Fraile A, Malpica J M, Aranda M A, Rodríguez-Cerezo E, García-Arenal F
Departamento de Biotecnología, E.T.S. Ingenieros Agrónomos, Ciudad Universitaria, Madrid, Spain.
Virology. 1996 Sep 1;223(1):148-55. doi: 10.1006/viro.1996.0463.
The variability and genetic structure of tobacco mild green mosaic tobamovirus (TMGMV) was analyzed in a collection of isolates from Nicotiana glauca plants from Australia, California, Spain, and the east Mediterranean Basin. Ribonuclease protection was assayed on 53 isolates with six probes representing 85% of the TMGMV genome. Results showed that conserved domains in the TMGMV genome were different for each geographic population. The nucleotide sequence of two regions of the TMGMV genome was determined for 33 isolates. Nucleotide diversity values were smaller than those reported for other RNA genomes. For each population, genetic diversity was not related to the size of the area from which the isolates were collected, and was particularly small for Australia and Spain. Diversity values indicated population differentiation, which was largest between the less diverse Spanish and Australian populations. Nucleotide diversity values for nonsynonymous vs synonymous positions indicate moderate negative selection, except for the Spanish population for which it gave evidence of positive selection. On the whole, our data indicate that the low genetic diversity for this plant virus may be due to different factors such as positive and negative selection or the recent colonization of new areas or host plants. The intensity of these factors appears to be different for the various TMGMV geographical populations.
对来自澳大利亚、加利福尼亚、西班牙和东地中海盆地的烟草淡绿花叶烟草花叶病毒（TMGMV）分离株进行了变异性和遗传结构分析。用代表TMGMV基因组85%的六种探针，对53个分离株进行了核糖核酸酶保护分析。结果表明，TMGMV基因组中的保守结构域在每个地理种群中都有所不同。测定了33个分离株TMGMV基因组两个区域的核苷酸序列。核苷酸多样性值小于其他RNA基因组报道的值。对于每个种群，遗传多样性与分离株收集区域的大小无关，澳大利亚和西班牙的遗传多样性尤其小。多样性值表明种群分化，在多样性较低的西班牙和澳大利亚种群之间分化最大。非同义与同义位点的核苷酸多样性值表明存在适度的负选择，但西班牙种群显示出正选择的证据。总体而言，我们的数据表明，这种植物病毒的低遗传多样性可能是由于正负选择、新区域或宿主植物的近期定殖等不同因素造成的。这些因素的强度在不同的TMGMV地理种群中似乎有所不同。
