Vassilakos N, Vellios E K, Brown E C, Brown D J, MacFarlane S A
Department of Pathology, Scottish Crop Research Institute, Dundee, Invergowrie, DD2 5DA, United Kingdom.
Virology. 2001 Jan 20;279(2):478-87. doi: 10.1006/viro.2000.0677.
Analysis of RNA2 of TRV PaY4 showed it to be recombinant, carrying 3'-terminal sequences derived from RNA1. Virus produced using an infectious cDNA clone of PaY4 RNA2 was nematode transmissible, demonstrating that natural TRV recombinant isolates are not necessarily defective. Mutations introduced into PaY4 RNA2 showed that the 2b gene, but not the 2c gene, is required for transmission by both Paratrichodorus pachydermus and P. anemones nematodes. Experiments examined whether infection of plants with two different virus clones would impact upon nematode transmission of either virus. Simultaneous inoculation with TRV clones expressing green or red fluorescent proteins revealed that mixing of the two virus populations did not occur, although, in roots, adjacent cells were found containing green- or red-tagged viruses. Subsequently, in similar experiments it was found that a TRV PaY4 2b mutant was transmitted when combined with wild-type TRV PaY4. Also, transmission of a 2b mutant of an in vitro TRV/PEBV recombinant virus (TRV-C1) occurred after coinfection with wild-type virus. Thus, the tobravirus 2b transmission protein is trans-acting. Although TRV PaY4 and TRV PpK20 are both transmitted by P. pachydermus, a 2b mutant of TRV PaY4 was not transmitted when coinoculated to plants with TRV PpK20.
对烟草脆裂病毒PaY4的RNA2分析表明它是重组体，携带源自RNA1的3'末端序列。使用PaY4 RNA2的感染性cDNA克隆产生的病毒可被线虫传播，这表明天然的烟草脆裂病毒重组分离株不一定有缺陷。导入PaY4 RNA2的突变表明，2b基因而非2c基因是厚皮拟毛刺线虫和银拟毛刺线虫传播所必需的。实验研究了用两种不同病毒克隆感染植物是否会影响任何一种病毒的线虫传播。同时接种表达绿色或红色荧光蛋白的烟草脆裂病毒克隆表明，尽管在根中发现相邻细胞含有绿色或红色标记的病毒，但两种病毒群体并未混合。随后，在类似实验中发现，TRV PaY4 2b突变体与野生型TRV PaY4结合时可被传播。此外，体外烟草脆裂病毒/豌豆早褐病毒重组病毒（TRV-C1）的2b突变体在与野生型病毒共感染后可被传播。因此，烟草脆裂病毒2b传播蛋白具有反式作用。虽然TRV PaY4和TRV PpK20都可被厚皮拟毛刺线虫传播，但TRV PaY4的2b突变体与TRV PpK20共同接种到植物上时不能被传播。
