Baulcombe D C
Sainsbury Laboratory, John Innes Centre, Norwich, UK.
Plant Mol Biol. 1996 Oct;32(1-2):79-88. doi: 10.1007/BF00039378.
Post-transcriptional gene silencing in transgenic plants is the manifestation of a mechanism that suppresses RNA accumulation in a sequence-specific manner. The target RNA species may be the products of transgenes, endogenous plant genes or viral RNAs. For an RNA to be a target it is necessary only that it has sequence homology to the sense RNA product of the transgene. There are three current hypotheses to account for the mechanism of post transcriptional gene silencing. These models all require production of an antisense RNA of the RNA targets to account for the specificity of the mechanism. There could be either direct transcription of the antisense RNA from the transgene, antisense RNA produced in response to over expression of the transgene or antisense RNA produced in response to the production of an aberrant sense RNA product of the transgene. To determine which of these models is correct it will be necessary to find out whether transgene methylation, which is frequently associated with the potential of transgenes to confer post-transcriptional gene silencing, is a cause or a consequence of the process.
转基因植物中的转录后基因沉默是一种以序列特异性方式抑制RNA积累的机制的表现。目标RNA种类可能是转基因产物、植物内源基因或病毒RNA。要使一种RNA成为靶标，只需它与转基因的正义RNA产物具有序列同源性。目前有三种假说来解释转录后基因沉默的机制。这些模型都需要产生RNA靶标的反义RNA来解释该机制的特异性。反义RNA可能直接由转基因转录产生，也可能是因转基因的过表达而产生，或者是因转基因异常正义RNA产物的产生而产生。为了确定这些模型中哪一个是正确的，有必要弄清楚转基因甲基化（它常常与转基因赋予转录后基因沉默的可能性相关）是该过程的原因还是结果。
