转基因植物内源基因与外源基因共抑制问题研究进展

Recent Advances on Cosuppression of Transgenes and Endogenous Genes in Transgenic Plants *

在植物基因工程研究中，有时外源转化基因和植物中同源的内源基因的表达均被抑制了，这种现象被称为共抑制。引起该现象的原因包括许多因素，有外源基因和与之同源的内源基因ＲＮＡ的转录量，ＤＮＡ的甲基化，ＴＤＮＡ的结构形式，ＲＮＡ依赖的ＲＮＡ聚合酶，非正常ＲＮＡ以及非等位配对等。其具体机制仍不清楚。最近的研究结果表明转基因植物对病毒的抗性在某些方面与共抑制有相似之处。两者都表现为外源转化基因转录水平很高而稳定ＲＮＡ的水平很低。本文综述了这方面的最新研究进展。

In transgenic plants,transgenes may be silenced together with the homologous endogenous genes in some cases.This phenomenon is called cosuppression.Many factors may be involved in causing this phenomenon.These factors include RNA quantities,DNA methylation,T DNA organizations,RNA dependent RNA polymerase,aberrant RNA and ectopic pairing etc.But the exact mechanism is not clear yet.Recent work demonstrates that virus resistant transgenic plant expressing PVX amplicon is similar to cosuppression in some respects.They both relate to high levels of transgene transcription and low steady state levels of RNA.This paper also summarizes the studies on cosuppression in the authers' laboratry.