To reveal the evolution and molecular characteristics of miR172 family members,161 pre-miR172 precursors and 196 miR172s in 37 species registered in miRbase (version 21.0) were used to construct the phylogenetic tree and to predict the secondary structure,the target genes and the motifs.The results showed that the miR172 family members existed in 37 species,and all of which belonged to the angiosperm plants,and therefore the angiosperm might be the evolutionary ancestors of the miR172 family in plants.The conservation of sequences was a major factor to affect the clustering results of miR172 family,and the next was the species specificity.The sequences of miR172-5p members were more specific than those of miR172-3p members.Mfold predicted that pre-miR172 spontaneously formed a typical,stable stem-loop secondary structure,and the stem sequences were more conserved than the loop sequences.The pre-miR172 had only one UNCG tetraloop motif.Target gene analysis showed different miR172 members from the same species and different species might have different target genes,among of which the frequencies of AP2 or AP2-like were the highest,and others included arginine decarboxylase 1,pathogenesis-related,MYB84 and so on,which showed diversity of target functions.%为了解植物miR172家族成员的进化与分子特性,对miRbase数据库中37个物种的161个miR172前体序列和196个miR172成熟体序列进行进化规律分析,并对植物miR172家族的保守基序、二级结构和靶基因进行预测分析.结果表明:miR172家族成员分布的37个物种都是被子植物,被子植物很可能是miR172家族进化来源的祖先.进化分析表明,植物miR172家族成员序列相似性是其聚类的首要影响因素,其次才是物种差异的影响.植物miR172家族成员成熟体序列分析表明,5p臂上形成的成熟体序列特异性较大,3p臂上形成的成熟体序列保守性较高.二级结构分析发现,植物miR172家族成员具有典型的茎环二级结构,且茎序列的保守性较环序列高.植物miR172前体序列包含1个UNCG环.靶基因预测分析发现,同一物种不同miR172成员的靶基因可能不同;不同物种miR172的靶基因也可能不同,AP2或AP2-like出现频率最高,其次还有arginine decarboxylase 1、Pathogenesis-related、MYB84等靶基因,表明其靶基因功能的多样性.
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