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United States Department of Agriculture

Agricultural Research Service

Title: Molecular Cloning and Nucleotide Sequencing of Two Members of the Rymovirusgenus and the Phylogenetic Relatedness Between the Rymoviruses and Other Potyviruses.

Authors
item Salm, S - RG & FOREST INST-S AFRICA
item Rey, M - UN WITWATERSRAND-S AFRICA
item Robertson, Nancy - FORMER USDA/ARS
item French, Roy
item Rabenstein, F - FED CTR-PL BRDG-GERMANY
item Schubert, J - FED CTR-PL BRDG-GERMANY

Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 17, 1996
Publication Date: N/A

Interpretive Summary: The potyvirus group is the largest, economically most important group of plant viruses. Members of this group can be transmitted by either aphids, fungi, or mites, and they have been divided into subgroups on this basis. To improve our understanding of the relationships among the mite-transmitted potyviruses, we cloned and sequenced the coat protein genes of two cereal viruses, agropyron mosaic virus (AgMV) and hordeum mosaic virus (HoMV). These two viruses are of interest because they are generally regarded as close relatives of wheat streak mosaic virus (WSMV), a serious pathogen of wheat in the USA and elsewhere. AgMV also occurs in wheat in the Central USA but its overall incidence is not known. Our sequence data clearly demonstrate that while AgMV and HoMV are related, both are quite distinct from WSMV. We previously determined that ryegrass mosaic virus (RgMV) was also distinct from WSMV and now show that the mite-transmitted viruses AgMV, HoMV and RgMV are most closely related to potyviruses with aphid vectors. Thus, the placement of mite-transmitted viruses of cereals and other grasses into a single group does not appear to be justified.

Technical Abstract: Complementary DNAs encompassing the coat protein coding regions of agropyron mosaic virus (AgMV) and hordeum mosaic virus (HoMV) were molecularly cloned and sequenced. Amino acid sequence comparisons of the 3'-terminal regions of these and other Rymoviruses indicate that three distinct groups exist. Ryegrass mosaic virus (RgMV) strains form one cluster while AgMV and HoMV form another. Wheat streak mosaic virus (WSMV) and brome streak mosaic virus (BrSMV) show homology to each other but show limited homology with the other Rymoviruses. Further analysis also revealed that RgMV, AgMV and HoMV appear to be more closely related to members of the Potyvirus genus than to WSMV and BrSMV, as has been indicated previously by serological data. Results of this paper suggest that the present classification of viruses such as RgMV, AgMV and HoMV as Rymoviruses should be reconsidered.

Last Modified: 9/3/2014
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