正向和反向重复RNA介导的抗马铃薯Y病毒基因工程比较研究

 RNA介导的病毒抗性与RNA沉默现象密切相关。反向重复cDNA序列(IR)的转录产物往往形成双链RNA结构,而双链RNA是诱发RNA沉默的有效因子。据此,本研究通过体外合成马铃薯Y病毒坏死株系衣壳蛋白基因(PVY^N-CP)5'端反向重复cDNA序列和正向重复cDNA序列(DR),分别构建植物表达载体pROK-IR和pROK-DR,利用农杆菌介导方法转化烟草NC89,比较这2种转基因烟草在RNA介导抗病性方面的差异。抗病性检测表明,转化IR和DR的转基因烟草均可获得抗病程度达到免疫的植株,但转化IR序列可大大提高抗病植株在转基因植株中的比例。分析结果表明所获得的抗病性为RNA介导的抗病性,是RNA沉默的结果。这一研究结果为利用IR策略进行抗病毒遗传育种提供了理论依据,并为讲一步开展RNA介导抗病性的机制研究奠宗了基础。

Comparison of resistance to Potato virus Y mediated by direct and inverted repeats of the coat protein gene segments in transgenic tobacco plants

It has been demonstrated that RNA-mediated resistance to virus infection in plants is associated with RNA silencing, in which dsRNA in the transgenic plants may play an important role in triggering the silencing process. In this research, we designed cDNA constructs using direct repeat (DR) and inverted repeat (IR) of the coat protein gene segments of Potato virus Y (PVY) ,or introduced these constructs into tobacco plants via Agrobacterium tumefaciens-mediated transformation system. Resistant assays of the transgenic plants showed that highly resistant plants to PVY infection were obtained in both DR- and IR-transgenic plants. However, higher proportion of resistant plants was obtained from the IR-transgenic plants than that from DR-transgenic plants. Further analysis demonstrated that the resistance was RNA-mediated. These results indicate that using IR constructs of viral gene segments as transgenes may be a feasible strategy to produce virus-resistant plants by genetic engineering.