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序列的栓菌属部分种的分子分类初步研究

栓菌属 Trametes 的一些近缘种宏观和微观形态学非常相近,传统分类学方法难于对其进行准确分类定位。测定了 34 个分类单元的 ITS(包括 5.8SrDNA)序列,并对得到的 43 个分类单元的 ITS 序列进行系统发生分析,构建了聚类分析树状图。该树状图显示,栓菌属类群与其他属类群明显分开,Trametes versicolor 聚类到一个高支持率的独立分支。形态学上定名为 T. hirsuta 和 T. pubescens 物种聚类到同一高支持率的独立分支,试验分析表明这两个种应视为同一物种。     

应用ITS序列分析新疆濒危植物盐桦的系统发育

目的:依据ITS序列分析新疆濒危植物盐桦的系统发育.方法:运用PCR直接测序法,对珍稀濒危植物盐桦(Betulahalophila)的nrDNA的ITS区(包括ITS-1,5.8SrDNA和ITS-2)进行序列测定,并与GenBank中提取的17种桦木科桦木属植物的ITS区序列进行了组合分析.结果:盐桦的ITS序列和已公布的17种桦木科桦木属植物的ITS区序列差别不大,同源性在99.67%～99.01%之间.采用clustalx软件对盐桦和17种桦木属植物的ITS区序列进行系统发育分析,构建了桦木属植物的ITS分子系统树,18种桦木科桦木属植物形成三个分支,盐桦与Betula alnoides、Betula populifolia、Betula pubescens同为一支.结论:盐桦在桦木科桦木属内有独特的分类地位.     

睡莲科的系统发育:核糖体DNA ITS区序列证据

以金鱼藻Ceratophyllum demersum为外类群,使用PAUP4.0b4A软件对睡莲科Nymphaeaceae植物7属11个代表种的ITS区序列进行了系统发育分析。采用最大简约法分析获得了3个最简约树,步长为1125,一致性指数(CI)和维持性指数(RI)值分别为0.7618和0.7214。利用3个最简约树获取严格一致树。结果表明:(1)莲属Nelumbo位于系统树的基部,自展支持率为100%,可从睡莲科中独立出来成立莲科Nelumbonaceae和莲目Nelumbonales;(2)萍蓬草属Nuphar是一单系类群,位于分支Ⅱ的基部,并和睡莲科其他属(不包括莲属)植物聚在一起构成姐妹群,故萍蓬草属仍应置于睡莲科中;(3)水盾草属Cabomba和莼菜属Brasenia聚成一小支并构成姐妹群,自展支持率为99%,说明这两属之间亲缘关系较近;(4)睡莲属和芡实属Euryale、王莲属Victoria聚成一小支并构成姐妹群,自展支持率为94%,说明三者亲缘关系较近,仍应置于睡莲科中。     

基于nrDNAITS序列数据的兰属系统发育关系的初步分析(英)

现存的兰属分类系统是基于宏观形态学性状、尤其是花粉块的数目以及唇瓣与蕊柱的愈合程度而建立的。兰属因此而划分为 3个亚属 :兰亚属 (subgenusCymbidium) ,大花亚属 (subgenusCyperorchis)和建兰亚属 (subgenusJensoa)。本文运用PCR扩增和直接测序的方法分析兰属 (Cymbidium) 2 7种、3个栽培品种以及 3个外类群的核DNAITS区段序列。通过最简约性分析产生的ITS系统发育树表明 ,兰属的 3个亚属均可能为不自然的类群。大花亚属表现为一复系群 ,兰亚属的冬凤兰 (C .dayanum )隐藏于其中 ;建兰亚属为一并系群 ,它的成员之一兔耳兰(C .lancifolium)偏离出去而成为兰属一最基部的分支 ;兰亚属为一复系群 ,它分为几支而分别与另两个亚属组合在一起。由于兰属ITS序列位点变异率较低 ,最简约性分析产生的几支主要分支均得不到Bootstrap分析的高度支持 ,各亚属内组之间的关系也不明确。研究兰属的系统发育关系还需要新的数据。     

基于nrDNA ITS序列数据的兰属系统发育关系的初步分析

现存的兰属分类系统是基于宏观形态学性状、尤其是花粉块的数目以及唇瓣与蕊柱的愈合程度而建立的。兰属因此而划分为3个亚属：兰亚属（subgenus Cymbidium),大花亚属（subgenus Cyperorchis)和建兰亚属（subgenus Jensoa）。本文运用PCR扩增和直接测序的方法分析兰属（Cymbidium）27种、3个栽培品种以及3个外类群的核DNA ITS区段序列,通过最简约性分析产生的ITS系统发育树表明,兰属的3个亚属均可能为不自然的类群,大花亚属表现为一复系群,兰亚属的冬凤兰（C.dayanum）隐藏于基点;建兰亚属为一并系群,它的成员之一兔耳兰（C.lancifolium）偏离出去而成为兰属一最基部的分支;兰亚属为一复系群,它分为几支而分别与另两个亚属组合在一起,由于兰属ITS序列位点变异率较低,最简约性分析产生的几支主要分支均得不到Bootstrap分析的高度支持,各亚属内组之间的关系也不明确,研究兰属的系统发育关系还需要新的数据。     

中国水青冈属 （壳斗科） 叶结构及分类学意义

叶结构对壳斗科(Fagaceae)现存植物和化石的鉴定具有重要意义。通过对水青冈属5种植物叶结构特征进行细致的研究,结果发现水青冈属植物叶脉有羽状弓形脉、羽状半达缘脉两种类型;三级脉有波状对生贯穿、互生贯穿及混合贯穿三种类型;小脉缺失、简单无分支或一次分支;脉间区发育良好,网眼有三边形、四边形和五边形三种类型,排列规则;具齿种类叶齿由齿主脉和齿侧脉构成,齿侧脉环状。研究结果表明水青冈属二级脉与更高级脉序形成的结构稳定且存在种间差异,具重要分类学价值。基于水青冈属叶结构特征观察结果,本次研究编制了水青冈属植物的分种检索表;参照已有研究结果并结合重要外部形态学特征,编制了壳斗科相关类群分属检索表。     

中国水青冈属（壳斗科）叶结构及分类学意义

叶结构对壳斗科（Fagaeeae）现存植物和化石的鉴定具有重要意义。通过对水青冈属5种植物叶结构特征进行细致的研究,结果发现水青冈属植物叶脉有羽状弓形脉、羽状半达缘脉两种类型;三级脉有波状对生贯穿、互生贯穿及混合贯穿三种类型：小脉缺失、简单无分支或一次分支：脉间区发育良好,网眼有三边形、四边形和五边形三种类型,排列规则;具齿种类叶齿由齿主脉和齿侧脉构成,齿侧脉环状。研究结果表明水青冈属二级脉与更高级脉序形成的结构稳定且存在种问差异．具重要分类学价值。基于水青冈属叶结构特征观察结果,本次研究编制了水青冈属植物的分种检索表：参照已有研究结果并结合重要外部形态学特征,编制了壳斗科相关类群分属检索表。     

基于nrDNA ITS 序列数据的兰属系统发育关系的初步分析

现存的兰属分类系统是基于宏观形态学性状、尤其是花粉块的数目以及唇瓣与蕊柱的愈合程度而建立的.兰属因此而划分为3个亚属:兰亚属 (subgenus Cymbidium),大花亚属(subgenus Cyperorchis) 和建兰亚属 (subgenus Jensoa).本文运用PCR扩增和直接测序的方法分析兰属 (Cymbidium) 27种、3个栽培品种以及3个外类群的核DNA ITS 区段序列.通过最简约性分析产生的ITS系统发育树表明,兰属的3个亚属均可能为不自然的类群.大花亚属表现为一复系群,兰亚属的冬凤兰 (C.dayanum) 隐藏于其中;建兰亚属为一并系群,它的成员之一兔耳兰 (C.lancifolium) 偏离出去而成为兰属一最基部的分支;兰亚属为一复系群,它分为几支而分别与另两个亚属组合在一起.由于兰属ITS序列位点变异率较低,最简约性分析产生的几支主要分支均得不到Bootstrap分析的高度支持,各亚属内组之间的关系也不明确.研究兰属的系统发育关系还需要新的数据.     

虎耳草属山羊臭组的界定和系统发育: 核糖体DNA ITS序列证据

虎耳草属Saxifraga山羊臭组sect. Ciliatae是该属中最大的一个组, 共有175种, 主要分布在喜马拉雅地区, 我国分布有166种, 占总种数的95%; 其中, 112种为中国特有。约80%的种类分布在我国青藏高原和西南地区, 是中国喜马拉雅植物成分的代表类群。山羊臭组内物种分化十分显著, 分类处理也很困难, 该组是否为单系类群, 组下的系统发育关系也不清楚, 均需进一步验证。本文测定了虎耳草属山羊臭组及其他组33种植物样品的核糖体DNA内转录间隔区ITS序列, 并从GenBank调取虎耳草组sect. Saxifraga等组和近缘属唢呐草属Mitella共22种植物的该序列。ITS分析结果表明: (1)所研究的山羊臭组类群聚为单独一支, 而且与垫状组sect. Porphyrion、虎耳草组、球茎组sect. Mesogyne和仅在欧洲分布的sect. Cymbalaria和sect. Cotylea等8个组聚成的另一分支构成姊妹群; (2)根据形态特征建立的山羊臭组的3个亚组即唐古拉亚组subsect. Hirculoideae、莲座状亚组subsect. Rosulares和具芽亚组subsect. Gemmiparae各自聚为一支, 但是莲座状亚组这一支的支持率较低。同时, 山羊臭组的鞭匐枝亚组subsect. Flagellares和subsect. Hemisphaericae的代表类群单独聚为一支, 位于具芽亚组类群分支内部而不能成立; (3)唐古拉亚组和莲座状亚组又聚为一亚分支与具芽亚组构成姊妹群, 而且具芽亚组最早从山羊臭组这一支中分化出来。我们的研究还发现山羊臭组内种间形态分化较大, 而ITS碱基变异较小, 这可能是山羊臭组类群在青藏高原及毗邻地区的高山环境下物种快速分化的结果。     

Patterns of molecular and morphological differentiation in Fagus (Fagaceae): phylogenetic implications

To study phylogenetic relationships among species of Fagus, the internal transcribed spacer regions ITS1 and ITS2 of the nuclear ribosomal DNA and morphological data were analyzed. Both molecular and morphologically based phylogenies suggest that Eurasian species of Fagus subgenus Fagus are basal to the North American Fagus grandifolia. The subgenus Fagus is a paraphyletic group basal to three East Asian species forming the subgenus Engleriana. Due to a considerably large amount of DNA polymorphism, relationships among basal species of Fagus could not be entirely resolved when analyzing ITS sequences with standard methods. Morphological trees helped to resolve more clearly relationships within the subgenus Fagus. The East Asian F. hayatae is suggested to be basal to the rest of the genus. This hypothesis is further supported by distinctive patterns of nucleotide variability found for ITS regions, allowing for basic and derived types to be distinguished. The high degree of ITS polymorphism within Fagus can be explained by (1) the complex evolutionary behavior of this marker, (2) the stenoecious ecological characteristic of Fagus with respect to its continuous geographic range throughout much of the Cenozoic, and (3) the absence of major radiations into further habitats as occurred in other Fagaceae.     

Phylogenetic relationships among species of Hypochaeris (Asteraceae, Cichorieae) based on ITS, plastid trnL intron, trnL-F spacer, and matK sequences

Nuclear internal transcribed spacer (ITS) regions and chloroplast trnL intron and trnL/trnF spacer and matK sequences were used from 86 accessions to assess relationships among 31 European and South American species of Hypochaeris plus 18 representatives of related genera of tribe Cichorieae. The ITS tree shows high resolution compared to that of the maternally inherited trnL intron, trnL/F spacer, and matK sequences. The ITS and the combined tree reveal clades that agree well with sections of the genus established previously on morphological and cytological grounds, except for H. robertia, which groups with Leontodon helveticus and L. autumnalis. Monophyly of species of Hypochaeris from South America is strongly supported by both ITS and the joint matrix of ITS, trnL, and matK data. European species lie basal to South American taxa, which suggests that species in South America evolved from a single introduction from European progenitors and not from H. robertia as suggested previously. Low levels of sequence divergence among South American taxa suggest a pattern of rapid speciation, in contrast to much greater divergence among European representatives. Different species of Leontodon form two different clades that are also supported by chromosome numbers and morphology. Both nuclear and chloroplast markers suggest that Helminthotheca, Leontodon, and Picris are closely related to each other as well as to Hypochaeris.     

Molecular phylogenetics of Hippophae L. (Elaeagnaceae) based on the internal transcribed spacer (ITS) sequences of nrDNA

 The genus Hippophae comprises 7 species and 8 subspecies according to the latest classification, and has shown enormous ecological, nutrient and medicinal values. Here we analyzed the phylogenetic relationships among 15 taxa of the genus by comparing sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA). ITS sequences in Hippophae varied in length from 651 bp to 666 bp. The aligned sequences were 690 bp in length and 269 (39.0%) were variable sites with 150 being parsimony-informative. The amount of polymorphism observed within a taxon was extremely low in most taxa except for two putative hybrid species. The aligned sequences were analyzed by maximum parsimony (MP) and neighbor-joining (NJ) methods. In the strict consensus trees of parsimony analysis, the monophyly of Hippophae was supported by 100% bootstrap value. H. tibetana was at the basal position of the genus, and the remaining taxa formed two clades with high bootstrap support. The first clade included subspecies of H.␣rhamnoides and the other one consisted of remaining species. Parsimony analysis also suggested that the species H. tibetana, H. neurocarpa and H.␣salicifolia were all distinct. Although the sequence divergence among subspecies of H. rhamnoides was also remarkably high, the molecular data supported the monophyly of H. rhamnoides when H. rhamnoides subsp. gyantsensis Rousi was excxluded. The NJ trees showed essentially the same topology. The taxonomical arrangement that divided the genus into two sections was not supported based on the ITS sequences. However, the hybrid origin of H. goniocarpa and H. litangensis proposed previously was supported by the present ITS data. Received January 7, 2002; accepted May 10, 2002 Published online: November 22, 2002 Addresses of the authors: Kun Sun, Xuelin Chen, Ruijun Ma, Qin Wang, Institute of Botany, Northwest Normal University, Lanzhou 730070, China. Changbao Li, Song Ge (e-mail: gesong@ns.ibcas.ac.cn or song_ge@hotmail.com), Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.     

Phylogenetic and evolutionary insights into the Saxifraga pentadactylis complex (Saxifragaceae): variation in nrITS sequences

Variation in nrlTS sequences among seven members of a seemingly natural group of Saxifraga (the S. pentadactylis complex; series Pentadactyles ) is phylogenetically analyzed. The two most parsimonious trees indicate that the S. pentadactylis complex is not a monophyletic group, because 5. intricata is excluded and is most closely related to S. exarata (series Cespitosae ). A well-defined lineage includes, however, six of the seven members of the S. pentadactylis complex. The tree topology suggests that this remaining group of six taxa may have diverged in the northeastern part of the Iberian Peninsula. Two sublineages can be identified from the ITS phylogenetic reconstruction: S. losae-S.moncayensis and the three subspecies of S. pentadactylis (subspp. pentadactylis, willkommiana , and almanzorii ). The relationships between S. losae and S. moncayensis provide an example of north-south speciation along the Sistema Ibérico mountain range. The three subspecies of S. pentadactylis form a monophyletic group resolved into one clade containing subspp. willkommiana and almanzorii , sister to subsp. pentadactylis. The molecular evidence agrees with chorological, cytotaxonomical, chemosystematic, and reproductive data indicating two differentiation patterns within S. pentadactylis. Transition to predominant autogamy in subsp. almanzorii probably resulted in rapid reproductive isolation from the outcrossing subsp. willkommiana in part of the Sistema Central mountain range, as suggested by their two distinct floral types but similar ITS sequences. Allopatric separation of populations of subsp. willkommiana from subsp. pentadactylis (the Pyrenees) has resulted in molecular divergence and some morphological differentiation.     

Phylogenetic relationships of Empetraceae inferred from sequences of chloroplast gene matK and nuclear ribosomal DNA ITS region

We used sequences of nrDNA ITS and chloroplast gene matK to evaluate the monophyly of Empetrum and Corema and to examine phylogenetic relationships of the Empetraceae. Sequences of these two DNA markers were obtained for 11 plant samples, representing species of Empetrum from both the Southern and Northern Hemispheres, species and subspecies of Corema, and the monotypic Ceratiola. Sequences of four species of Rhododendron were used for rooting purposes. Our results show that species of Empetrum form a clade sister to the clade containing both Corema and Ceratiola. These two clades are strongly supported in both the matK and ITS trees, suggesting that Ceratiola is more closely related to Corema than to Empetrum, and is not of a hybrid origin between the ancestors of the latter two genera. In the matK tree, Corema conradii is more closely related to Ceratiola than to Corema album and C. album subsp. azoricum, whereas in the ITS tree, Ceratiola is allied with Corema album and C. album subsp. azoricum. This suggests that C. conradii might be a hybrid between ancestral populations of Ceratiola and C. album. The monophyly of Empetrum rejects the hypothesis of its independent origin in the two Hemispheres. Our trees also suggest the fact that the modern amphitropical distribution of Empetrum is the result of long distance dispersal, not of the vicarious events.     

Persistent nuclear ribosomal DNA sequence polymorphism in the Amelanchier agamic complex (Rosaceae)

Individual plants of several Amelanchier taxa contain many polymorphic nucleotide sites in the internal transcribed spacers (ITS) of nuclear ribosomal DNA (nrDNA). This polymorphism is unusual because it is not recent in origin and thus has resisted homogenization by concerted evolution. Amelanchier ITS sequence polymorphism is hypothesized to be the result of gene flow between two major North American clades resolved by phylogenetic analysis of ITS sequences. Western North American species plus A. humilis and A. sanguinea of eastern North America form one clade (A), and the remaining eastern North American Amelanchier make up clade B. Five eastern North American taxa are polymorphic at many of the nucleotide sites where clades A and B have diverged and are thought to be of hybrid origin, with A. humilis or A. sanguinea as one parent and various members of clade B as the other parent. Morphological evidence suggests that A. humilis is one of the parents of one of the polymorphic taxa, a microspecies that we refer to informally as A. "erecta." Sequences of 21 cloned copies of the ITS1- 5.8S gene-ITS2 region from one A. "erecta" individual are identical to A. humilis sequence or to the clade B consensus sequence, or they are apparent recombinants of A. humilis and clade B ITS repeats. Amelanchier "erecta" and another polymorphic taxon are suspected to be relatively old because both grow several hundred kilometers beyond the range of one of their parents. ITS sequence polymorphisms have apparently persisted in these two taxa perhaps because of polyploidy and/or agamospermy (asexual seed production), which are prevalent in the genus.      

Molecular phylogeny of Osmanthus(Oleaceae)based on non-coding chloroplast and nuclear ribosomal internal transcribed spacer regions

The phylogenetic relationships of Osmanthus Lour.were investigated using the nuclear ribosomal internal transcribed spacer(ITS)regions and non-coding chloroplast regions(psbA-trnH,trnL-F).The two datasets support the conclusion that Osmanthus is polyphyletic.with some species of the subtribe Oleinae nested within Osmanthus.Osmanthus didymopetalus P S.Green is nested within the clade formed by species of section Osmanthus in two trees.Osmanthus attenuatus P.S.Green.O.Funnanensis P.S.Green,and O gracilinervis R.L.Lu of traditional section Osmanthus are clearly divergent from other accessions,and do not form a monophyletic group with other Osmanthus accessions.Osmanthus marginatus Hemsl.is embedded in the clade formed by species of section Osmanthus in the ITS tree.In cpDNA trees all species of section Osmanthus are placed in the large clade and all species of section Leiolea formed a group.The taxonomic incongruence among trees for ITS and cpDNA indicate hybridization.as introgression may have occurred among some species of sections Osmanthus and Leiolea.Phylogeny of Osmanthus is discussed in light of molecular and morphological data,and a revised infrageneric classification with three sections(Leiolea,Siphosmanthu,and Osmanthus)is presented.The section Linocieroides is abandoned and united with section Osmanthus.     

Reticulate evolution patterns in western-Eurasian beeches

Reticulate evolution resulting from gene flow among diverged taxa was studied on the example of the Fagus sylvatica species complex in Europe and western Asia. F. sylvatica L. is one of the most widespread woody species of the Northern Hemisphere with two commonly recognized subspecies (namely, F. sylvatica subsp. sylvatica and F. sylvatica subsp. orientalis) and two putatively hybridogenous or intermediate taxa (F. moesiaca and F. taurica). Whereas the distribution of F. sylvatica subsp. sylvatica in Europe is almost continuous, the Asian range of F. sylvatica subsp. orientalis is fragmented into several larger regional populations. We studied genetic variation at 12 allozyme loci in 279 local subpopulations to assess whether previous contacts of regional populations left traces in their gene pools. Two approaches were used to infer potential reticulations: the reticulate network (Makarenkov and Legendre in J Comp Biol 11:195–212, 2004) and the neighbor-net network (Bryant and Moulton in Mol Biol Evol 21:255–265, 2004). A UPGMA dendrogram based on genetic distances between local populations revealed a high differentiation level within subsp. orientalis, whereby populations from Asia Minor, the Caucasus and the Alborz mts. were placed in different clusters. The reticulated network showed possible connections among adjacent populations, putatively resulting from previous contacts. The neighbor-net network also consisted of two major groups corresponding to F. sylvatica s. str. + F. moesiaca and F. orientalis including F. taurica. Regional populations of F. moesiaca are placed close to the basis of the European branch and are highly networked, indicating ambiguity in the phylogenetic signal. Similarly, three subgroups can be distinguished within the F. orientalis group and correspond well with broad regions of Asia Minor, the Caucasus and the Alborz. The Amanus regional population is intermediary between the subgroup of Asia Minor and the Caucasian subgroup. Crimean populations (i.e., putative hybrids) are placed near the basis of the subgraph. Two explanations of the observed reticulations are discussed: expansions and retreats of the range of beech associated with Pliocene and Pleistocene climatic fluctuations, resulting in contacts and exchanges of gene pools among regional populations, and sharing ancestral polymorphisms due to incomplete lineage sorting.     

Phylogenetic relationships and genetic diversity among members of theFestuca-Lolium complex (Poaceae) based on ITS sequence data

There have been few DNA sequencebased studies of phylogenetic relationships within theFestuca-Lolium complex. Here we infer the phylogeny of 31Festuca-Lolium taxa with a dataset of 116 ITS sequences. The results are consistent with previous studies that resolved two majorFestuca clades: one clade of fine fescues and another clade that containsLolium and associatedFestuca species. This study is unique in suggesting a third, basalFestuca clade, but support for the basal position of this group is low. Extensive sampling permitted investigation of the effects of lineage sorting and reticulate events on the evolution of the complex. Roughly half of the taxa show evidence of lineage sorting or reticulation, and the monophyly ofLolium has likely been obscured by reticulate events. Overall, polyploid species harbor higher levels of ITS sequence diversity than diploids; ITS sequence variants may provide clues to the identity of allopolyploid parents.     

Phylogenetics of the Thamnocalamus group and its allies (Gramineae: Bambusoideae): inference from the sequences of GBSSI gene and ITS spacer

Phylogenetics of 33 species (35 species in the ITS analysis) of the Thamnocalamus group and its allies inferred from partial sequences of the nuclear GBSSI gene and from those of the nuclear ribosomal ITS spacer was discussed in the present paper. The analyses of two separate data and combined data sets were performed using the parsimony method. Two species from Arundinaria and Acidosasa were used as outgroups. All three analyses supported the monophyly of the Thamnocalamus group and its allies, which have pachymorph rhizomes and semelauctant synflorescences with three stamens. The two sampled species of Chimonocalamus were resolved as a strongly supported monophyletic group and as basal in the Thamnocalamus group and its allies in the ITS and combined analyses. The resolution of the Thamnocalamus group and its allies in the GBSSI-gene-based tree was generally poor, while the gene still identified some clades with strongly internal supports, i.e., the Chimonocalamus clade, the Ampelocalamus clade, the clade of Thamnocalamus spathiflorus and its variety, that of Fargesia porphyrea and Yushania bojieana, and the clade of Fargesia edulis and Fargesia fungosa. The topology resulting from the GBSSI and ITS combined data analysis had a better resolution than those from the two separate data sets. T. spathiflorus and its variety comprised another strongly supported basal clade and may be next to the Chimonocalamus clade. The positions of the African Thamnocalamus tessellatus and Arundinaria (Yushania) alpina, and the monotypic Chinese endemic Gaoligongshania were problematic. The Thamnocalamus group per se was resolved as polyphyletic. Most species of Fargesia and Yushania formed a group with no bootstrap support. This assemblage was heterogeneous according to the morphological characters and further investigation is needed. This study implicated that the current limitation of three genera of Thamnocalamus, Fargesia (incl. Borinda) and Yushania may not reflect the true phylogenetic relationships of the complex. The phylogenetic utility of GBSSI gene in closely related woody bamboos was also evaluated.