| Most plant viruses are RNA viruses. Double stranded RNA (dsRNA) occurs during the replication of plant viruses. These dsRNAs are corresponding to genome of viruses and subviral agents. Consequently infected tissues contain virus-specific dsRNAs. Since healthy plants produces little or no dsRNA, purification of dsRNA is useful for diagnosis. Cucumber mosaic virus (CMV) is a type of tripartite positive stranded RNA virus. Due to its broad host ranges, heavy damage and easy inoculation, CMV has been utilized as a model species for studying RNA viruses. In this work, optimized conditions for dsRNA extraction were investigated seperately. Then the temporal changes of CMV-dsRNAs were studied by extracting dsRNA analysis from host plants inoculated with CMV. Since Satellite RNA (SatRNA) possesses the character of high copy, we prepared high quantities of dsRNA by extracting and purifying of Sat-dsRNA from CMV-infected host plants. Then, the prepared Sat-dsRNA was injected into rabbits for preparation of antibody to dsRNA. Our results are showed as follows:Based on the characteristic of that CMV replicates rapidly and accumulates in high amount in Nicotiana, the dsRNA extraction condition was optimized as the following. The optimized concentration of ethanol was set at 17% during the CF-11 absorption treatments; The growing condition of plant would have effect on the dsRNA extraction result, for example flourishing and infant plants were more suitable for yielding dsRNA; DsRNA extracted from plant about two weeks after inoculation given the best result, we could harvest about 2.5 microgram of Sat-dsRNA from 5 grams CMV-infected plant tissues. Instead of cellulose column, a small-scale adsorbing procedure in 1.5 milliliters microfuge tube by the method of centrifuge can be completed in Ihr with a contented result.Sat-RNA of CMV is a subviral agent, which depends on its helper virus to replicate and cell to cell diffuse. Under constant temperature and light condition, two CMV isolates, CYi, associated with a Sat-RNA and CFq, being free of Sat-RNA, were inoculatedseparately onto three systemic hosts. The contents of each part dsRNA and the effect of Sat-RNA on its help virus were analyzed in different time. Results showed that the amounts of all three CMV genomic dsRNAs were similar to each other at 8d post inoculation; There after, RNA3-dsRNA tended to increase, but the others decreased. The amount of Sat-dsRNA of CYi was always higher than CMV genomic dsRNAs, the relative dsRNA content of Sat-RNA over RNA3 in host was in-order as Cucurbit pepo>Nicotiana glutinosa >Nicandra physalodes. The above results indicated that C. pepo is a better host for supporting Sat-RNA rather than genomic CMV. Of the two isolates, the ratio of the relative dsRNA amount of RNA3 over RNA1 in CYi was higher than that in CFq. The above phenomenon demonstrates that the dsRNA amounts of both isolates were obviously influenced by the hosts, and farther more, each part of CMV genomic RNA was influenced with temporal changes.Large amounts of Sat-dsRNA were prepared by extracting dsRNA from host plants inoculated with CYi. Sat-dsRNA was conjugated with Bovine serum albumen, and then wrapped in liposome. The mixture was injected into the healthy rabbit's lymph node for producing interested antibody. Electrophoresis graph showed that formaldehyde could conjugate the dsRNA with BSA. Immunoelectrophoresis showed that there were precipitate lines formed by the obtained antiserum with Sat-dsRNA, and CMV-dsRNA. However, it appeared that the antiserum had cross-reaction with dsDNA. Therefore, it could be concluded that the non-specificity of this antiserum induced by dsRNA antigen had little value for application.
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