《生命科学》 2012, 24(5): 399-403
摘 要：摘 要：外源基因在不同的植物转基因株系间会呈现很大的表达差异，甚至出现同源共抑制现象，即转基因在其自身不表达的同时也造成与其同源的内源基因的沉默。转基因沉默和同源共抑制主要包括转录水平沉默(transcriptional gene silencing， TGS) 和转录后水平沉默(post-transcriptional gene silencing， PTGS)。高度转录的外源基因所产生的紊乱RNA 触发了RNA 干涉的机器，是造成转基因沉默和同源共抑制的主要原因。目前，介绍同源共抑制机理的综述很多，但是介绍其克服方法的综述却很少。为了减少转基因株系差异，得到稳定表达的转基因株系，研究者提出了一系列消除转基因沉默和同源共抑制的措施，包括筛选单拷贝株系、利用PTGS 突变体材料、利用病毒的RNA 干涉抑制因子、利用植物的紊乱RNA 清除蛋白以及构建新型的转基因载体等。对上述方法进行综述，并比较其优劣。
关键词：同源共抑制；转录水平基因沉默；转录后水平基因沉默；RNA 干涉抑制
Abstract: Abstract: Pronounced variability of transgene expression and transgene silencing are commonly observed among independent plant lines transformed with the same construct. Transgenes can also cause the silencing of endogenous plant genes if they are sufficiently homologous， a phenomenon known as homologous co suppression. Homologousco-suppression occurs transcriptionally and post-transcriptionally but predominantly post-transcriptionally. A major reason for transgene silencing and homologous co-suppression is that aberrant RNA produced by highly transcribed transgenes triggers the RNA interfering machinery of plant cells. At present， there are many reviews about the mechanism of homologous co-suppression， but rarely toward the method to eliminate it. In order to obtain stable level of transgene expression， researchers have proposed a series of measures to eliminate homologous cosuppression， including screening single-copy transformants， using PTGS mutants as a transformation background， using viral suppressors of RNA silencing， using plant proteins against aberrant RNA， and construction of new transgenic vectors， etc. We addressed and compared these methods here.
Key words: homologous co-suppression; transcriptional gene silencing; post-transcriptional gene silencing; suppression of RNA silencing
