The Effect Mechanism Of Ailanthus Altissima Extract On Rice Stripe Virus (RSV) In Rice Suspension-cultured Cells

In recent years,rice strap disease caused by Rice stripe virus (RSV) has broken out in china and caused great decreases of rice yields. For lacking of effective antivirus inhibitor, it is very important to screen effective antivirus inhibitor and find out the resistance mechanism in the process of exploring anti RSV inhibitor.In this study, the suspension-cultured cells system of susceptible variety Rice (Wuyujing-3) that could be infected by RSV has been established. Following polyethyleneglycol (PEG) and swirl surge mediated, For sample, indirect fluorescent antibody test (IFAT) was used in RSV, Intracellular fluorescence signal was assayed by fluorescence invert microscope, The result revealed that the colonization rate of RSV in suspension-cultured cells was 30%-35%; We studied the infection cycle of RSV in Rice suspension-cultured cells by ELISA, The result showed RSV could replicate itself quickly in Rice suspension-cultured cells after inoculation 12h and reached peak after 30h.The virus-cells-antivirus system that be used for screening antivirus inhibitor has been established by suspension-cultured cells system. A few antivirus inhibitors that have been known were studied by the virus-cells-antivirus system, We found that Ailanthus altissima extract could inhibit the accumulation of RSV in Rice suspension-cultured cells detected by ELISA, SDS-PAGE and western-blot. The inhibition rate was 80%-90%; however,when Virus and Ailanthus altissima extract mixed at different times, the Ailanthus altissima extract could not degrade RSV CP directly detected by SDS-PAGE; At the same time, total RNAs were extracted from Rice suspension-cultured cells samples that collected at virus peak time, then blotted onto PVDF membrane, and hybridized to DIG-labeled riboprobes specific of gene coding region of the CP-mRNA and SP-mRNA strands. The analyses of the amount of CP-mRNA and SP-mRNA in infected rice cell collected was detected by Northern blot, whose results showed that the accumulation of CP-mRNA and SP-mRNA could not be effected by Ailanthus altissima extract; But the results Real-Time PCR showed that Ailanthus altissima extract could decrease the transcriptions of SP-mRNA in Rice suspension-cultured cells, but the transcriptions of CP-mRNA in Rice suspension-cultured cells was less. By determining the activity of the defendant enzymes including POD, PPO, PAL involved in the interaction between virus and host, it was found that Ailanthus altissima extract could increase defendant enzymes and induce resistance to RSV in the host to some extent, increase inhibitory activity of host against virus infection and reduce the damage caused by virus infection to host cells.The effect mechanism of Ailanthus altissima extract on RSV may be that: Ailanthus altissima extract could not degrade RSV protein directly, but interdict the expression process of virus-mRNA by increasing defendant enzymes. so that the protein of virus in Rice suspension-cultured cells was decreased.