definitive members of the potyvirus group. Possible members of the group were subdivided into aphid-borne (56 viruses), fungal-borne (5 viruses), mite-borne (5 viruses), and whitefly-borne (1 virus) categories. In the manuscript for the Figth Report of the ICTV (collated for the VIIIth International Congress of Virology, August 1990, Berlin, for publication in the Archives of Virology) members of this working group listed 73 definitive members, and possible members were separated into aphid-borne (74 viruses), fungal-borne (5 viruses), mite-borne (7 viruses), and whitefly-borne (1 virus) categories. In 1984 the editors of the CMI/AAB Descriptions of Plant Viruses tentatively subdivided the potyvirus group into four subgroups based on vectors. This sub-grouping was for convenience because the group had grown so large and because it seemed the most logical way to subdivide the group (A. F. Murant, pers. comm.). Although the ICTV listed the fungal-, mite-, and whitefly-borne categories as possible members, others felt that these viruses should be excluded from the potyvirus group until more information was available on the affinities of these viruses to the aphid-borne members [3, 4]. In the 1988 Set of Descriptions of Plant Viruses, the barley yellow mosaic virus group, which included the fungal-borne viruses, was listed as a separate group independent from the potyvirus group. This group was established due to the findings that the fungal-borne possible members of the potyvirus group have a bimodal particle distribution and a bipartite genome [5, 9]. When the nucleotide sequence of the capsid protein gene of barley yellow mosaic virus was obtained, differences and similarities with aphid-borne potyviruses were found [6-8]. The capsid protein gene is located on the Y-proximal region of RNA 1 and codes for a 297 amino acid protein with an Mr of 32,334; the capsid protein is produced by proteolytic processing; the N- and C-terminal regions of the capsid protein are removed by mild proteolysis of intact particles; and the capsid protein had only small blocks of amino acids homologous to those of potyviruses in other vector groups. These results, together with the bipartite genome, their transmission by a fungus, and the absence of a serological relationship with aphid-borne potyviruses [14] ted to the submission of a proposal fo
Data Loading...
