Ruiz MT, Voinnet O, Baulcombe DC
Sainsbury Laboratory, John Innes Centre, Colney, Norwich NR4 7UH, United Kingdom.
Plant Cell. 1998 Jun;10(6):937-46. doi: 10.1105/tpc.10.6.937.
The phytoene desaturase (PDS) gene of Nicotiana benthamiana was silenced in plants infected with potato virus X (PVX) vectors carrying PDS inserts, and a green fluorescent protein (GFP) transgene was silenced in plants infected with PVX-GFP. This virus-induced gene silencing (VIGS) is post-transcriptional and cytoplasmic because it is targeted against exons rather than introns of PDS RNA and against viral RNAs. Although PDS and GFP RNAs are most likely targeted through the same mechanism, the VIGS phenotypes differed in two respects. PDS mRNA was targeted by VIGS in all green tissue of the PVX-PDS-infected plant, whereas PVX-PDS was not affected. In contrast, VIGS of the GFP was targeted against PVX-GFP. Initially, VIGS of the GFP was initiated in all green tissues, as occurred with PDS VIGS. However, after 30 days of infection, the GFP VIGS was no longer initiated in newly emerging leaves, although it was maintained in tissue in which it had already been initiated. Based on these analyses, we propose a model for VIGS in which the initiation of VIGS is dependent on the virus and maintenance of it is virus independent.
在感染携带八氢番茄红素去饱和酶（PDS）插入片段的马铃薯X病毒（PVX）载体的本氏烟草植株中，PDS基因被沉默；在感染PVX - GFP的植株中，绿色荧光蛋白（GFP）转基因被沉默。这种病毒诱导的基因沉默（VIGS）是转录后和细胞质水平的，因为它针对的是PDS RNA的外显子而非内含子以及病毒RNA。尽管PDS和GFP RNA很可能通过相同机制被靶向，但VIGS表型在两个方面有所不同。在PVX - PDS感染的植株所有绿色组织中，PDS mRNA被VIGS靶向，而PVX - PDS不受影响。相反，GFP的VIGS靶向的是PVX - GFP。最初，GFP的VIGS在所有绿色组织中启动，这与PDS的VIGS情况相同。然而，感染30天后，GFP的VIGS不再在新长出的叶片中启动，尽管它在已经启动的组织中持续存在。基于这些分析，我们提出了一个VIGS模型，其中VIGS的启动依赖于病毒，而其维持则与病毒无关。
