论文部分内容阅读
应用基因突变技术，在烟草黄矮双生病毒（Ｔｏｂａｃｏｙｅｌｏｗｄｗａｒｆｇｅｍｉｎｉｖｉｒｕｓ，简称ＴｏｂＹＤＶ）基因组的正义和反义链引入或缺失碱基，从而构建成一系列移码突变体。这些突变体在个别感染的情况下，全部丧失了系统侵染三生烟植株的能力，但是，成对地进行接种，能发生持久的互补作用，重新获得系统侵染的能力。突变体的互补作用发生在重组之前。在个别感染的叶块组织中，各种反义链突变体丧失了复制能力，然而，突变体Ｖ１－、Ｖ２－和Ｖ１－Ｖ２－能高度复制，表明反义链读码框编码产物为复制所必需，Ｖ１和Ｖ２读码框编码产物与复制无关，而为病毒的转移所必需。从Ｖ１－和Ｖ２－转化叶块中再生转基因植株，发现Ｖ１－和Ｖ２－都能在植株中维持复制，但是，只有Ｖ１－引起典型的病症，表明Ｖ１编码产物与病症出现无关。这些结果将为发展ＴｏｂＹＤＶ为载体，在寄主植物中高度复制和表达外源基因提供依据。
A series of frameshift mutants were constructed by introducing or deleting bases in the sense and antisense strands of Tobacoyelowdwarfgeminivirus (TobYDV) genome by using gene mutation technique. In the case of individual infections, all of these mutants have lost their ability to systematically infect the Nicotiana benthamiana plants. However, inoculation in pairs leads to lasting complementarity and regains the ability to infect the system. The complementarity of the mutants occurs before recombination. In individual infected leaf tissue, various antisense strand mutants lost their ability to replicate. However, the mutants V1-, V2- and V1-V2- were highly replicable, indicating that the antisense strand reading frame encoded product was duplicated Necessary, V1 and V2 reading frame encoded product has nothing to do with the replication, but necessary for the transfer of the virus. Transgenic plants were regenerated from V1- and V2-transformed leaves and both V1- and V2- were found to replicate in the plants, however, only V1- caused the typical condition, indicating that the V1 encoded product was not associated with the appearance of the disease. These results will provide a basis for the development of TobYDV as a vector to highly replicate and express foreign genes in host plants.