CIRAD, UMR BGPI, Montpellier, France.
J Virol. 2013 Aug;87(15):8624-37. doi: 10.1128/JVI.00899-13. Epub 2013 May 29.
Plant pararetroviruses integrate serendipitously into their host genomes. The banana genome harbors integrated copies of banana streak virus (BSV) named endogenous BSV (eBSV) that are able to release infectious pararetrovirus. In this investigation, we characterized integrants of three BSV species-Goldfinger (eBSGFV), Imove (eBSImV), and Obino l'Ewai (eBSOLV)-in the seedy Musa balbisiana Pisang klutuk wulung (PKW) by studying their molecular structure, genomic organization, genomic landscape, and infectious capacity. All eBSVs exhibit extensive viral genome duplications and rearrangements. eBSV segregation analysis on an F1 population of PKW combined with fluorescent in situ hybridization analysis showed that eBSImV, eBSOLV, and eBSGFV are each present at a single locus. eBSOLV and eBSGFV contain two distinct alleles, whereas eBSImV has two structurally identical alleles. Genotyping of both eBSV and viral particles expressed in the progeny demonstrated that only one allele for each species is infectious. The infectious allele of eBSImV could not be identified since the two alleles are identical. Finally, we demonstrate that eBSGFV and eBSOLV are located on chromosome 1 and eBSImV is located on chromosome 2 of the reference Musa genome published recently. The structure and evolution of eBSVs suggest sequential integration into the plant genome, and haplotype divergence analysis confirms that the three loci display differential evolution. Based on our data, we propose a model for BSV integration and eBSV evolution in the Musa balbisiana genome. The mutual benefits of this unique host-pathogen association are also discussed.
植物拟反转录病毒偶然整合到宿主基因组中。香蕉基因组中含有整合的香蕉束顶病毒（BSV）副本，称为内源性 BSV（eBSV），它们能够释放传染性拟反转录病毒。在这项研究中，我们通过研究其分子结构、基因组组织、基因组景观和感染能力，对三种 BSV 物种——金手指（eBSGFV）、伊莫夫（eBSImV）和 Obino l'Ewai（eBSOLV）的整合子进行了表征。所有 eBSV 都表现出广泛的病毒基因组重复和重排。在 PKW 的 F1 群体中进行的 eBSV 分离分析结合荧光原位杂交分析表明，eBSImV、eBSOLV 和 eBSGFV 各自位于单个基因座上。eBSOLV 和 eBSGFV 包含两个不同的等位基因，而 eBSImV 具有两个结构相同的等位基因。对后代中表达的 eBSV 和病毒粒子进行基因分型表明，每种物种的只有一个等位基因是可感染的。由于两个等位基因相同，因此无法确定 eBSImV 的感染等位基因。最后，我们证明 eBSGFV 和 eBSOLV 位于参考 Musa 基因组的 1 号染色体上，而 eBSImV 位于最近发表的 Musa 基因组的 2 号染色体上。eBSV 的结构和进化表明它们是依次整合到植物基因组中的，并且单倍型分化分析证实这三个基因座显示出不同的进化。基于我们的数据，我们提出了一个 BSV 整合和 Musa balbisiana 基因组中 eBSV 进化的模型。还讨论了这种独特的宿主-病原体共生关系的互利性。
