中文摘要：

以模式植物拟南芥（Arabidopsis thaliana）和烟草（Nicotiana tabacum）及PRSV寄主植物番木瓜（CaricapapayaL.）作为试验材料,开展了番木瓜环斑病毒外壳蛋白基因dsRNA介导的PRSV病原抗性的研究。利用农杆菌介导法将番木瓜环斑病毒外壳蛋白CP基因反向重复表达载体pHellsgate12-CPIR（简称PHG12-CPIR）分别转化到烟草和拟南芥中,获得阳性植株,并利用渗透法和农杆菌介导的瞬时表达体系将pHG12-CPIR载体导入到番木瓜中。对转基因植株进行攻毒试验并分析了其抗病性。在接种3~7d内,在拟南芥和番木瓜上转基因植株的发病情况较轻,而野生型植株叶片与转基因植株相比,均表现出不同程度的黄化、皱缩和枯斑等症状。在接种PRSV后,番木瓜和拟南芥转化植株表现症状的叶片的比例与对照相比,结果显著低于对照,而在烟草植株上症状表现的差异不明显。在3种植物上RT-PCR检测结果显示,在接种番木瓜环斑病毒PRSV后,野生型植株中有高浓度的病毒积累,而转pHG12-CPIR基因植株中几乎没有病毒积累,推测转pHG12-CPIR基因植株中瞬时表达系统已启动RNAi机制抑制了CP基因的表达。

英文摘要：

Tobacco（Nicotiana tabacum）,Arabidopsis thaliana,and host papaya（Carica papaya L.）of PRSV were used as model plant materials to testing whether RNAi could mediate resistance to papaya ringspot virus（PRSV）.The agrobacterium was harbored with pHellsgate12-CPIR containing structured inverted sequences of the CP gene of PRSV,where were transformed into the tobacco and Arabidopsis.We also conducted an Agrobacterium-mediated transient expression experiment by infiltration in papaya.The three transgenic plants inoculated with PRSV were tested for resistance to PRSV.After PRSV challenge-inoculation for 3 to 7 days,leaves of the wild type plants displayed symptoms of necrosis,wrinkling and/or chlorosis,and the scale of the abnormal leaves in the transgenic plants was significantly lower than that of the wild type when the PRSV were inoculated in papaya and Arabidopsis separately.However,the difference in symptoms was not significant in transgenic tobacco and the control wild plant.We carried out a RT-PCR experiment on the three kinds of plants.The expression of CP mRNA was detected in the wild type plants infected with PRSV,but not in the transgenic plants.These results suggest that the transgenic plants may induce the RNAi process to resist PRSV.