UBC Theses and Dissertations
Pseudorecombinants of cherry leaf roll virus Haber, Stephen Michael
Cherry leaf roll virus, as a nepovirus with a bipartite genome, can be genetically analysed by comparing the properties of distinct 'parental' strains and the pseudorecombinant isolates generated from them. In the present work, the elderberry (E) and rhubarb (R) strains were each purified and separated into their middle (M) and bottom (B) components by sucrose gradient centrifugation followed by near-equilibrium banding in cesium chloride. RNA was extracted from the separated components by treatment with a dissociation buffer followed by sucrose gradient centrifugation. Extracted M-RNA of E-strain and B-RNA of R-strain were mixed and inoculated to a series of test plants as were M-RNA of R-strain and B-RNA of E-strain. New local lesion types in Nicotiana clevelandii induced by these heterologous RNA combinations were passaged three times through local lesions on N. clevelandii in order to generate pure pseudorecombinant stocks. M-RNA determined serological specificity, the distribution of virus particle components, systemic symptoms in N. clevelandii and N. tabacum cvs. Samsun and Xanthi as well as the local and systemic symptoms in Chenopodium amaranticolor and C. quinoa. B-RNA determined the ability to induce systemic symptoms in Gomphrena globosa and the type of local lesion in N. clevelandii. When the procedure used for originally generating the pseudorecombinants from the parental strains was applied to the pseudorecombinant isolates themselves, isolates were obtained in the predicted manner that were identical to the original parental E- and R-strains.
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