中国石蒜属遗传多样性与亲缘关系的SSR分析

利用SSR-PCR分析中国石蒜属植物的遗传多样性与种间亲缘关系,从46对SSR引物选出18对扩增清晰、多态性好的引物对石蒜属15个种和外类群中国水仙进行了PCR扩增,采用非变性聚丙烯酰胺凝胶电泳和改良的银染法染色,结果表明供试材料具有高度的遗传多样性,多态性位点百分率达97.63%。通过UPGMA法将供试20份材料聚成4类。第I类包括安徽石蒜、长筒石蒜、黄长筒石蒜、忽地笑、中国石蒜、乳白石蒜,其中安徽石蒜与长筒石蒜的亲缘关系很近;第II类包括香石蒜、鹿葱、换锦花、红蓝石蒜和玫瑰石蒜;第III类由石蒜、矮小石蒜、稻草石蒜和江苏石蒜组成;第IV类为外类群中国水仙。分子聚类结果不仅支持乳白石蒜、鹿葱、红蓝石蒜、江苏石蒜、稻草石蒜的杂交起源观点,而且与形态学分类、物种的染色体倍性、核型存在较高的一致性,即除乳白石蒜外,染色体基数接近或等于11、核型含有11t或11t 倍数的物种聚为一大类;染色体基数不等于11、核型为6M+10T的种聚成了另一大类。SSR-PCR容易区分同种不同产地的安徽石蒜或不同花色的长筒石蒜,外形十分相似的石蒜和矮小石蒜,忽地笑和中国石蒜。本研究认为,将安徽石蒜作为一个独立的种不太合适,它可能是长筒石蒜的变种或是以长筒石蒜为亲本的杂交种。     

基于叶绿体DNA atpB-rbcL区序列探讨石蒜属种间系统发育关系

摘要：为了探讨石蒜属（Lycoris Herb.）的种间系统发育关系,对石蒜属95个材料包括15种、4变种及2个人工杂种的叶绿体 DNA atpB-rbcL间隔区进行了测序,结合花部形态和核型特征,探讨了石蒜属种间系统关系及其可能的杂交起源,结果表明：在系统发育树上亲缘关系近的材料聚在一起,其中矮小石蒜（L. radiata var. pumila）和换锦花（L. sprengeri）与2个人工杂交种（Hybrid 1、Hybrid 2）、麦秆石蒜（L. straminea）、江苏石蒜（L. houdyshelii）、短蕊石蒜（L. caldwellii）和乳白石蒜（L. albiflora）具有密切的亲缘关系。atpB-rbcL序列揭示的石蒜属种间关系与染色体核型的分类结果部分一致,主要表现在具有近端部着丝粒(A)染色体的种与具有中部(M)和端部(T)着丝粒染色体的种各成一支,与形态和染色体分类结果一致;不同之处在于具有中部、端部和近端部着丝粒染色体的种分散在两个主要分支内,进一步验证了具有中部、端部和近端部3种着丝粒类型染色体组的石蒜如麦秆石蒜、江苏石蒜、短蕊石蒜和乳白石蒜等是杂交起源的假设,结合2个人工杂交种分析,揭示了短蕊石蒜和乳白石蒜的近端部着丝粒染色体来源于换锦花;麦秆石蒜和江苏石蒜近端部着丝粒染色体来源于矮小石蒜。     

应用HPLC图谱进行石蒜属种间关系与分类研究

利用高效液相色谱(HPLC)对石蒜属及其近缘植物中国水仙共17份样品的生物碱进行检测,以各样品生物碱色谱峰的相对保留时间为变量,采用SPSS12.0中的Q型聚类法,得到树形图。聚类分析结果显示,17份样品聚成3类:第Ⅰ类包括长筒石蒜、安徽石蒜、鹿葱、换锦花、中国石蒜、香石蒜、乳白石蒜、红蓝石蒜8个种;第Ⅱ类由石蒜、稻草石蒜、江苏石蒜、忽地笑、玫瑰石蒜、矮小石蒜组成;中国水仙单独成第Ⅲ类。聚类结果与传统分类结果有较好的一致性,并支持鹿葱、玫瑰石蒜、安徽石蒜杂交起源的观点。外形相似的忽地笑与中国石蒜,矮小石蒜与石蒜HPLC图谱明显有别,表现出较远化学亲缘关系。表明HPLC化学图谱可用于石蒜属及其近缘植物中国水仙的分类和鉴别研究,并为石蒜属植物指纹图谱研究和质量控制提供重要参考。     

乳白石蒜rDNA-ITS序列分析及种内系统发育研究

对来源于不同产地的11个乳白石蒜(Lycoris albiflora Koidz.)种源的rDNA-ITS序列进行了扩增、纯化、克隆、酶切和测序,并对各种源的rDNA-ITS序列长度、G+C含量、碱基差异和遗传距离进行了比较分析,构建了系统发育树.结果表明,乳白石蒜11个种源的rDNA-ITS序列具有较高的同源性,但不同种源间的ITS序列长度和碱基变异较大;乳白石蒜rDNA-ITS序列总长度约为700 bp,共有318个变异位点;ITS1、ITS2和5.8S rDNA片段长度分别为222～245、240～252和163 bp;ITS序列中的G+C含量均明显高于A+T含量,ITS1和ITS2片段中的G+C含量分别为53.8%～70.5%和63.4%～73.4%;碱基变异类型多为颠换、转换、插入和缺失.种源间的遗传距离差异较大,其中浙江天目山种源(TM3)与浙江宁波种源(NB2)的遗传距离最小(0.000),其他种源间遗传距离为0.067～0.323.基于ITS序列分析结果可将11个乳白石蒜种源聚为3大类,第1类包括采自浙江天目山(TM1和TM2)和浙江宁波(NB3)的3个种源,花和花丝多为白色;第2类包含来源于不同产地的7个种源,花多为乳白色或乳黄色;第3类仅有采自浙江兰溪(LX)的1个种源,花色变异较大.研究结果表明,乳白石蒜种内有丰富的遗传变异,种源间的ITS序列差异与花的特征变化一致,但与地理分布并不相关;rDNA-ITS序列分析可用于乳白石蒜的亲缘关系、物种鉴别和遗传多样性研究.     

石蒜属植物分支系统学分析

基于37个形态学、解剖学、孢粉学和细胞学性状及解剖学性状之外的28个形态学、孢粉学和细胞学性状,分别对石蒜属进行分支系统学分析,试图建立石蒜属种间的系统发育关系。利用PAUP^*软件分别构建了最大简约树(MP),所得树的拓扑结构是一致的。同时,基于解剖学9个性状,对石蒜、换锦花、忽地笑、江苏石蒜、长筒石蒜、乳白石蒜、夏水仙、红兰石蒜、安徽石蒜、短蕊石蒜、中国石蒜11个种进行系统发育树构建,其结果也是支持上述系统发育树的。系统发育树结构结果表明,石蒜属16种明显聚为两大类:石蒜、玫瑰石蒜、稻草石蒜和江苏石蒜;广西石蒜、红兰石蒜、换锦花、香石蒜、夏水仙、长筒石蒜、安徽石蒜、中国石蒜、忽地笑、乳白石蒜、短蕊石蒜和陕西石蒜。除换锦花、红兰石蒜及江苏石蒜系统发育位置不同之外,大类群的划分与RAPD指纹图谱基本一致。类群一均属于石蒜亚属(Lycoris亚属)。类群二又可以聚为两小类:广西石蒜、红兰石蒜、换锦花、香石蒜、夏水仙归为一类;长筒石蒜、安徽石蒜、中国石蒜、忽地笑、乳白石蒜、短蕊石蒜和陕西石蒜归为一类。前一子类群除广西石蒜外,都属于整齐花亚属(Symman thus亚属)。后一子类群除长筒石蒜与安徽石蒜外,均属于石蒜亚属(Lycoris亚属)。因此,花冠整齐与否是一个重要的分类特征,但作为石蒜属植物亚属的划分依据,没有得到本研究支持。而在本文中,雄蕊与花被片的位置关系可以作为大分类群划分依据,能否依此来对石蒜属植物亚属进行划分,仍需探讨。另外研究表明叶微形态特征在研究种间亲缘关系时,具有一定的作用。而在种间亲缘关系鉴定时,出叶期不应成为重要的依据。同时研究还表明中国石蒜与忽地笑具有非常近的亲缘关系,与形态学研究一致。     

石蒜属植物多糖组成的分析比较研究

对五种石蒜属植物:安徽石蒜、中国石蒜、忽地笑、换锦花、石蒜多糖的结构组成进行了对比分析。结果表明,安徽石蒜多糖与其他四种植物多糖差异较大,而忽地笑多糖和石蒜多糖相似、中国石蒜多糖和换锦花多糖相似。该研究为探讨石蒜属种间亲缘关系提供实验依据。     

石蒜属植物多糖的分离纯化

对五种石蒜属植物,安徽石蒜、中国石蒜、忽地笑、换锦花、石蒜多糖的提取、分离、纯化及其理化性质进行了研究。为石蒜属植物多糖开发利用提供依据,更为相关石蒜属植物多糖的最佳提纯过程和探讨该属种间亲缘关系提供资料。     

中国原产石蒜属植物的数量分类和主成分分析

应用数量分类学方法对中国原产石蒜属13种2变种的35个性状进行Q、R聚类分析和主成分分析,探讨国产石蒜属植物种间的亲缘关系,并对分类性状进行评价。研究结果显示,Q型聚类可分为2个大类和8小类,安徽石蒜与长筒石蒜的亲缘关系很近,认为将其作为长筒石蒜的变种更为合适,同时支持玫瑰石蒜、红蓝石蒜、乳白石蒜、江苏石蒜、稻草石蒜的杂交起源观点。R型聚类可分为7个组;经主成分分析,35个性状可综合为5个主成分,其累积贡献率达82.55%,根据这5个主成分与性状间的相关性,选出影响比较大的16个性状,其中鳞茎形状、花被片宽和雄蕊长/花被片长的比值最为重要,可作为大类群划分的依据,而花被片是否具条纹、花丝颜色、花色、花葶粗、幼叶尖端及边缘颜色、种子有无等可作为物种划分的重要依据。     

枇杷属内栽培种和部分野生种ITS序列分析

对不同栽培区的25种普通枇杷品种以及7种枇杷属野生种的ITS序列进行扩增并测序,采用邻接法和最大简约法进行系统发育树的构建并对枇杷属内不同种间的遗传关系进行了分析。结果表明:枇杷属植物ITS序列ITS1+5.8S rDNA+ITS2总长度为592 bp或594 bp,长度变化发生在ITS2。所有样本的ITS1和5.8S rDNA长度一样,都是223 bp和168 bp;而ITS2为201 bp或203 bp。5种枇杷属野生种的ITS序列长度为594 bp,包括栎叶枇杷、大渡河枇杷、南亚枇杷、南亚枇杷窄叶变种和大瑶山枇杷;其余2种枇杷属野生种(麻栗坡枇杷、小叶枇杷)和普通枇杷栽培种的ITS序列长度都为592 bp。所有样本ITS序列的GC含量为64.2%~64.5%,其中ITS1为64.1%~65.5%,ITS2为68.1%~72.6%。对所有样本的ITS序列比对产生44个可变位点,其中38个为简约信息位点,其中11个位于ITS1,5个位于5.8S rDNA,22个位于ITS2。最大的种间序列差异为7.7%,最小的种间差异发生在麻栗坡枇杷和小叶枇杷之间,仅为0.2%。普通枇杷种内的ITS序列差异很低,25种普通枇杷栽培种之间的序列差异为0~1.5%。所研究的枇杷属植物可分为3个分支。分支Ⅰ包括所有普通枇杷品种,分支Ⅱ包含5种野生枇杷种,包括栎叶枇杷、大渡河枇杷、南亚枇杷、南亚枇杷窄叶变种和大瑶山枇杷;分支Ⅲ由2个野生枇杷种(麻栗坡枇杷、小叶枇杷)组成。该研究结果表明ITS序列对枇杷种间鉴定和系统发育分析具有一定意义,但对普通枇杷栽培种间的鉴定作用不大。     

基于ITS 序列探讨沙棘属植物的系统发育关系

对分布于青海境内的中国沙棘、肋果沙棘和西藏沙棘的ITS区进行扩增和序列分析,并以胡颓子科胡颓子属沙枣为外类群,对胡颓子科沙棘属15种植物的ITS序列进行聚类分析, 探讨沙棘属各植物的亲缘关系.结果表明： 3种沙棘属植物的ITS区长度为600～605 bp,其中,ITS-1区为201～203 bp,5.8S为166～167 bp,ITS-2区为232～236 bp.核苷酸分析显示,3种沙棘属植物的ITS区存在丰富的变异位点.聚类分析表明,棱果沙棘种的2个亚种——棱果沙棘和理塘沙棘为2个不同种,江孜沙棘与柳叶沙棘之间的亲缘关系较近,而与中国沙棘亲缘关系较远;沙棘种下9个亚种间的聚类结果与形态学分类差异较大.
     

ITS-2 secondary structures and phylogeny of Anopheles culicifacies species

Background: Second internal transcribed spacer (ITS2) has proven to contain useful biological information at higher taxonomic levels. Objectives: This study was carried out to unravel the biological information in the ITS2 region of An. culicifacies and the internal relationships between the five species of Anopheles culicifacies. Methodology: In achieving these objectives, twenty two ITS2 sequences (~370bp) of An. culicifacies species were retrieved from GenBank and secondary structures were generated. For the refinement of the primary structures, i.e. nucleotide sequence of ITS2 sequences, generated secondary structures were used. The improved ITS2 primary structures sequences were then aligned and used for the construction of phylogenetic trees. Results and discussions: ITS2 secondary structures of culicifacies closely resembled near universal eukaryotes secondary structure and had three helices, and the structures of helix II and distal region of helix III of ITS2 of An. culicifacies were strikingly similar to those regions of other organisms strengthening possible involvement of these regions in rRNA biogenesis. Phylogenetic analysis of improved ITS2 sequences revealed two main clades one representing sibling B, C and E and A and D in the other. Conclusions: Near sequence identity of ITS2 regions of the members in a particular clade indicate that this region is undergoing parallel evolution to perform clade specific RNA biogenesis. The divergence of certain isolates of An. culicifacies from main clades in phylogenetic analyses suggests the possible existence of camouflaged sub-species within the complex of culicifacies. Using the fixed nucleotide differences, we estimate that these two clades have diverged nearly 3.3 million years ago, while the sibling species in clade 2 are under less evolutionary pressure, which may have evolved much later than the members in clade 1.     

Genetic variations in the chloroplast genome and phylogenetic clustering of Lycoris species

The genus Lycoris of Amaryllidaceae comprises approximately 20 species that are distributed only in the moist warm temperate woodlands of eastern Asia. The objectives of this study were: (1) to clarify the phylogeny of the Lycoris species by using the definitive DNA sequencing method and (2) to examine the possible maternal donor of the hybrid origin Lycoris species and the Japanese triploid strains of Lycoris radiata var. radiata. The nucleotide sequence of the maturase K (matK) gene and the noncoding intergenic spacer (IGS) between the atpB and rbcL genes in the chloroplast genome were determined in a total of 27 strains of 11 species of the genus Lycoris. Variation among taxa was mainly due to nucleotide substitution, although deletions and an insertion were found in the IGS. For two chloroplast regions, the phylogenetic trees showed essentially similar topology, indicating the existence of four clades, I, II, III, and IV. For all the species except L. radiata, intraspecific variation was smaller than interspecific variation. For L. radiata, triploid strains were divided into clades I and II, and diploid strains were divided into clades I and IV. This implies that the diploid species of L. radiata var. pumila is a probable ancestral species. The clustering indicated that the chloroplast genome has not evolved in parallel with the karyotype in genus Lycoris. Regarding the hybrid origin species, the maternal parents of L. squamigara, L. albiflora and L. rosea were revealed to be L. longituba, L. radiata and L. radiata var pumila, respectively. We also suggest that a diploid strain of L. radiata var. pumila in clade I might be a candidate of the maternal donor of the Japanese triploid strains. A possible model of the maternal donor of Lycoris species is proposed.     

根据ITS序列证据重建防己科蝙蝠葛族的系统发育

研究了国产防己科蝙蝠葛族tirb．Menispermeae9属20种和外类群青牛胆族trib．Tinosporeae 2属3种植物完整的ITS(包括5.8S rDNA)序列。trib．Menispermeae的ITS长527～601 bp,排序后长667bp。当gap处理为missing时具281个有信息位点。PAUP软件分析结果表明：①trib．Menispermeae是一个单系类群,该分支得到hootstrap l00％的支持;②确定了存疑种Pachygone valida的系统学位置,该种是Coc—culus属的成员;③Sinomenium和Menispermum两属有很近的系统学关系,组成族内稳定的一支,它们的ITS序列同源性极高,ITS1比族内其它属长41～73bp;④Stephania和Cyclea也是系统发育关系很近的两个类群。前者具两个主要分支,其IIS1、ITS2的G+C含量差异较大,在种类组成上,该两大支与传统上Stephania属内处理的2个亚属——千金藤亚属subgen．Stephania和山乌龟亚属subgen．Tuberiphania基本一致;Cyclea属内种间的ITS序列差异小,同源性极高。     

Sequence analysis of the ribosomal DNA internal transcribed spacer region in some scallop species (Mollusca: Bivalvia: Pectinidae).

The internal transcribed spacer (ITS) region of the ribosomal DNA from the European scallops Aequipecten opercularis, Mimachlamys varia, Hinnites distortus, and Pecten maximus was PCR amplified and sequenced. For each species, three or five clones were examined. The size ranged between 636 and 713 bp (ITS1, 209-276 bp; 5.8S rRNA gene, 157 bp; ITS2, 270-294 bp) and GC content ranged between 47 and 50% (ITS1, 43-49%; 5.8S rRNA gene, 56-57%; ITS2, 44-49%). Variation within repeats was minimal; only clones from M. varia and P. maximus displayed a few variable sites in ITS2. Among scallops, including Chlamys farreri whose ITS sequence appears in databases, significant variation was observed in both ITS1 and ITS2. Phylogenetic analysis using ITS1, ITS2, or both spacer sequences always yielded trees with similar topology. Aequipecten opercularis and P. maximus grouped in one clade and the other three scallops (C. farreri, M. varia, and H. distortus) in another, where M. varia and H. distortus are the more closely related species. These results provide new insights into the evolutionary relationships of scallop species and corroborate the close evolutionary relationship between the tribes Aequipectinini and Pectinini previously deduced from 18S rDNA sequences.     

帘蛤科贝类rDNA内转录间隔区序列的研究

根据18SrDNA、5．8SrDNA和28SrDNA保守序列设计引物,应用聚合酶链式反应（PCR）扩增了文蛤（Meretrix meretrix L．）、青蛤（Cyclina sinensis G）、硬壳蛤（Mercenaria mercenaria L．）和江户布目蛤（Protothaca jedoensis L．）4种帘蛤科贝类的第一内转录间隔区（ITS1）和第二内转录间隔区（ITS2）序列,并进行了测序。结果表明,文蛤、青蛤、硬壳蛤和江户布目蛤的ITS1扩增产物大小分别为978bp、663bp、757bp和942bp,GC含量分别为61．55％、60．78％、62．48％和64．86％～64．97％,其中ITS1序列长度分别为900bp、585bp、679bp和864bp,是迄今已报道双壳贝类中变化范围最大的,GC含量分别为61．67％、61．03％、63．03％和65．51％～65．62％,江户布目蛤种内ITS1序列有个体差异;ITS2扩增产物大小分别为644bp、618～620bp、593bp和513～514bp,GC含量分别为61．18％、61．29％～61．81％、62．73％和61．48％61．60％,其中ITS2序列长度分别为412bp、386～388bp、361bp和281～282bp,GC含量分别为65．29％、65．21％～66．06％、67．87％和67．38％～67．62％,青蛤和江户布目蛤种内ITS2序列有个体差异。4种蛤ITS1和ITS2序列种间差异很大,有明显的长度多态性,ITS2种间序列相似度73．0％～89．1％,与ITS1的种间序列相似度48．7％～81．5％相比略高。此外,在4种蛤ITS1和ITS2序列中各发现2个与rRNA加工有关的保守区。通过对ITS1和ITS2序列的组装获得了4种蛤5．8SrRNA基因完整序列,序列长度都是157bp,GC含量57．96％～58．60％,4种蛤5．8SrRNA基因相对保守,种间序列差异度0-6．0％,共有10个变异位点,其中转换4处,颠换6处,硬壳蛤和江户布目蛤5．8SrRNA基因序列完全相同。以ITS2序列（包含5．8SrRNA和28SrRNA基因部分序列）为标记,调用北极蛤科的Arctica islandica相应序列数据作外群,构建了帘蛤科贝类的系统发育树,其拓扑结构显示江户布目蛤与硬壳蛤亲缘关系最近,青蛤与其他3物种的亲缘关系最远。     

用ITS序列研究杨属各组之间的系统发育关系

杨树是重要的工业用材树种。我国杨树遗传资源丰富 ,分布范围广泛 ,不少种为我国特有。开展杨属系统发育和分子进化研究 ,对丰富的杨树遗传资源保存和利用有着重大意义。杨属 (Ｐｏｐｕｌｕｓ)全世界约 10 0余种 ,属下通常分 5个组[1] 。胡志昂等[2 ] 对杨属不同组间的过氧化物酶同工酶进行了研究 ;李宽钰等[3] 利用ＲＡＰＤ标记技术对白杨组、青杨组、黑杨组 2 0个种作了遗传分析。但是在杨属系统分类上还存在着许多混乱 ,同物异名、同名异物现象相当普遍。本文以杨属 5个派主要代表种为材料 ,用ＰＣＲ产物直接测序法测定杨树ＩＴＳ序列 ,…     

EVOLUTION OF MACROCYSTIS SPP. (PHAEOPHYCEAE) AS DETERMINED BY ITS1 AND ITS2 SEQUENCES1,

Macrocystis (Lessoniaceae) displays an antitropical distribution, occurring in temperate subtidal regions along western North America in the northern hemisphere and throughout the southern hemisphere. We used the noncoding rDNA internal transcribed spacer regions (ITS1 and ITS2) to examine relatedness among (1) Macrocystis and several genera of Laminariales, (2) four species of Macrocystis ( M. integrifolia Bory from the northern hemisphere, M. angustifolia Bory and M. laevis Hay from the southern hemisphere, and M. pyrifera [L.] C. Ag. from both hemispheres), and (3) multiple clones of several individuals. Of the taxa included in our phylogenetic analysis, the elk kelp, Pelagophycus porra (Lem.) Setch., was the sister taxon to Macrocystis spp. Macrocystis individuals from the southern hemisphere (representing three species) formed a strongly to moderately supported clade, respectively, when the ITS1 and ITS2 sequences were analyzed separately. No distinction was detected between the two species in the northern hemisphere. Thus, Macrocystis may be a monospecific genus ( M. pyrifera ). A northern-hemisphere-to-southern-hemisphere pattern of dispersal was inferred, because northern-hemisphere individuals were more diverse and displayed paraphyletic clades, whereas southern-hemisphere individuals were less diverse and formed a monophyletic clade. High intraindividual variation in ITS1 sequences was observed in one individual from Santa Catalina Island (CA), suggesting very recent and rapid mixing of genotypes from areas to the north and Baja California (Mexico) or introgressive hybridization with Pelagophycus.     

ITS1 and ITS2 Sequences of Four Possible Donors to Bread Wheat Genome and Their Phylogenetic Relationships

The 1TS1 and ITS2 of rDNA of four diploid species, newly Triticum urartu Thum. (AA), T. monococcum var. boeoticum (Boiss.) MK (AA),Aegilops speltoides Tausch. (BB) and Ae. taus&ii Coss. (DD), the most possible donors of A, B and D genomes to broad wheat ( T. aestivum), were amplified by PCR, cloned and sequenced. Some published sequences were discussed and rectified. The length of ITS1 sequences in four species was 221 to 223 bp, and that of 1TS2 was 216 to 217 bp. In pairwise sequence comparisons among four species, divergence ranged from 0.029 0 to 0.064 0 in ITS1, and from 0.009 3 to 0.058 0 in ITS2. Based on ITS1, ITS2 and 1TS1 + ITS2 data respectively, the same most parsimony tree that is congruent with the phylogenetic relationships was generated which was concordant with their morphological and cytological characteristics. In the trees, T. urartu and T. monococcum var. boeoticum constituted one monophyly, whereas two species of the genus Aegilops, Ac. speltoides and Ac. tauschii, fortmed another mono- phyly but with lower bootstrap value than the first clade. This study suggests that ITS region is a useful molecular marker in the studies on the origin and evolution of Triticum.     

用ITS序列研究杨属各组之间的系统发育关系

ITS sequences of 15 representative species of five sections inthe genus Populus L. were determined. By using direct sequencing of PCR product, it was found that the fragments of internal transcribed spacers (ITS) are about 594 bp in length. The length of ITS-1 and ITS-2 is about 220 bp and 210 bp, respectively, while that of 5.8s is 164 bp. Its G+C content is about 69.0%. The number of phylogenetically informative loci is higher in ITS-2 than in ITS-1. Transversion and transition are two main factors that drive the ITS evolution, and more insertions and deletions occurred in ITS-2. Taking Salix matsudana Koidz. and Salix suchowensis Cheng as outgroups, phylogenetic analysis of ITS sequences using PAUP 4.0 software indicated that Populus is monophyletic group and can be divided into two main clades. One is the section Leuce, and the other is the remaining sections.