Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Comparison of rymoviruses and partial characterization of a potyvirus infecting smilograss in Morocco
Abstract
Capsid proteins, cylindrical inclusions and nucleotide sequences of the 3$\sp\prime$ untranslated region of the RNA of 5 rymoviruses were compared. Their serological relationships using western blot technique were re-examined. All the studied rymoviruses have a large capsid protein and varying amounts of smaller proteins. The presence of a large capsid protein appears to be a fundamental characteristic and is taxonomically significant. Their cylindrical inclusions have similar molecular weights. Western blots with polyclonal antibodies revealed two distinct serotypes. One consisted of wheat streak mosaic virus (WSMV) and oat necrotic mottle virus (ONMV) and the other contained agropyron mosaic virus (AgMV), hordeum mosaic virus (HorMV) and ryegrass mosaic virus (RMV). Though, antiserum to RMV did not react to AgMV and HorMV. Rymovirus RNAs were reverse transcribed and the resulting DNAs were amplified by the polymerase chain reaction with degenerate oligonucleotide primers. The 3$\sp\prime$ untranslated regions of ONMV and RMV have been cloned and sequenced. The 3$\sp\prime$ non-coding region of ONMV showed little homology to WSMV (50-56% homology). The RMV 3$\sp\prime$ terminal sequence differs from that of AgMV (34% identity) and that of HorMV (33% identity). The deduced amino acid sequence from the 5$\sp\prime$ end of a clone of RMV-Canada was 48% identical to a region of the nuclear inclusion (Nlb) cistron of tobacco etch virus. All the rymoviruses studied appear to be distinct. A virus infecting smilograss plants in Morocco was included in this study because it was a suspected rymovirus. Flexuous rod shaped particles typical of other known grass viruses were associated with smilograss plants collected in the field or manually inoculated. This virus had a capsid protein of 35.4 Kilodaltons (Kd) and induced cylindrical inclusion protein of 66.3 Kd. Western blot analysis of its capsid proteins showed that it was unrelated to rymoviruses or other sorghum infecting viruses. Degenerate oligonucleotide primers complementary to conserved genomic sequences shared by other viruses in the Potyviridae family were used to generate a 3$\sp\prime$ terminal cDNA of c 2,000 nucleotides. The nucleotide sequence of the two ends of this cDNA revealed a poly (A) tract at its 3$\sp\prime$ end. The deduced amino acids from its 5$\sp\prime$ end shared 50% identity with hordeum mosaic virus and 60% homology with tobacco etch virus nuclear inclusion (Nlb) cistron. Therefore, the virus isolated from smilograss in Morocco is a new member of the Potyviridae family and provisionally designated smilograss mosaic virus (SmMV).
Subject Area
Plant pathology|Molecular biology
Recommended Citation
Remah, Abdallah, "Comparison of rymoviruses and partial characterization of a potyvirus infecting smilograss in Morocco" (1993). ETD collection for University of Nebraska-Lincoln. AAI9406090.
https://digitalcommons.unl.edu/dissertations/AAI9406090