核果类果树ITS序列分子进化及系统发育关系研究

Molecular Evolution and Phylogeny of Stone Fruit Trees Based on Sequences of the Internal Transcribed Spacers (ITS) of Nuclear Ribosomal DNA

为研究核果类果树的进化和系统发育,选择桃、李、梅、杏、樱桃各2～4个主要种或变种共16个基因型测定其ITS序列,与从GenBank下载的6个核果类果树ITS序列形成了较为全面的数据矩阵。采用二次置根法用樱桃置根,用PAUP软件计算数据集在56个进化模型的得分,Modeltest筛选最佳模型和参数,计算遗传距离、变异,用最大简约法构建了桃、李、梅、杏、樱桃的系统发育树。结果表明:1.核果类果树各组ITS1和ITS2的分子进化速率不同,信息量也不同;2.核果类果树演化顺序为:共同的原始材料分化成樱桃、李、杏,再由李进化产生桃,杏进化产生梅;3.辽杏较普通杏和西伯利亚杏原始,桃演化顺序是:巴旦杏—山桃—普通桃、新疆桃;4.本结果支持将核果类果树分成4个亚属。

To analyze the molecular evolution and phylogeny of stone fruit trees,the internal transcribed spacers（ITS）of nuclear ribosomal DNA isolated from 16 genotypes of peach（Prunus persica）,plum（P.salicina）,apricot（P.armeniaca）,mei（Prunus mume）,and cherry（Prunus avium）,2–4 genotypes per species,were sequenced.All these ITS sequences together with other 6 ones downloaded from the GenBank were analyzed using the second way of rooting with cherry used as the root.The broad data set was tested with 56 evolution models by PAUP 4.08b software,and the scores were used to screen the best model and parameters with Modeltest 3.7 software.Mega 3.1 software was used to calculate genetic distance and variance among the genotypes and to construct maximum parsimony phylogenetic tree.The result indicated：Molecular evolution rates of ITS1 and ITS2 among the stone fruit trees were different,same did the information of them;the evolution order of 5 stone fruit trees was that cherry,plum,and apricot originated from same one ancestry plant,and then plum evolved to peach and apricot to mei;Prunus mandshurica is more original than P.sibirica and P.armeniaca;the evolution order in Prunus persica is from P.andersonii to P.davidiana and then to P.persica,P.ferganensis.It is reasonable that stone fruit trees are divided into 4 subgenera.