五加科植物叶绿体基因组结构与进化分析

目的获取五加科叶绿体基因组的结构特征以及进化关系。方法以已测序完成的10个属的20种五加科植物叶绿体基因组为研究对象,系统比较基因组间的差异,分析4个IR边界扩张与收缩情况,并以近缘物种当归为外类群,使用MEGA 4.0构建系统进化树,分析物种间的亲缘关系。结果 20种五加科植物的叶绿体基因组大小差异较小,最大差仅1 909bp。各物种均出现基因替换现象,由cem A基因替换ycf10基因,且数量存在一定差异,主要由t RNA引起。通过比较发现,五加科物种的4个IR边界比较保守,仅野三七、三七和穗序鹅掌柴的边界基因进入IR区的长度与其他物种的差异较大。以当归为外类构建的系统进化树,各节点的支持率较高,清晰地反映了各物种间的亲缘关系。结论叶绿体基因组涵盖的信息量大,可以用于分析关系较近与进化较快物种的系统发生问题。

Analysis on structure and phylogeny of chloroplast genomes in Araliaceae species

Objective To obtain the structural characteristics and phylogentic relationships of the chloroplast genome in Araliaceae species. Methods we used 20 chloroplast genomes which have sequenced as materials, they were from 20 species belonging to 10 genus of Araliaceae. Analysis the differences of genomes and the dilation or shrink of four boundaries for IR, we used MEGA 4.0 to build the phylogenetic tree with Angelica gigas of sibling species as the outgroup and analysis their phylogentic relationships. Results There was a small difference among the chloroplast genomes size, and the largest difference is 1 909 bp. All of species had existed gene replacements, cemA replaced ycf10, and number of genes existed some differences, they were mainly caused by tRNA. The four boundaries of IR was relatively conservative, only Panax vietnamensi, Panax notoginseng and Schefflera delavayi were special, their boundary genes were in IR. All nodes of the phylogenetic tree of Araliaceae which was based on Angelica gigas were of high supports, and the tree had good resolution to reflect the genetic relationships among Araliaceae. Conclusion Chloroplast genomes have a lot of information, it can be used to analysis phylogeny among the species which are affinity or faster evolution.