基于ITS序列的新疆野苹果系统发育及遗传多样性分析

Analysis of Phylogeny and Genetic Diversity of Malus sieversii(Ledeb.)M.Roem.Based on ITS Sequence

本研究以新疆野苹果的三个主要自然居群(新源、霍城和巩留)的90份种质资源为试材,利用ITS序列构建系统发育树,并进行遗传多样性分析。结果显示,供试样品的ITS序列对位后长度为603 bp,检测到变异位点272个,单一突变位点114个,简约信息位点158个,转换/颠换比率(R)为0.56。基于ITS序列的NJ树中,90份新疆野苹果和外类群基本分成了三个大分支。各居群的新疆野苹果相互交融,且自展支持率较低。90份新疆野苹果被分为了32个单倍型(Hd=0.9263,Pi=0.02966),巩留居群的遗传多样性最为丰富(h=17,Hd=0.95400,Pi=0.02336),其次是新源居群(h=16,Hd=0.94000,Pi=0.04070),最后是霍城居群(h=1)。巩留与新源的亲缘关系最近,新源与霍城的亲缘关系最远。基于ITS的Tajima′s D值为-2.33594,在P<0.01水平上极显著,不遵循中性进化模型,新疆野苹果遗传变异主要来自于自然选择。三个自然居群的新疆野苹果系统演化按照先巩留、新源后霍城的次序发生,居群间的遗传距离与地理距离相关。本研究旨在为新疆野苹果的系统发育及遗传多样性研究提供参考依据。

A total of 90 Malus sieversii(Ledeb.)M.Roem.germplasm resources from the three natural populations(Xinyuan,Huocheng and Gongliu)were used as experimental materials,and DNA extraction,nrDNAITS sequence fragment sequencing analysis were performed.In addition,the construction of the NJ phylogenetic tree and the calculation of genetic distance,haplotype analysis and Tajima’s D value were carried out.The results showed that the length of the ITS sequence of the test sample was 603 bp after alignment.A total of 272 mutation sites were detected,including 114 singleton sites and 158 parsimony information sites.The conversion/transversion ratio(R)was 0.56.In the NJ tree based on the ITS sequence,these 90 Malus sieversii(Ledeb.)M.Roem.and outer groups are basically divided into three major branches.These Malus sieversii(Ledeb.)M.Roem.of the various populations blended with each other,and the bootstrap value was low.These 90 Malus sieversii(Ledeb.)M.Roem.were divided into 32 haplotypes(Hd=0.9263,Pi=0.02966).The genetic diversity of the Gongliu population was the most abundant(h=17,Hd=0.95400,Pi=0.02336),followed by the Xinyuan population(h=16,Hd=0.94000,Pi=0.04070),and the Huocheng population(h=1)ranked last.The genetic relationship between Gong Liu and Xinyuan is the closest,and the genetic relationship between Xinyuan and Huocheng is the furthest.The Tajima’s D value based on ITS is-2.33594,it is extremely significant at the P<0.01 level,and does not follow the neutral evolution model.The genetic variation of Malus sieversii(Ledeb.)M.Roem.Mainly comes from natural selection.The systematic evolution of Malus sieversii(Ledeb.)M.Roem.in the three natural populations occurred in the order of Gongliu and Xinyuan,then Huocheng,and the genetic distance between populations was related to geographic distance.This research aims to provide reference basis for the study of phylogeny and genetic diversity of Malus sieversii(Ledeb.)M.Roem..