Evolution of the mitochondrial rps3 intron in perennial and annual angiosperms and homology to nad5 intron 1
Evolution of the mitochondrial rps3 intron in perennial and annual angiosperms and homology to nad5 intron 1
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DOI：
10.1093/oxfordjournals.molbev.a026126
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发表时间：
1999-04-01
影响因子：
10.7
通讯作者：
Bousquet, J
中科院分区：
文献类型：
--
作者：
Laroche, J;Bousquet, J
对多年生和一年生植物10个属15个单子叶和双子叶被子植物的线粒体RPS3内含子的替换和插入速率变异进行了分析。总体而言，内含子序列在被子植物中非常保守。根据长度多态性，在10个属中鉴定出10个不同的等位基因。这些等位基因的差异主要归因于较大的Indels。在桦木科植物的乙醚谱系中，观察到在Alnus内含子中有133个核苷酸的插入，部分或完全缺失。该插入位于该组IIA内含子的二级结构模型的结构域IV内。在这个插入中发现了一个47个核苷酸的可移动元件，它与位于水稻RPS3内含子和基因间植物线粒体基因组中的序列具有同源性。桦木科序列的替换率和插入率都很低，但在涉及较远亲缘类群的比较中，替换率逐渐大于插入率。从二级结构模型来看，螺旋结构中涉及的区域与替换相比保存得很好，但在所分析的被子植物序列中没有观察到补偿性变化。利用基于化石记录的近似分化时间，观察到不同的一年生和多年生分类群对之间的替代和插入率的异质性。特别是，一年生矮牵牛和报春花的替代率和插入率分别比多年生桦树和赤杨快15倍和10倍以上。这是首次证明了多年生和一年生非编码DNA的进化速率差异，支持了中性原因，如世代时间、种群大小和物种形成率效应，以解释这种速率异质性。令人惊讶的是，RPS3内含子的序列与被子植物线粒体NAD5基因的内含子1序列有很高的同源性，这表明这两组IIA内含子是共同起源的。
The plant mitochondrial rps3 intron was analyzed for substitution and indel rate variation among 15 monocot and dicot angiosperms from 10 genera, including perennial and annual taxa. Overall, the intron sequence was very conserved among angiosperms. Based on length polymorphism, 10 different alleles were identified among the 10 genera. These allelic differences were mainly attributable to large indels. An insertion of 133 nucleotides, observed in the Alnus intron, was partially or completely absent in the ether lineages of the family Betulaceae. This insertion was located within domain IV of the secondary-structure model of this group IIA intron. A mobile element of 47 nucleotides that showed homology to sequences located in rice rps3 intron and in intergenic plant mitochondrial genomes was found within this insertion. Both substitution and indel rates were low among the Betulaceae sequences, but substitution rates were increasingly larger than indel rates in comparisons involving more distantly related taxa, From a secondary-structure model, regions involved in helical structures were shown to be well preserved from indels as compared to substitutions, but compensatory changes were not observed among the angiosperm sequences analyzed. Using approximate divergence times based on the fossil record, substitution and indel rate heterogeneity was observed between different pairs of annual and perennial taxa. In particular, the annual petunia and primrose evolved more than 15 and 10 times faster, for substitution and indel rates respectively, than the perennial birch and alder. This is the first demonstration of an evolutionary rate difference between perennial and annual forms in noncoding DNA, lending support to neutral causes such as the generation time, population size, and speciation rate effects to explain such rate heterogeneity. Surprisingly, the sequence from the rps3 intron had a high identity with the sequence of intron 1 from the angiosperm mitochondrial nad5 gene, suggesting a common origin of these two group IIA introns.