Kim Hyoung Tae, Chase Mark W
College of Agriculture and Life Sciences, Kyungpook University, Daegu, Korea.
Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, United Kingdom.
PLoS One. 2017 Nov 15;12(11):e0187318. doi: 10.1371/journal.pone.0187318. eCollection 2017.
In this paper, we compare ndh genes in the plastid genome of many Cymbidium species and three closely related taxa in Orchidaceae looking for evidence of ndh gene degradation. Among the 11 ndh genes, there were frequently large deletions in directly repeated or AT-rich regions. Variation in these degraded ndh genes occurs between individual plants, apparently at population levels in these Cymbidium species. It is likely that ndh gene transfers from the plastome to mitochondrial genome (chondriome) occurred independently in Orchidaceae and that ndh genes in the chondriome were also relatively recently transferred between distantly related species in Orchidaceae. Four variants of the ycf1-rpl32 region, which normally includes the ndhF genes in the plastome, were identified, and some Cymbidium species contained at least two copies of that region in their organellar genomes. The four ycf1-rpl32 variants seem to have a clear pattern of close relationships. Patterns of ndh degradation between closely related taxa and translocation of ndh genes to the chondriome in Cymbidium suggest that there have been multiple bidirectional intracellular gene transfers between two organellar genomes, which have produced different levels of ndh gene degradation among even closely related species.
在本文中，我们比较了多种大花蕙兰物种以及兰科三个近缘类群质体基因组中的ndh基因，以寻找ndh基因降解的证据。在11个ndh基因中，直接重复区域或富含AT的区域经常出现大的缺失。这些降解的ndh基因在个体植株之间存在变异，显然在这些大花蕙兰物种的种群水平上也是如此。ndh基因从质体基因组转移到线粒体基因组（线粒体基因组）的现象可能在兰科中是独立发生的，并且线粒体基因组中的ndh基因也相对较近地在兰科远缘物种之间发生了转移。鉴定出了ycf1-rpl32区域的四个变体，该区域通常在质体基因组中包含ndhF基因，并且一些大花蕙兰物种在其细胞器基因组中至少含有该区域的两个拷贝。这四个ycf1-rpl32变体似乎有明显的亲缘关系模式。大花蕙兰近缘类群之间的ndh降解模式以及ndh基因向线粒体基因组的易位表明，两个细胞器基因组之间存在多次双向细胞内基因转移，这在即使是近缘物种中也产生了不同程度的ndh基因降解。
