Svanella-Dumas Laurence, Candresse Thierry, Hullé Maurice, Marais Armelle
INRA, UMR 1332 de Biologie du Fruit et Pathologie, CS20032 Villenave d'Ornon, France ; Univ. Bordeaux, UMR 1332 de Biologie du Fruit et Pathologie, CS20032 Villenave d'Ornon, France.
PLoS One. 2013 Jun 18;8(6):e67231. doi: 10.1371/journal.pone.0067231. Print 2013.
A systematic search for viral infection was performed in the isolated Kerguelen Islands, using a range of polyvalent genus-specific PCR assays. Barley yellow dwarf virus (BYDV) was detected in both introduced and native grasses such as Poa cookii. The geographical distribution of BYDV and its prevalence in P. cookii were analyzed using samples collected from various sites of the archipelago. We estimate the average prevalence of BYDV to be 24.9% in P. cookii, with significant variability between sites. BYDV genetic diversity was assessed using sequence information from two genomic regions: the P3 open reading frame (ORF) (encoding the coat protein) and the hypervariable P6 ORF region. The phylogenetic analysis in the P3 region showed that BYDV sequences segregate into three major lineages, the most frequent of which (Ker-I cluster) showed close homology with BYDV-PAV-I isolates and had very low intra-lineage diversity (0.6%). A similarly low diversity was also recorded in the hypervariable P6 region, suggesting that Ker-I isolates derive from the recent introduction of BYDV-PAV-I. Divergence time estimation suggests that BYDV-PAV-I was likely introduced in the Kerguelen environment at the same time frame as its aphid vector, Rhopalosiphum padi, whose distribution shows good overlap with that of BYDV-Ker-I. The two other lineages show more than 22% amino acid divergence in the P3 region with other known species in the BYDV species complex, indicating that they represent distinct BYDV species. Using species-specific amplification primers, the distribution of these novel species was analyzed. The high prevalence of BYDV on native Poaceae and the presence of the vector R. padi, raises the question of its impact on the vulnerable plant communities of this remote ecosystem.
在孤立的凯尔盖朗群岛进行了一项针对病毒感染的系统搜索，使用了一系列多价属特异性聚合酶链式反应（PCR）检测方法。在引入的和本地的禾本科植物如库克早熟禾中检测到了大麦黄矮病毒（BYDV）。利用从该群岛不同地点采集的样本，分析了BYDV的地理分布及其在库克早熟禾中的流行情况。我们估计BYDV在库克早熟禾中的平均流行率为24.9%，不同地点之间存在显著差异。利用来自两个基因组区域的序列信息评估了BYDV的遗传多样性：P3开放阅读框（ORF）（编码外壳蛋白）和高变P6 ORF区域。P3区域的系统发育分析表明，BYDV序列分为三个主要谱系，其中最常见的（Ker-I簇）与BYDV-PAV-I分离株显示出密切的同源性，并且谱系内多样性非常低（0.6%）。在高变P6区域也记录到了类似的低多样性，这表明Ker-I分离株源自BYDV-PAV-I的近期引入。分歧时间估计表明，BYDV-PAV-I可能在与其蚜虫传播媒介禾谷缢管蚜相同的时间框架内被引入凯尔盖朗环境，禾谷缢管蚜的分布与BYDV-Ker-I的分布有很好的重叠。另外两个谱系在P3区域与BYDV物种复合体中的其他已知物种有超过22%的氨基酸差异，表示它们代表不同的BYDV物种。使用物种特异性扩增引物分析了这些新物种的分布。BYDV在本地禾本科植物上的高流行率以及传播媒介禾谷缢管蚜的存在，引发了其对这个偏远生态系统中脆弱植物群落影响的问题。
