EVOLUTION OF A NONCODING REGION OF THE CHLOROPLAST GENOME
EVOLUTION OF A NONCODING REGION OF THE CHLOROPLAST GENOME
复制标题
DOI：
10.1006/mpev.1993.1006
复制
发表时间：
1993-03-01
影响因子：
4.1
通讯作者：
MA, DP
中科院分区：
文献类型：
--
作者：
GOLENBERG, EM;CLEGG, MT;MA, DP
通过比较叶绿体基因组中在基因rbc1和β之间映射的非编码部分的完整dna序列数据，研究核苷酸替换相对于插入/缺失事件的相对出现率。序列数据来自代表草科三个部落的九个物种。INDELs可以根据哪些是相邻或近端序列的缺失或复制，以及那些似乎不是相邻序列的排列来分类。第一类占记录的INDELs的82%。这些插入片段的特征还可以是通常在AS或TS的游程内的一个到几个碱基的直接复制，或者是更复杂序列的复制或缺失。当从一组密切相关的类群中观察时，插入事件的发生速度似乎与核苷酸替换事件相同或略快。然而，在亲缘关系较远的物种中，Indels的表观积累速度明显慢于核苷酸替换的速度。插入事件和核苷酸替换之间的表观累积速率的差异表明，在所有插入事件中重叠变化的比例高于在所有核苷酸替换事件中的比例。事实上，涉及更复杂序列的INDELs被发现局限于跨分类群的一些高度不稳定的位置。虽然相似，但独立的插入事件发生在不相关的分类群中的相同位置，但可能不在相关的分类群中共享，从而导致一种类型的分子平行。因此，基于Indel事件的系统发育树代表了一种与公认的这些禾本科植物的系统发育不一致的进化假说。基于核苷酸替换的系统发育树与公认的系统发育树是一致的。
The relative rate of occurrence of nucleotide substitutions versus indel (insertion/deletion) events is investigated by comparing complete DNA sequence data from the noncoding portion of the chloroplast genome that maps between the genesrbcL andatpβ. The sequence data are obtained from nine species that represent three tribes of the grass family. Indels could he categorized by those that are deletions or duplications of adjacent or proximal sequences and those that do not appear to be permutations of adjacent sequences. The first category represents 82% of the recorded indels. These indels may also be characterized by being direct duplications of one to several bases usually within runs of As or Ts or by being duplications or deletions of more complex sequences. When viewed from within groups of closely related taxa, indel events appear to occur at an equal or slightly faster rate than do nucleotide substitution events. However, the apparent rate of accumulation of indels in more distantly related species is significantly slower than that of nucleotide substitutions. This difference in apparent accumulation rates between indel events and nucleotide substitutions suggests that the proportion of superimposed changes has been higher among all indel events than among all nucleotide substitution events. Indeed the indels involving more complex sequences were found to be confined across taxa to a number of highly labile sites. Independent, though similar, indel events occur at identical sites in unrelated taxa, yet may not be shared among related taxa, resulting in a type of molecular parallelism. As a result, the phylogenetic tree based on indel events represents an evolutionary hypothesis which is inconsistent with the accepted phylogeny of these grasses. The phylogenetic tree based on nucleotide substitutions is consistent with accepted phylogeny.