Phylogenetic relationships and generic delimitation of Eurasian Aster (Asteraceae: Astereae) inferred from ITS, ETS and trnL-F sequence data

Background and Aims

The classification and phylogeny of Eurasian (EA) Aster (Asterinae, Astereae, Asteraceae) remain poorly resolved. Some taxonomists adopt a broad definition of EA Aster, whereas others favour a narrow generic concept. The present study aims to delimit EA Aster sensu stricto (s.s.), elucidate the phylogenetic relationships of EA Aster s.s. and segregate genera.

Methods

The internal and external transcribed spacers of nuclear ribosomal DNA and the plastid DNA trnL-F region were used to reconstruct the phylogeny of EA Aster through maximum parsimony and Bayesian analyses.

Key Results

The analyses strongly support an Aster clade including the genera Sheareria, Rhynchospermum, Kalimeris (excluding Kalimeris longipetiolata), Heteropappus, Miyamayomena, Turczaninowia, Rhinactinidia, eastern Asian Doellingeria, Asterothamnus and Arctogeron. Many well-recognized species of Chinese Aster s.s. lie outside of the Aster clade.

Conclusions

The results reveal that EA Aster s.s. is both paraphyletic and polyphyletic. Sheareria, Rhynchospermum, Kalimeris (excluding K. longipetiolata), Heteropappus, Miyamayomena, Turczaninowia, Rhinactinidia, eastern Asian Doellingeria, Asterothamnus and Arctogeron should be included in Aster, whereas many species of Chinese Aster s.s. should be excluded. The recircumscribed Aster should be divided into two subgenera and nine sections. Kalimeris longipetiolata, Aster batangensis, A. ser. Albescentes, A. series Hersileoides, a two-species group composed of A. senecioides and A. fuscescens, and a six-species group including A. asteroides, should be elevated to generic level. With the Aster clade, they belong to the Australasian lineages. The generic status of Callistephus should be maintained. Whether Galatella (including Crinitina) and Tripolium should remain as genera or be merged into a single genus remains to be determined. In addition, the taxonomic status of A. auriculatus and the A. pycnophyllus–A. panduratus clade remains unresolved, and the systematic position of some segregates of EA Aster requires further study.     

Phylogenetic relationships among Boleosoma darter species (Percidae: Etheostoma)

Darters represent a species rich group of North American freshwater fishes studied in the context of their diverse morphology, behavior, and geographic distribution. We report the first molecular phylogenetic analyses of the Boleosoma darter clade that includes complete species sampling. We estimated the relationship among the species of Boleosoma using DNA sequence data from a mitochondrial (cytochrome b) and a nuclear gene (S7 ribosomal protein intron 1). Our analyses discovered that the two Boleosoma species with large geographic distributions (E. nigrum and E. olmstedi) do not form reciprocally monophyletic groups in either gene trees. Etheostoma susanae and E. perlongum were phylogenetically nested in E. nigrum and E. olmstedi, respectively. While analysis of the nuclear gene resulted in a phylogeny where E. longimanum and E. podostemone were sister species, the mitochondrial gene tree did not support this relationship. Etheostoma vitreum was phylogenetically nested within Boleosoma in the mitochondrial DNA and nuclear gene trees. Our analyses suggest that current concepts of species diversity underestimate phylogenetic diversity in Boleosoma and that Boleosoma species likely provide another example of the growing number of discovered instances of mitochondrial genome transfer between darter species.     

A new species of Chiliotrichiopsis (Asteraceae: Astereae) from Peru

Chiliotrichiopsis peruviana Nesom, H. Rob. & Granda, a new species from Dept. Ayacucho in southwestern Peru, is described and illustrated. It is the only rayless species of the genus, now expanded to four species, and the only one that occurs outside of Argentina.Chiliotrichiopsis is one of six shrubby South American genera of Astereae (subtribe Hinterhuberinae) with paleate receptacles. Observations on morphology and a key to these genera provide perspective for the generic placement of the new species.     

Phylogenetic relationships among Lactuca (Asteraceae) species and related genera based on ITS-1 DNA sequences

Internal transcribed spacer (ITS-1) sequences from 97 accessions representing 23 species of Lactuca and related genera were determined and used to evaluate species relationships of Lactuca sensu lato (s.l.). The ITS-1 phylogenies, calculated using PAUP and PHYLIP, correspond better to the classification of Feráková than to other classifications evaluated, although the inclusion of sect. Lactuca subsect. Cyanicae is not supported. Therefore, exclusion of subsect. Cyanicae from Lactuca sensu Feráková is proposed. The amended genus contains the entire gene pool (sensu Harlan and De Wet) of cultivated lettuce (Lactuca sativa). The position of the species in the amended classification corresponds to their position in the lettuce gene pool. In the ITS-1 phylogenies, a clade with L. sativa, L. serriola, L. dregeana, L. altaica, and L. aculeata represents the primary gene pool. L. virosa and L. saligna, branching off closest to this clade, encompass the secondary gene pool. L. virosa is possibly of hybrid origin. The primary and secondary gene pool species are classified in sect. Lactuca subsect. Lactuca. The species L. quercina, L. viminea, L. sibirica, and L. tatarica, branching off next, represent the tertiary gene pool. They are classified in Lactuca sect. Lactucopsis, sect. Phaenixopus, and sect. Mulgedium, respectively. L. perennis and L. tenerrima, classified in sect. Lactuca subsect. Cyanicae, form clades with species from related genera and are not part of the lettuce gene pool.     

Phylogenetic relationships of the enigmatic species Serratula chinensis and Serratula forrestii (Asteraceae - Cardueae)

The phylogenetic relationships of the Chinese species Serratula forrestii and S. chinensis within the subtribe Centaureinae (Asteraceae – Cardueae) were investigated based on nuclear ribosomal DNA external and internal transcribed spacer sequences. Results indicated that Serratula s. l. is clearly polyphyletic, none of the two species showing close affinities to either Serratula s. str. or Klasea, a genus traditionally included in Serratula. Serratula forrestii has a basal position within the subtribe and has retained most plesiomorphic character states. Serratula chinensis is related to the genera of the Rhaponticum group. Its chromosome number was determined as 2n = 26, and the relationship between this species and the Rhapon-ticum group is discussed from a morphological and karyological point of view.     

Molecular evidence for the polyphyly of Olearia (Astereae: Asteraceae)

 Analyses of ITS sequences for 49 species of Olearia, including representatives from all currently recognised intergeneric sections, and 43 species from 23 other genera of Astereae, rooted on eight sequences from Anthemideae, provide no support for the monophyly of this large and morphologically diverse Australasian genus. Eighteen separate lineages of Olearia are recognised, including seven robust groups. Three of these groups and another eight species are placed within a primary clade incorporating representatives of Achnophora, Aster, Brachyscome, Calotis, Camptacra, Erigeron, Felicia, Grangea, Kippistia, Lagenifera, Minuria, Oritrophium, Peripleura, Podocoma, Remya, Solidago, Tetramolopium and Vittadinia. The remaining four groups and three individual species lie within a sister clade that also includes Celmisia, Chiliotrichum, Damnamenia, Pleurophyllum and Pachystegia. Relationships within each primary clade are poorly resolved. There is some congruence between this molecular estimate of the phylogeny and the distribution of types of abaxial leaf-hair, which is the basis of the present sectional classification of Olearia, but all states appear to have arisen more than once within the tribe. It is concluded that those species placed within the second primary clade should be removed from the genus, but the extent to which species placed within the first primary clade constitute a monophyletic group can only be resolved with further sequence data. Received November 12, 2001; accepted April 29, 2002 Published online: November 22, 2002 Addresses of authors: Edward W. Cross, Centre for Plant Biodiversity Research, CSIRO, GPO Box 1600, Canberra, ACT 2601, Australia (E-mail: ed.cross@csiro.au); Christopher J . Quinn, Royal Botanic Gardens, Mrs Macquaries Rd., Sydney, NSW 2000, Australia; Steven J. Wagstaff, Landcare Research, PO Box 69, Lincoln 8152, New Zealand.     

基于ITS序列探讨杜鹃花属马银花组的系统发育

以杜鹃花属叶状苞亚属Rhododendron　subg. Therorhodion (Maxim.) Gray 的叶状苞杜鹃R. redowskianum Maxim.为外类群,使用PAUP4.0b8软件对马银花亚属sub g. Azaleastrum Planch.的马银花组sect. Azaleastrum (Planch.) Maxim. 7种1 变种和长蕊杜鹃组sect. Choniastrum Planch. 2种及2个相关的单型亚属（异蕊杜鹃 亚属subg. Mumeazalea Max     

Phylogenetic relationships within Korthalsella (Viscaceae) based on nuclear ITS and plastid trnL-F sequence

The nuclear encoded internal transcribed spacer (ITS) region and the plastid encoded trnL-F region were sequenced for 25 populations of Korthalsella, a genus of reduced, monoecious, Old World misletoes. The molecular study confirms the hypothesis that branch shape and cladotaxy (the arrangement of branches with respect to their parent axis) are unreliable indicators of relationship in the genus and demonstrates that many of the taxa previously recognized are not monophyletic. Both gene regions identify three major subgroups within the genus and find lower level relationships within these subgroups highly correlated with geographic distance. An analysis based upon 18S and rbcL sequences identifies Ginalloa as the sister group to Korthalsella, which together with the branching order within the genus, indicates that Korthalsella originated in Papuasia and aids in elucidating evolution of the peculiar inflorescence structure. There are problems associated with species delimitation when evolutionary units are more restricted than morphological lineages, and justification is offered for recognizing only morphologically diagnosable monophyletic lineages as species. Varying substitution rates and differing modes of inheritance in ITS and trnL-F result in complementary utility of the two regions for elucidating infrageneric relationships in Korthalsella.     

Phylogenetic relationships among Artemisia species based on nuclear ITS and chloroplast psbA-trnH DNA markers

The taxonomic and phylogenetic relationships within the genus Artemisia s.l. (Asteraceae) are controversial, and it has been considered 1 to 8 different genera. This work re-investigated the phylogenetic relationships in Artemisia using nuclear ribosomal (ITS) and chloroplast psbA-trnH DNA sequences using three sections of Artemisia, Dracunculus, and Serphidium. Three phylogenetic trees were conducted separately on the basis of ITS, psbA-trnH and combined sequences using maximum parsimony. The results showed that the three sections were clearly separated from each other, and that the heterogamous Dracunculus and Artemisia are closely related to each other than either to homogamous Serphidium. This may suggest the taxonomic importance of capitulum morphology in Artemisia s.l. Our data also cast doubt on the use of cytogenetic similarity e.g., basic chromosome number in grouping Serphidium and Artemisia s.s. Furthermore, AMOVA analysis showed a higher level of ITS (55.29%) and combined ITS+cppsbA-trnH (55.63%) variations among sections. This provides further evidence for separation of these three sections and supports the phylogenetic results. The higher ITS nucleotide differences detected in Artemisia (30.4737) compared to very low value in Dracunculus (2.3333) and Serphidium (1.23077) may propose that the Artemisia comprises of several incipient sections. This supports the previous suggestion that Artemisia is a complex group.     

Phylogenetic relationships among Cucumis species based on the ribosomal internal transcribed spacer sequence and microsatellite markers

The phylogenetic relationships within the genus Cucumis (a total of 25 accessions belonging to 17 species) were studied using the nuclear ribosomal DNA internal transcribed spacer (ITS) region. The analysis included commercially important species such as melon (C. melo L.) and cucumber (C. sativus). Two additional cucurbit species, watermelon and zucchini, were also included as outgroups. The data obtained reflected the clustering of Cucumis species in four main groups, comprising accessions from cucumber, melon, C. metuliferus and the wild African species. Some of the species clustered in different positions from those reported in classifications previously described by other authors. The data obtained clearly identify a division between the 2n=2x = 14 species (C. sativus) and the 2n = 2x = 24 ones (C. melo and wild species). Within the wild species we identified a subgroup that included C. sagittatus and C. globosus. Oreosyce africana, also classified as Cucumis membranifolius, was shown to be nested within Cucumis. Three accessions previously classified as independent species were shown to be genotypes of Cucumis melo. A set of melon and cucumber SSRs were also used to analyse the Cucumis species and the results were compared with the ITS data. The differential amplification of the SSRs among the accessions made it possible to distinguish three main groups: melon, cucumber and the wild species, though with less detail than applying ITS. Some SSRs were shown to be specific for melon, but other SSRs were useful for producing PCR fragments in all species of the genus.We are grateful to NCRPIS, IPK in Gatersleben, Semillas Fitó S.A., Michel Pitrat and Fernando Nuez for providing seeds. We would also like to thank Vanessa Alfaro, Trinidad Martínez and Núria Galofré for their excellent technical assistance. This work was financed by project AGL2000-0360 of Spains Ministerio de Ciencia y Tecnología (MCYT). AJMs work was supported by a postdoctoral contract from Spains MCYT.     

基于ITS和matK序列的兰科沼兰族分子系统研究及二新种

沼兰族是兰科植物的大族之一,约2000种,除了极地和沙漠地区,全球均有分布.该族植物主要分布在热带地区,尤其在东南亚、热带美洲、非洲以及澳大利亚等地区种类非常丰富.目前,已有关于该族植物形态和分子系统的研究,但有关该族亚族和属间的系统关系尚不清楚,属的界定争议也较大.该文基于核基因片段 ITS 和叶绿体基因片段 mat K 序列,采用最大简约法、最大似然法贝叶斯推理分析法,对现有沼兰族主要属的123种植物和10个外类群植物进行了分子系统学研究.结果表明：沼兰族主要分为3个亚族分支,包括附生的鸢尾兰亚族(Oberoniinae)、地生的羊耳蒜亚族(Liparidinae)和沼兰亚族分支(Crepidium clade).鸢尾兰亚族包括6个属、羊耳蒜亚族分支包括5个属、沼兰亚族分支包括4个属;丫瓣兰亚族(Ypsilorchidinae)应归并为鸢尾兰亚族;Disticholiparis 属与 Stichorkis 属的模式标本相同,应并入 Stichorkis 属;沼兰属(Cre-pidium )和无耳沼兰属(Dienia )的唇瓣结构差异较大,但二者均为单系类群.此外,在收集野外实验材料过程中,发现了2种产自中国西南部和越南北部的沼兰族新种,分别命名为麻栗坡羊耳蒜(Platystyliparis mali-poensis G．D．Tang,X．Y．Zhuang & Z．J．Liu)和秉滔羊耳蒜(Cestichis pingtaoi G．D．Tang,X．Y．Zhuang &Z．J．Liu).     

Molecular authentication of Anthemis deserti Boiss. (Asteraceae) based on ITS2 region of nrDNA gene sequence

The dried plant material of medicinally important Anthemis deserti Boiss. (family: Asteraceae) especially when it remains in the powdered form often look similar to Anthemis melampodina Del.; and therefore, difficult to distinguish, finally lead to chances of adulteration. The adulteration in medicinal plants effects on the efficacy of the drugs. The molecular authentication of herbal plant materials such as based on the internal transcribed spacer 2 (ITS2) sequences of nuclear ribosomal DNA (nrDNA) is considered as more reliable method compared to other the biochemical or histological methods. The present study aims to molecular authentication ofA. deserti based on molecular phylogenetic analyses of ITS2 gene sequence of nrDNA region. The ITS2 region of nrDNA of A. deserti were sequenced, and the molecular phylogenetic analyses were performed together with the GenBank sequences. The Maximum Parsimony tree revealed the close relationships of A. deserti with A. melampodina; however, the Neighbor-Joining and Maximum Likelihood tree clearly revealed that A. deserti is distinct from A. melampodina, which is also supported by the differences in nucleotides at five diffident positions (i.e. 22, 28, 87, 175 and 198) in the DNA sequence alignment.     

Phylogenetic analysis of Silphium and subtribe Engelmanniinae (Asteraceae: Heliantheae) based on ITS and ETS sequence data

The phylogenetic relationships of Silphium and subtribe Engelmanniinae were examined using DNA sequence data. The internal transcribed spacer (ITS) region and the external transcribed spacer (ETS) region were sequenced for 39 specimens representing the six genera of subtribe Engelmanniinae (Berlandiera, Chrysogonum, Dugesia, Engelmannia, Lindheimera, and Silphium), plus five additional genera identified as closely related to the Engelmanniinae by chloroplast DNA restriction site analysis, and three outgroups. Phylogenetic analysis supported the monophyly of Silphium with Lindheimera as sister. Silphium can be divided into two sections based upon two well-supported clades that correspond to root type and growth form. These results also supported the expansion of subtribe Engelmanniinae to include Balsamorhiza, Borrichia, Rojasianthe, Vigethia, and Wyethia. We hypothesize that subtribe Engelmanniinae originated in Mesoamerica and later radiated to the United States. We suggest that the cypsela complex, which is present in Berlandiera, Chrysogonum, Engelmannia, and Lindheimera, arose only once and was subsequently lost in Silphium.     

ITS sequence data support a single origin for North American Astereae (Asteraceae) and reflect deep geographic divisions in Aster s.l

The Astereae is the largest tribe of Asteraceae in North America. Morphological diversity suggests that the North American assemblage is polyphyletic as 12 endemic genera, as well as lineages of the genus Erigeron and Conyza (Conyzinae), have been hypothesized to represent at least five separate invasions of North America from Africa, Australia, Eurasia, and South America. This hypothesis was tested with a phylogenetic analysis of nucleotide sequence data from the internal transcribed spacers (ITS) of nuclear ribosomal DNA. Sequences for 62 taxa represent seven outgroup taxa and all major Northern and Southern Hemisphere groups of Astereae, including broad taxonomic and geographic sampling of Conyzinae and Aster s.l. (sensu lato). Parsimony analyses indicate that all North American Astereae are members of a strongly supported clade, and that a diverse group of predominantly woody taxa from Africa, Australia, and South America, are basal Astereae. Furthermore, Aster s.l. is deeply polyphyletic as Eurasian taxa, including Aster s.s. (sensu stricto), appear more closely related to Southern Hemisphere taxa than to North American Aster segregates. There is only low to moderate agreement between proposed higher level Astereae relationships based on ITS and those based either on morphology or chloroplast restriction site data.     

基于ITS序列探讨珍珠菜属过路黄组的系统关系

测定了紫脉过路黄、临时救和过路黄的nrDNA ITS序列,并分析了珍珠菜属过路黄组17个物种的遗传距离及亲缘关系。结果表明,过路黄组植物的ITS序列长度在620～628间,一致性高达90.59%,种间遗传距离为0.002～0.199。系统发育树表明:(1)紫脉过路黄、临时救和小茄亲缘关系较近;(2)大叶过路黄、落地梅和过路黄亲缘关系较近;(3)山萝过路黄、贯叶过路黄、管茎过路黄、叶头过路黄、峨眉过路黄及三角叶过路黄亲缘关系较近。ITS序列分析结果为组内植物的鉴定、分类及系统进化提供了新的参考。     

Phylogenetic inferences in Antennaria (Asteraceae: Gnaphalieae: Cassiniinae) based on sequences from Nuclear Ribosomal DNA internal transcribed spacers (ITS)

The phylogenetic relationships among sexually reproducing species of Antennaria (Asteraceae) are poorly understood. An earlier cladistic analysis based on morphology did not fully resolve the phylogeny of these taxa and therefore a different approach using molecular data was explored. The internal transcribed spacer regions (ITS-1 and ITS-2) of nuclear ribosomal DNA were sequenced for 30 species of Antennaria and one species from each of the outgroup genera Anaphalis, Ewartia, Leontopodium, and Pseudognaphalium. The ITS-1 sequence in Antennaria ranged from 253 to 260 base pairs (bp) in length, and the proportion of nucleotide differences between pairs of species of Antennaria ranged from 1 to 14%. For ITS-2, the divergence between pairs of species of Antennaria ranged from 0 to 8%. ITS-2 is shorter than ITS-1, ranging from 213 to 219 bp. Phylogenetic analysis indicates that, relative to the outgroups included, Antennaria is a well-supported monophyletic group. Based on the genera surveyed, Leontopodium appears to be the sister genus of Antennaria. The general topology of the molecular trees agrees with that based on previous morphological analyses and indicates that Antennaria is composed of six clades of equal rank, corresponding to the traditionally recognized informal groups, the Geyeriae, Argenteae, Arcuatae, Dimorphae, Pulcherrimae, and Catipes. Sequence and morphological data indicate that the Alpinae and Dioicae are unnatural, polyphyletic units that should be abandoned and redefined as the monophyletic Catipes group. Phylogenetic analysis of ITS sequences also suggests the dissociation of A. stenophylla from the Dimorphae, where it is traditionally placed, and its affiliation with the Argenteae, as well as the placement of A. arcuata in its own group.