Shams-Bakhsh Masoud, Canto Tomas, Palukaitis Peter
Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK.
Virus Res. 2007 Dec;130(1-2):103-9. doi: 10.1016/j.virusres.2007.05.023. Epub 2007 Jul 6.
The effects of transgenic expression of the potato virus Y (PVY) HCPro silencing suppressor in tobacco were examined on infection by several viruses. Infection by tobacco mosaic virus (TMV) was reduced at 25 degrees C, but not at 33 degrees C. By contrast, systemic infection at 33 degrees C by the TMV expressing green fluorescent protein was promoted by the HCPro. Infection by tobacco rattle virus (TRV) was restricted to local necrotic lesions by the PVY HCPro. However, this resistance was neutralized by expression of the cucumber mosaic virus (CMV) 2b protein from TRV. By contrast, infection by either wild-type CMV or CMV with a deletion of the 2b gene was not affected. Similarly, infection by cauliflower mosaic virus, red clover necrotic mosaic virus (both limited to infection of the inoculated leaves of tobacco) or tomato bushy stunt virus (systemically infecting tobacco) was not altered by the expression of PVY HCPro. Therefore, it appeared that the PVY HCPro was able to induce defense responses at 25 degrees C, but not at 33 degrees C, where it actually neutralized a pre-existing defense response. Moreover, the CMV 2b protein was able to neutralize a defense response activated by HCPro in combination with TRV.
研究了马铃薯Y病毒（PVY）HCPro沉默抑制子在烟草中的转基因表达对几种病毒感染的影响。烟草花叶病毒（TMV）在25℃时感染减少，但在33℃时没有减少。相比之下，HCPro促进了在33℃时表达绿色荧光蛋白的TMV的系统感染。PVY HCPro将烟草脆裂病毒（TRV）的感染限制在局部坏死病变。然而，黄瓜花叶病毒（CMV）2b蛋白从TRV表达后，这种抗性被中和。相比之下，野生型CMV或缺失2b基因的CMV的感染不受影响。同样，花椰菜花叶病毒、红三叶草坏死花叶病毒（两者都仅限于感染烟草的接种叶片）或番茄丛矮病毒（系统感染烟草）的感染也不会因PVY HCPro的表达而改变。因此，似乎PVY HCPro能够在25℃时诱导防御反应，但在33℃时不能，在33℃时它实际上中和了预先存在的防御反应。此外，CMV 2b蛋白能够中和由HCPro与TRV共同激活的防御反应。
