Phylogenetic analysis of "Candidatus Phytoplasma australiense" reveals distinct populations in New Zealand
Phylogenetic analysis of "Candidatus Phytoplasma australiense" reveals distinct populations in New Zealand
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DOI：
10.1094/phyto-96-0838
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发表时间：
2006-08-01
期刊：
影响因子：
3.2
通讯作者：
Beever, Ross E.
中科院分区：
文献类型：
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作者：
Andersen, Mark T.;Newcomb, Richard D.;Beever, Ross E.
植物原体“Candidatus phytoplasma australiense”已在新西兰和澳大利亚报道，特别是自20世纪70年代以来，它已与一系列寄主植物有关。来自4个不同寄主属的36株新西兰（New Zealand， NZ）菌株的tuf基因部分序列显示出9个不同的变异，聚在两个不同的类群中，与寄主或地理区域没有明显的相关性。对这些序列的系统发育分析，连同从澳大利亚分离的序列，揭示了三个不同的分支：一个仅在澳大利亚发现，一个仅在新西兰发现，第三个来自两国的代表。这些分裂与16-23S rRNA内部转录间隔区观察到的差异一致；因此，我们得出结论，它们代表三个不同的亚群：tuf 1， tuf 2和tuf 3。我们通过比较丝瓜巫婆的-broom植物原体和“Candidatus phytoplasma australiense”的完整凝灰质基因序列，计算出同义替代率，估计了三个分支的分化时间。使用1.1亿年的校准日期，所有进化枝形成共同祖先的估计时间（600万至900万年前）表明，在中新世出现分化，远在新西兰和澳大利亚的地质分离之后。
The phytoplasma "Candidatus Phytoplasma australiense" has been reported from New Zealand and Australia, where it has been associated with a range of host plants, especially since the 1970s. Partial tuf gene sequences of 36 New Zealand (NZ) isolates from four different host genera revealed nine different variants, which clustered into two distinct groups without any obvious correlation with host or geographic region. Phylogenetic analysis of these sequences, together with those available from Australian isolates, revealed three distinct clades: one found solely in Australia, one found solely in NZ, and a third with representatives from both countries. These divisions are consistent with differences observed in the 16-23S rRNA internal transcribed spacer region; therefore, we conclude that they represent three distinct subgroups: tuf 1, tuf 2, and tuf 3. We estimated a time of divergence for the three clades based on a synonymous substitution rate calculated by comparing the complete tuf gene sequence from the Loofah witches'-broom phytoplasma and "Candidatus Phytoplasma australiense". Using a calibration date of 110 million years, the estimated time to a common ancestor for all clades (6 to 9 million years ago) suggests divergence during the Miocene, well after the geological separation of NZ and Australia.