Studies on tomato golden mosaic virus and African cassava mosaic virus suggested that virion sense promoter was trans -activated in transient expression by A C2 encoded by geminivirus. The AC2 gene fragment of cott on leaf curl virus (CLCuV) was obtained from total DNA of CLCuV infected tobacco leaves by polymerase chain reaction, and the amplified DNA fragment was cloned into vector. Transient expres sion vectors were constructed by fusing the AC2 gene fra gment with CaMV 35S prom oter and nopaline terminator. These constructs were delivered into tobacco [ WT(Nicotiana tabacum L.) and cotton ( Gossypium hirsutum L.) leaf cells for transient expression by particle bombardment. Results indicated that activity of virion sense promoter was activated by AC2 and increased remarkably. However, the activity of trans-activated virion sense promoter was still lower than that of complementary sense promoter. Expression pattern of transactivated virion sense promoter was similar to that of complementary sense promoter with the high activity in both mesophyll and vascular of leaf vein. In this paper, the expression behavior of AC2 in Agrobacterium -mediated transgenic plants was also discussed.
棉花曲叶病毒反式作用因子AC2 的功能初探
谢迎秋1 孟蒙1 朱祯1* 吴茜1 徐鸿林1 刘玉乐2
（1. 中国科学院遗传研究所，北京100101；2. 中国科学院微生物研究所，北京100080）
摘要：有关非洲木薯花叶病毒(ACMV)、番茄金色花叶病毒(TGMV)的研究表明，双生病毒编码的反式作用因子AC2反式激活病毒链基因启动子的瞬时表达。以棉花曲叶病毒(CLCuV)侵染的烟草叶片组织总DNA为模板，通过聚合酶链反应扩增CLCuV的AC2基因片段并插入克隆载体。将AC2置于CaMV35S启动子下构建了瞬时表达载体。通过基因枪法将质粒载体导入烟草（Nicotianatabacum L.）和棉花(Gossypium hirsutum L.)叶片细胞中进行瞬时表达，结果表明，在反式作用因子AC2的激活下，病毒链基因启动子驱动的GUS活性明显增强，然而激活后的病毒链基因启动子的活性仍低于互补链基因方向启动子；其表达方式与互补链基因启动子相似，即在叶肉及叶脉维管组织均有较高的活性。还探讨了AC2在土壤杆菌介导的转基因植物中的表达行为。
关键词： 双生病毒；启动子；反式作用因子；棉花；烟草；基因枪
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