AQUATIC PLANT SPECIATION AFFECTED BY DIVERSIFYING SELECTION OF ORGANELLE DNA REGIONS
AQUATIC PLANT SPECIATION AFFECTED BY DIVERSIFYING SELECTION OF ORGANELLE DNA REGIONS
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DOI：
10.1111/j.1529-8817.2011.01037.x
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发表时间：
2011-10-01
影响因子：
2.9
通讯作者：
Nozaki, Hisayoshi
中科院分区：
文献类型：
--
作者：
Kato, Syou;Misawa, Kazuharu;Nozaki, Hisayoshi
许多控制光合作用的基因都携带在叶绿体中。这些基因因物种而异。然而，尚未有证据表明细胞器基因参与植物物种形成的初始阶段。为了阐明水生植物物种形成的分子基础，我们重点研究了独特的植物物种 Chara braunii C. C. Gmel。栖息于浅层和深层淡水栖息地，并表现出基于栖息地的叶绿体 DNA (cpDNA) 的二态性。在这里，我们使用两种核 DNA (nDNA) 标记和 cpDNA 检查了 C. braunii 的“浅”和“深”亚群。尽管系统发育分析表明亚群之间存在核基因流动，但在 nDNA 和 cpDNA 区域均测量了两个亚群之间的遗传分化。基于 Tajima's D 的中性测试证明了作用于细胞器 DNA 区域的多样化选择。此外，在源自三个深层环境的底部土壤的培养物中检测到的cpDNA的“浅层”和“深层”单倍型表明，卵孢子（休眠合子）在两个生境之间的迁移发生，与来自田间收集的营养菌体的cpDNA完全基于生境的二态性无关。因此，这两个亚群因其不同的水生生境而受到高度选择，并表现出合子前的隔离，这代表了受基于生态的细胞器基因趋异选择影响的物种形成的初始过程。
Many of the genes that control photosynthesis are carried in the chloroplast. These genes differ among species. However, evidence has yet to be reported revealing the involvement of organelle genes in the initial stages of plant speciation. To elucidate the molecular basis of aquatic plant speciation, we focused on the unique plant species Chara braunii C. C. Gmel. that inhabits both shallow and deep freshwater habitats and exhibits habitat-based dimorphism of chloroplast DNA (cpDNA). Here, we examined the "shallow'' and "deep'' subpopulations of C. braunii using two nuclear DNA (nDNA) markers and cpDNA. Genetic differentiation between the two subpopulations was measured in both nDNA and cpDNA regions, although phylogenetic analyses suggested nuclear gene flow between subpopulations. Neutrality tests based on Tajima's D demonstrated diversifying selection acting on organelle DNA regions. Furthermore, both "shallow'' and "deep'' haplotypes of cpDNA detected in cultures originating from bottom soils of three deep environments suggested that migration of oospores (dormant zygotes) between the two habitats occurs irrespective of the complete habitat-based dimorphism of cpDNA from field-collected vegetative thalli. Therefore, the two subpopulations are highly selected by their different aquatic habitats and show prezygotic isolation, which represents an initial process of speciation affected by ecologically based divergent selection of organelle genes.