In recent years,RNA silencing mechanism in plants has been undestood increasingly clear,and small RNAs(sRNAs)plays an important role in the progress. In this paper,the mechanism of RNA silencing in plants, main pathways of RNA silencing and the role of RNA silencing in defencing foreign DNA sequences are summarized specifically. In addition,important actions of gene silencing suppressor encoded by DNA viruses against host silencing response are introduced. It is necessary to further study the RNA silencing. This paper also specifically analyzes problems that need to research,and provides basis for virus resistance breeding.%近年来，人们对植物中 RNA 沉默机制的的认识日渐清晰，小 RNAs 在其中发挥重要作用。文章综述了植物中 RNA 沉默的机制、RNA 沉默的主要途径及其在防御外源 DNA 序列入侵过程中的主要功能。并简要介绍了由 DNA 病毒编码的基因沉默抑制子在对抗宿主沉默反应的作用。文章最后阐述了对 RNA 沉默进行深入研究的必要性，对需要研究的问题进行了分析，为抗病毒作物育种提供了有力依据。
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