REGENERATION OF A FUNCTIONAL RNA VIRUS GENOME BY RECOMBINATION BETWEEN DELETION MUTANTS AND REQUIREMENT FOR COWPEA CHLOROTIC MOTTLE VIRUS 3A AND COAT GENES FOR SYSTEMIC INFECTION
REGENERATION OF A FUNCTIONAL RNA VIRUS GENOME BY RECOMBINATION BETWEEN DELETION MUTANTS AND REQUIREMENT FOR COWPEA CHLOROTIC MOTTLE VIRUS 3A AND COAT GENES FOR SYSTEMIC INFECTION
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DOI：
10.1073/pnas.87.5.1820
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发表时间：
1990-03-01
影响因子：
11.1
通讯作者：
AHLQUIST, P
中科院分区：
文献类型：
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作者：
ALLISON, R;THOMPSON, C;AHLQUIST, P
RNA 1和2的三分豇豆褪绿斑驳病毒（CCMV）基因组是足够的RNA复制在原生质体中，而系统感染的豇豆植物还需要RNA 3，它编码的3a非衣壳蛋白和外壳蛋白。通过使用具有生物活性的CCMVcDNA克隆，我们发现RNA 3基因的缺失阻断了系统性感染。因此，尽管一些植物RNA病毒能够系统传播而不发生寄生，但CCMV系统感染豇豆需要外壳基因和3a基因。当CCMVRNA 1和RNA 2与RNA 3的3a和外壳缺失突变体共接种时，30-60%的植株迅速发生系统感染。在这种感染中，从全身感染的叶片中回收的子代RNA既不包含起始缺失突变体，也不包含两个基因完整的单个全长RNA 3组分。在全长子代RNA中回收了作为人工标记引入外壳蛋白缺失突变体的核苷酸取代，证实了其重组性质。因此，植物中的分子间RNA重组可以从单独丧失系统传播能力的共接种突变体中拯救完整的感染性基因组。这些结果对修复由频繁的自然复制错误产生的缺陷基因组，新适应的RNA病毒在新宿主的共感染后可能出现，以及RNA病毒重组的进一步研究具有影响。
RNAs 1 and 2 of the tripartite cowpea chlorotic mottle virus (CCMV) genome are sufficient for RNA replication in protoplasts, whereas systemic infection of cowpea plants additionally requires RNA3, which encodes the 3a noncapsid protein and coat protein. By using biologically active CCMV cDNA clones, we find that deletions in either RNA3 gene block systemic infection. Thus, though some plant RNA viruses are able to spread systemically without encapsidation, both the coat and 3a genes are required for systemic infection of cowpeas by CCMV. When plants were coinoculated with CCMV RNAs 1 and 2 and both the 3a and coat deletion mutants of RNA3, 30-60% rapidly developed systemic infection. Progeny RNA recovered from systemically infected leaves in such infections contained neither of the starting deletion mutants but rather a single full-length RNA3 component with both genes intact. Nucleotide substitutions introduced into the coat protein deletion mutant as an artificial marker were recovered in the full-length progeny RNA, confirming its recombinant nature. Intermolecular RNA recombination in planta can, therefore, rescue a complete infectious genome from coinoculated mutants independently disabled for systemic spread. These results have implications for the repair of defective genomes produced by frequent natural replication errors, the possible emergence of newly adapted RNA viruses upon coinfection of new hosts, and further studies of RNA virus recombination.