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Cross protection against the watermelon strain of Papaya ringspot virus through modification of viral RNA silencing suppressor

Huang, Xian-De, Fang, Le, Gu, Qin-Sheng, Tian, Yan-Ping, Geng, Chao, Li, Xiang-Dong
Virus research 2019 v.265 pp. 166-171
Citrullus lanatus, Cucumis melo, Cucumis sativus, Cucurbita pepo, Papaya ringspot virus, RNA interference, cross immunity, financial economics, fluorescence, genes, green fluorescent protein, leaves, mutants, proteinases, site-directed mutagenesis, viruses, watermelons
Papaya ringspot virus watermelon strain (PRSV-W) causes huge economic losses to cucurbits production. Here, we constructed an infectious clone of PRSV-W, pCamPRSV-W, which can induce similar symptoms and accumulate to same levels as wild type virus in plants of Cucurbita pepo, Cucumis melo, Citrullus lanatus and Cucumis sativus. The green fluorescence protein gene gfp was cloned into pCamPRSV-W to produce pCamPRSV-W-GFP, which produced strong green fluorescence in systemic leaves of inoculated Cucurbita pepo, Cucumis melo, Citrullus lanatus and Cucumis sativus plants, indicating that pCamPRSV-W can be used to express foreign genes. Ten mutants of PRSV-W, obtained by site-directed mutagenesis in the RNA silencing suppressor helper-component proteinase encoding region, produced dramatically attenuated symptoms in plants of Cucumis melo. The Cucumis melo plants pre-infected with mutants K125D and G317 K showed effective protection against the challenge inoculation of wild type PRSV-W. The attenuated mutants generated in this study will be helpful for the eco-friendly control of PRSV-W.