Suppression of gene silencing: A general strategy used by diverse DNA and RNA viruses of plants
Suppression of gene silencing: A general strategy used by diverse DNA and RNA viruses of plants
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DOI：
10.1073/pnas.96.24.14147
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发表时间：
1999-11-23
影响因子：
11.1
通讯作者：
Baulcombe, DC
中科院分区：
文献类型：
--
作者：
Voinnet, O;Pinto, YM;Baulcombe, DC
在转基因和非转基因植物中，病毒都是一种类似于转录后基因沉默（PTGS）的防御机制的启动者和靶标。最近，人们发现potyvirus和cucummovirus编码了抑制这种防御机制的致病性决定因子。在这里，我们测试了不同类型的病毒抑制PTGS的能力。将具有PTGS绿色荧光蛋白转基因基因的benthamiana与一系列不相关的病毒和多种产生病毒致病性因子的马铃薯病毒X载体感染，通过重新激活绿色荧光来评估PTGS在植物中的抑制作用，并通过分子分析加以证实。这些实验鉴定出三种PTGS的抑制子，表明PTGS的抑制被广泛用作DNA和RNA病毒的防御策略。然而，病毒间抑制的空间格局和程度差异很大。在一种极端情况下，有些病毒可以抑制所有感染叶片的所有组织，而另一些病毒只能抑制新生叶片的静脉。这种变异甚至存在于密切相关的痘病毒组成员之间。总之，这些结果表明，病毒编码的基因沉默抑制因子具有不同的作用模式，针对宿主基因沉默机制的不同组成部分，并且与基因沉默机制相关的宿主和病毒组成部分存在动态进化。
In transgenic and nontransgenic plants, viruses are both initiators and targets of a defense mechanism that is similar to posttranscriptional gene silencing (PTGS), Recently, it was found that potyviruses and cucumoviruses encode pathogenicity determinants that suppress this defense mechanism. Here, we test diverse virus types for the ability to suppress PTGS. Nicotiana benthamiana exhibiting PTGS of a green fluorescent protein transgene were infected with a range of unrelated Viruses and various potato virus X vectors producing viral pathogenicity factors, Upon infection, suppression of PTGS was assessed in planta through reactivation of green fluorescence and confirmed by molecular analysis, These experiments led to the identification of three suppressors of PTGS and showed that suppression of PTGS is widely used as a counter-defense strategy by DNA and RNA viruses. However, the spatial pattern and degree of suppression Varied extensively between viruses. At one extreme, there are Viruses that suppress in all tissues of ail infected leaves, whereas others are able to suppress only in the veins of new emerging leaves, This Variation existed even between closely related members of the potexvirus group. Collectively, these results suggest that virus-encoded suppressors of gene silencing have distinct modes of action, are targeted against distinct components of the host gene-silencing machinery, and that there is dynamic evolution of the host and viral components associated with the gene-silencing mechanism.