Kasschau K D, Carrington J C
Institute of Biological Chemistry, Washington State University, Pullman 99164-6340, USA.
Cell. 1998 Nov 13;95(4):461-70. doi: 10.1016/s0092-8674(00)81614-1.
Posttranscriptional gene silencing (PTGS) in plants inactivates some aberrant or highly expressed RNAs in a sequence-specific manner in the cytoplasm. A silencing mechanism similar to PTGS appears to function as an adaptive antiviral response. We demonstrate that the P1/HC-Pro polyprotein encoded by tobacco etch virus functions as a suppressor of PTGS. A locus comprised of a highly expressed beta-glucuronidase (GUS) transgene was shown to exhibit PTGS. Genetic crosses and segregation analyses revealed that a P1/ HC-Pro transgene suppressed PTGS of the GUS sequence. Nuclear transcription assays indicated that the silencing suppression activity of P1/HC-Pro was at the posttranscriptional level. These data reveal that plant viruses can condition enhanced susceptibility within a host through interdiction of a potent defense response.
植物中的转录后基因沉默（PTGS）在细胞质中以序列特异性方式使一些异常或高表达的RNA失活。一种类似于PTGS的沉默机制似乎作为一种适应性抗病毒反应发挥作用。我们证明烟草蚀纹病毒编码的P1/HC-Pro多聚蛋白作为PTGS的抑制子发挥作用。一个由高表达的β-葡萄糖醛酸酶（GUS）转基因组成的位点被证明表现出PTGS。遗传杂交和分离分析表明，P1/HC-Pro转基因抑制了GUS序列的PTGS。细胞核转录分析表明，P1/HC-Pro的沉默抑制活性处于转录后水平。这些数据揭示了植物病毒可以通过阻断一种有效的防御反应来使宿主内的易感性增强。
