Chiang T Y
Department of Biology, Cheng-Kung University, Tainan, Taiwan.
Genome. 2000 Dec;43(6):1090-4.
Dumolin-Lapégue et al. (Mol. Biol. Evol. 15: 1321-1331. 1998) suggested that recurrent inversions of a 4-bp sequence of the mtDNA nad4-1/2 locus due to intramolecular recombination were responsible for the disassociation of chloroplast and mitochondrial genomes of French oaks. Based on their PCR-RFLP (PCR-restriction fragment length polymorphism) data obtained from three noncoding spacers, a minimum spanning network representing the phylogeny of the cpDNA was reconstructed. The mapping of alleles b and c of the mtDNA nad4-1/2 locus on the cpDNA network revealed a nonrandom distribution, which contradicted the expected patterns when repeated, and ongoing inversions had been occurring. The fact that polymorphisms (a mixed c + d type) were mostly restricted to the interior nodes of the network, which represented ancient haplotypes and geographically coincided with probable glacial refugia in southern Europe, agreed with a migrant-pool model. Evidence of a widespread pattern of polymorphism distribution indicated that mtDNA haplotypes were likely to be more ancient than the cpDNA haplotypes. Lineage sorting, due to relative age of cpDNA vs. mtDNA, plus the specific migratory mode, which recruited colonists from a random sample of resource populations during glacial expansion (thereby extending the lineage sorting period, LSP), may have resulted in the disassociation of chloroplast and mitochondrial genomes in oaks.
迪莫林 - 拉佩格等人（《分子生物学与进化》15: 1321 - 1331. 1998）提出，由于分子内重组导致线粒体DNA nad4 - 1/2位点的一个4碱基对序列反复倒位，是法国橡树叶绿体和线粒体基因组解离的原因。基于从三个非编码间隔区获得的PCR - RFLP（聚合酶链反应 - 限制性片段长度多态性）数据，重建了一个代表叶绿体DNA系统发育的最小生成网络。线粒体DNA nad4 - 1/2位点的等位基因b和c在叶绿体DNA网络上的映射显示出非随机分布，这与重复发生且正在进行倒位时的预期模式相矛盾。多态性（混合的c + d类型）大多局限于网络内部节点这一事实，这些内部节点代表古老单倍型且在地理上与南欧可能的冰川避难所重合，这与迁移池模型相符。多态性分布广泛模式的证据表明，线粒体DNA单倍型可能比叶绿体DNA单倍型更古老。由于叶绿体DNA与线粒体DNA的相对年龄，加上特定的迁移模式，即在冰川扩张期间从资源种群的随机样本中招募殖民者（从而延长了谱系分选期，LSP），可能导致了橡树中叶绿体和线粒体基因组的解离。
