Intracellular gene transfer in action:: Dual transcription and multiple silencings of nuclear and mitochondrial cox2 genes in legumes
Intracellular gene transfer in action:: Dual transcription and multiple silencings of nuclear and mitochondrial cox2 genes in legumes
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DOI：
10.1073/pnas.96.24.13863
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发表时间：
1999-11-23
影响因子：
11.1
通讯作者：
Palmer, JD
中科院分区：
文献类型：
--
作者：
Adams, KL;Song, KM;Palmer, JD
呼吸基因cox 2，通常存在于细胞核中，以前被证明在开花植物进化过程中，可能在豆类多样化过程中，功能性转移到细胞核中。为了寻找细胞内基因转移过程中新的中间阶段，并评估cox 2转移、激活和失活的进化时间和频率，我们检测了超过25个豆科植物属中核和线粒体（mt）cox 2的存在和表达，以及392个属中mt cox 2的存在。cox 2的转移和激活似乎发生在最近的豆科植物进化过程中，比以前推断的更近。在所研究的豆科植物中，cox 2基因代表了基因转移过程的许多中间阶段。9种豆科植物含有完整的细胞核和mt cox 2基因拷贝，尽管其中一些基因的转录本无法检测到。巴斯cox 2基因在7种豆科植物中转录，这些豆科植物在遗传学上散布着仅显示核或mt cox 2表达的物种。每个基因组中cox 2的失活已经以多种方式发生多次，包括可检测的转录本或转录本编辑的丢失以及部分到完全的基因丢失。系统发生学证据显示，细胞核和线粒体cox 2的单独失活数目（3-5）大致相同，这表明在植物中，线粒体cox 2相对于细胞核位置没有选择优势。目前的分布cox 2的存在和表达之间的细胞核和cox 2基因的研究豆类可能是机会突变沉默的结果。
The respiratory gene cox2, normally present in the mitochondrion, was previously shown to have been functionally transferred to the nucleus during flowering plant evolution, possibly during the diversification of legumes. To search for novel intermediate stages in the process of intracellular gene transfer and to assess the evolutionary timing and frequency of cox2 transfer, activation, and inactivation, we examined nuclear and mitochondrial (mt) cox2 presence and expression in over 25 legume genera and mt cox2 presence in 392 genera. Transfer and activation of cox2 appear to have occurred during recent legume evolution, more recently than previously inferred. Many intermediate stages of the gene transfer process are represented by cox2 genes in the studied legumes. Nine legumes contain intact copies of both nuclear and mt cox2, although transcripts could not be detected for some of these genes. Bath cox2 genes are transcribed in seven legumes that are phylogenetically interspersed with species displaying only nuclear or mt cox2 expression. Inactivation of cox2 in each genome has taken place multiple times and in a variety of ways, including loss of detectable transcripts or transcript editing and partial to complete gene loss. Phylogenetic evidence shows about the same number (3-5) of separate inactivations of nuclear and mt cox2, suggesting that there is no selective advantage for a mt vs. nuclear location of cox2 in plants. The current distribution of cox2 presence and expression between the nucleus and mitochondrion in the studied legumes is probably the result of chance mutations silencing either cox2 gene.