Molecular phylogenetic systematics and biogeography of tribe Neillieae (Rosaceae) using DNA sequences of cpDNA, rDNA, and LEAFY

A phylogeny of the tribe Neillieae (Rosaceae), which comprises Neillia, Stephanandra, and Physocarpus, was reconstructed based on nucleotide sequences of several regions of cpDNA, the ITS and ETS regions of rDNA, and the second intron of LEAFY, to elucidate relationships among genera and species in Neillieae and to assess the historical biogeography of the tribe. Phylogenetic analyses indicated that Physocarpus and Neillia-Stephanandra were strongly supported as monophyletic and suggested that Stephanandra may have originated by hybridization between two lineages of Neillia. Dispersal-vicariance analyses suggested that the most recent common ancestor of Neillieae may have occupied eastern Asia and western North America and that Physocarpus and Neillia-Stephanandra may have been split by an intercontinental vicariance event in the early Miocene. The biogeographic analyses also suggested that species of Neillia and Stephanandra diversified in eastern Asia, whereas in Physocarpus one dispersal event from western North America to eastern Asia occurred. Two divergent types of LEAFY sequences were found in the eastern North American species, P. opulifolius, but only one type was present in each plant. The two types of sequences may represent homeologous genes that originated by hybridization between P. capitatus and P. monogynus, both western North American species.     

Topological incongruence between nuclear and chloroplast DNA trees suggesting hybridization in the urophyllum group of the genus Fagopyrum (Polygonaceae)

We performed phylogenetic analyses of Fagopyrum species in the urophyllum group based on nucleotide sequences of two nuclear genes, FLORICAULA/LEAFY (FLO/LFY) and AGAMOUS (AG), and three segments of chloroplast DNA (cpDNA), rbcL-accD, trnK intron, and trnC-rpoB spacer. The FLO/LFY and AG sequences turned out to be phylogenetically more informative at the intrageneric level than the cpDNA sequences. Congruence among these gene trees, inferred by a maximum-likelihood (ML) method, demonstrated that topologies were partially incongruent between the nuclear and chloroplast DNA phylogenies. The nuclear DNA sequence data supported a monophyletic relation of F. statice, F. gilesii, and F. jinshaense, whereas the former two species formed another monophyletic relation with the F. capillatum-F. gracilipes-F. gracilipedoides-F. rubifolium clade excluding F. jinshaense in the synthetic cpDNA phylogeny. In addition, two divergent sequences of FLO/LFY were found in F. rubifolium (tetraploid). One of these was sister to F. gracilipedoides and another was sister to F. statice, and a monophyletic relation of these two genes was rejected by a bootstrap analysis. These results suggest that hybridization may have occurred during diversification of Fagopyrum species in the urophyllum group, and that F. rubifolium is possibly allotetraploid species.     

Molecular evidence for a Mediterranean origin of the Macaronesian endemic genus Argyranthemum (Asteraceae)

The internal transcribed spacers (ITS) of nuclear ribosomal DNA were sequenced for 52 species from 32 genera and eight subtribes of Anthemideae. Phylogenetic analyses of ITS data generated trees that are largely incongruent with the recent classification of Anthemideae; most of the subtribes examined are not resolved as monophyletic. However, ITS trees are congruent with morphological, isozyme, phytochemical, and chloroplast DNA (cpDNA) restriction site data in supporting a Mediterranean origin for Argyranthemum, the largest endemic genus of the Atlantic oceanic islands. A combined analysis of ITS sequences and cpDNA restriction sites indicates that Argyranthemum is sister to the other three genera of Chrysantheminae (i.e., Chrysanthemum, Heteranthemis, and Ismelia). Times of divergence of Argyranthemum inferred from the ITS sequences ranged between 0.26 and 2.1 million years ago (mya) and are lower than values previously reported from isozyme and cpDNA data (1.5-3.0 mya). It is likely that rate heterogeneity of the ITS sequences in the Anthemideae accounts for the low divergence-time estimates. Comparison of data for 20 species in Argyranthemum and Chrysantheminae indicates that the cpDNA restriction site approach provided much more phylogenetic information than ITS sequences. Thus, restriction site analyses of the entire chloroplast genome remain a valuable approach for studying recently derived island plants.     

Reticulate evolution in Thuja inferred from multiple gene sequences: implications for the study of biogeographical disjunction between eastern Asia and North America

The eastern Asia-North America disjunction is one of the most interesting biogeographical patterns, but its formation is still in much debate. Here nucleotide sequences of five cpDNA regions, nrDNA ITS and two low-copy nuclear genes (LEAFY, 4CL) were employed to reconstruct the phylogeny and to explore the historical biogeography of Thuja, a typical eastern Asia-North America disjunct genus. High topological discordance was observed between chloroplast and nuclear gene trees, even between different nuclear gene trees, suggesting that Thuja could have a reticulate evolutionary history due to multiple interspecific hybridization events. The eastern Asian species Thuja koraiensis might have obtained its chloroplast genome from the eastern North American species T. occidentalis by chloroplast capture, while the western North American species T. plicata is very likely to have inherited a recombinant cpDNA. Based on the phylogenetic analysis of multiple genes, DIVA-reconstruction of the distribution history, molecular clock estimation and fossil data, we inferred that Thuja could have originated from the high-latitude areas of North America in the Paleocene or earlier with subsequent expansion into eastern Asia through the Bering Land Bridge. The two eastern Asia species T. standishii and T. sutchuenensis have a sister relationship, and their split could have occurred in the Oligocene or early Miocene. In the present study, the selection of molecular markers in biogeographic studies was also discussed. Since most previous studies on the eastern Asia and North America disjunction are based on uniparentally inherited cpDNA and (or) directly sequenced nrDNA ITS data, the historical reticulate evolution in the studied groups might have been underestimated. Therefore, we suggest that multiple genes from different genomes, especially low-copy nuclear genes, be used in this research area in the future.     

Development of PCR primer sets for intron 1 of the low-copy gene LEAFY in Davalliaceae

? Premise of the study: Primers were designed for amplifying intron 1 of the single-copy nuclear LEAFY gene for species of Davalliaceae. ? Methods and Results: New primer sets were designed and successfully amplified for intron 1 of the LEAFY gene in 13 species representing the five genera of Davalliaceae. The orthology of these sequences was further confirmed by phylogenetic analyses. Site variation in LEAFY intron 1 sequences across genera of the Davalliaceae and among accessions of the Humata repens complex were 18% and 8%, respectively. Such variation was greater than that for the cpDNA atpB-rbcL intergenic spacer region across the same taxa and accessions. ? Conclusions: Using our newly designed primers, intron 1 of the LEAFY gene could be amplified for all species tested. In addition, this single-copy, biparentally inherited, and quickly evolving region showed considerable potential for addressing infraspecific-level questions.     

Phylogenetic Use of Noncoding Regions in the GenusGentianaL.: ChloroplasttrnL (UAA) Intron versus Nuclear Ribosomal Internal Transcribed Spacer Sequences

Sequence divergence was estimated within noncoding sequences of both chloroplast DNA (cpDNA)trnL (UAA) intron and nuclear ribosomal DNA (nrDNA) internal transcribed spacer sequences (ITS1 and ITS2) for 10 species of the genusGentianaL. (Gentianaceae). Comparisons of evolutionary rates among these sequences (cpDNA versus nrDNA, ITS1 versus ITS2) were performed. It appears that sequence divergence is on average two to three times higher in ITSs than in thetrnL intron sequences and higher in ITS1 than in ITS2. Both the cpDNA intron and ITSs of nrDNA give concordant phylogenetic trees. However, the ITS-based phylogeny displays higher bootstrap values. At the intrageneric level, at least inGentiana,ITSs (especially ITS2) sequences seem to be more appropriate in the assessment of plant phylogenies. Nevertheless, the cpDNAtrnL intron seems to be preferable at the intergeneric level.     

Phylogeny of Nolana (Solanaceae) of the Atacama and Peruvian deserts inferred from sequences of four plastid markers and the nuclear LEAFY second intron

The phylogeny of Nolana (Solanaceae), a genus primarily distributed in the coastal Atacama and Peruvian deserts with a few species in the Andes and one species endemic to the Galápagos Islands, was reconstructed using sequences of four plastid regions (ndhF, psbA-trnH, rps16-trnK and trnC-psbM) and the nuclear LEAFY second intron. The monophyly of Nolana was strongly supported by all molecular data. The LEAFY data suggested that the Chilean species, including Nolana sessiliflora, the N. acuminata group and at least some members of the Alona group, are basally diverged, supporting the Chilean origin of the genus. Three well-supported clades in the LEAFY tree were corroborated by the SINE (short interspersed elements) or SINE-like insertions. Taxa from Peru are grouped roughly into two clades. Nolana galapagensis from the Galápagos Island is most likely to have derived from a Peruvian ancestor. The monophyly of the morphologically well-diagnosed Nolana acuminata group (N. acuminata, N. baccata, N. paradoxa, N. parviflora, N. pterocarpa, N. rupicola and N. elegans) was supported by both plastid and LEAFY data. Incongruence between the plastid and the LEAFY data was detected concerning primarily the positions of N. sessiliflora, N. galapagensis, taxa of the Alona group and the two Peruvian clades. Such incongruence may be due to reticulate evolution or in some cases lineage sorting of plastid DNA. Incongruence between our previous GBSSI trees and the plastid-LEAFY trees was also detected concerning two well-supported major clades in the GBSSI tree. Duplication of the GBSSI gene may have contributed to this incongruence.     

Phylogeographically concordant chloroplast DNA divergence in sympatric Nothofagus s.s. How deep can it be?

? Here, we performed phylogenetic analyses and estimated the divergence times on mostly sympatric populations of five species within subgenus Nothofagus. We aimed to investigate whether phylogenetic relationships by nuclear internal transcribed spacer (ITS) and phylogeographic patterns by chloroplast DNA (cpDNA) mirror an ancient evolutionary history that was not erased by glacial eras. Extant species are restricted to Patagonia and share a pollen type that was formerly widespread in all southern land masses. Weak reproductive barriers exist among them. ? Fifteen cpDNA haplotypes resulted from the analysis of three noncoding regions on 330 individuals with a total alignment of 1794 bp. Nuclear ITS data consisted of 822 bp. We found a deep cpDNA divergence dated 32 Ma at mid-latitudes of Patagonia that predates the phylogenetic divergence of extant taxa. Other more recent breaks by cpDNA occurred towards the north. ? Complex paleogeographic features explain the genetic discontinuities. Long-lasting paleobasins and marine ingressions have impeded transoceanic dispersal during range expansion towards lower latitudes under cooler trends since the Oligocene. ? Cycles of hybridization-introgression among extant and extinct taxa have resulted in widespread chloroplast capture events. Our data suggest that Nothofagus biogeography will be resolved only if thorough phylogeographic analyses and molecular dating methods are applied using distinct genetic markers.     

Molecular evidence for bicontinental hybridogenous genomic constitution in Lepidium sensu stricto (Brassicaceae) species from Australia and New Zealand

Lepidium sensu stricto (s.s.) (Brassicaceae) (ca. 150 species) is distributed worldwide with endemic species on every continent. It is represented in Australia and New Zealand by 19 and seven native species, respectively. In the present study we used a nuclear ribosomal internal transcribed spacer (ITS) phylogeny in comparison with a cpDNA phylogeny to unravel the origin of Australian/New Zealand species. Although phylogenetic relationships within Lepidium s.s. were not fully resolved, the cpDNA data were in agreement with a Californian origin of Lepidium species from Australia/New Zealand. Strongly conflicting signals between the cp- and nuclear DNA phylogenetic analysis clearly indicated hybridogenous genomic constitution of Australian Lepidium s.s. species: All 18 studied Australian/New Zealand Lepidium s.s. species examined shared a Californian cpDNA type. While eleven Australian/New Zealand species appeared to harbor a Californian ITS type, a group of seven species shared a South African ITS type. This pattern is most likely explained by two trans-oceanic dispersals of Lepidium from California and Africa to Australia/New Zealand and subsequent hybridization followed by homogenization of the ribosomal DNA either to the Californian or South African ITS type in the two different lineages. Calibration of our molecular trees indicates a Pliocene/Pleistocene origin of Lepidium in Australia/New Zealand. Low levels of cpDNA and ITS sequence divergence and unresolved topologies within Australian/New Zealand species suggest a rapid and recent radiation of Lepidium after the hybridization event. This coincides with dramatic climatic changes in that geological epoch shaping the composition of the vegetation.     

Phylogenetic reticulation in subtribe Helianthinae

Incongruence between phylogenetic estimates based on nuclear and chloroplast DNA (cpDNA) markers was used to infer that there have been at least two instances of chloroplast transfer, presumably through wide hybridization, in subtribe Helianthinae. One instance involved Simsia dombeyana, which exhibited a cpDNA restriction site phenotype that was markedly divergent from all of the other species of the genus that were surveyed but that matched the restriction site pattern previously reported for South American species of Viguiera. In contrast, analysis of sequence data from the nuclear ribosomal DNA internal transcribed spacer (ITS) region showed Simsia to be entirely monophyletic and placed samples of S. dombeyana as the sister group to the relatively derived S. foetida, a result concordant with morphological information. A sample of a South American species of Viguiera was placed by ITS sequence data as the sister group to a member of V. subg. Amphilepis, which was consistent with cpDNA restriction site data. Samples of Tithonia formed a single monophyletic clade based on ITS sequence data, whereas they were split between two divergent clades based on cpDNA restriction site analysis. The results suggested that cpDNA transfer has occurred between taxa diverged to the level of morphologically distinct genera, and highlight the need for careful and complete assessment of molecular data as a source of phylogenetic information.     

The internal transcribed spacer of nuclear ribosomal DNA in the gymnosperm Gnetum

We analyze the structure of the internal transcribed spacers ITS1 and ITS2 of the nuclear ribosomal DNA in the gymnosperm Gnetum, using a phylogenetic framework derived mainly from an intron in the nuclear low-copy LEAFY gene. Gnetum comprises 25-35 species in South America, Africa, and Asia, of which we sampled 16, each with two to six clones. Criteria used to assess ITS functionality were highly divergent nucleotide substitution, GC content, secondary structure, and incongruent phylogenetic placement of presumed paralogs. The length of ITS1 ranged from 225 to 986 bp and that of ITS2 from 259 to 305 bp, the largest ranges so far reported from seed plants. Gnetum ITS1 contains two informative sequence motifs, but different from other gymnosperms, there are only few and short (7-13 bp) tandem repeats. Gnetum ITS2 contains two structural motifs, modified in different clades by shortening of stems and loops. Conspecific sequences grouped together except for two recombinant pseudogenes that had ITS1 of one clade and ITS2 of another. Most of the pseudogenic ITS copies, paralogs, and putative chimeras occurred in a clade that according to a fossil-calibrated chloroplast-DNA clock has an age of a few million years. Based on morphology and chromosome numbers, the most plausible causes of the observed high levels of ITS polymorphism are hybridization, allopolyploidy, and introgression.     

Potential phylogenetic utility of the low-copy nuclear gene pistillata in dicotyledonous plants: comparison to nrDNA ITS and trnL intron in Sphaerocardamum and other Brassicaceae.

We report the potential phylogenetic utility of DNA sequence data from the last 700 bp of a ca. 1-kb intron of the MADS-box gene pistillata from a sampling of Sphaerocardamum species and other Brassicaceae. These results are compared with nrDNA ITS and the chloroplast trnL intron for the same taxa to demonstrate the potential phylogenetic utility of this pistillata intron and to identify potential historically independent sequences for an ongoing study of relationships within Sphaerocardamum. Analyses of the DNA sequence data for Brassicaceae indicated that pairwise divergences and potentially informative characters were higher in the pistillata intron (0.6-30.8%, 284 characters) and ITS (0-24%, 94 characters) than in the chloroplast trnL intron (0-4.2%, 17 characters). A comparison of Sphaerocardamum sequences identified low divergences and numbers of informative characters for trnL intron (0-2.4%, 1 character) and nrDNA ITS (0-2.5%, 2 characters) and substantially more variation among the pistillata sequences (0.15-3.7%, 19 characters). Phylogenetic analyses of these pistillata sequences fully resolve ingroup relationships without character conflict. Results of pistillata PCR amplifications from a broader dicot sample showed that some primers may be useful in amplifying orthologous pistillata sequences. Ultimately this pistillata intron may be a valuable source of phylogenetic characters at lower taxonomic levels.     

Speciation process of <Emphasis Type="Italic">Salvia isensis</Emphasis> (Lamiaceae), a species endemic to serpentine areas in the Ise-Tokai district,Japan, from the viewpoint of the contradictory phylogenetic trees generated from chloroplast and nuclear DNA

To understand the speciation process of Salvia isensis (Lamiaceae), a species endemic to a special environment (serpentine areas in the Ise-Tokai district, central Honshu, Japan), chloroplast DNA (cpDNA) and nuclear ribosomal DNA (nrDNA) were employed to analyze the phylogenetic relationships of S. isensis with related species in Japan. Allozymic polymorphisms were also used to analyze genetic relationships among Salvia species. A contradiction in the phylogenetic positions of species studied was detected when phylogenetic trees were constructed using cpDNA or nrDNA, i.e., S. isensis was a sister to the other species in phylogenetic trees generated from cpDNA, while S. japonica was a sister to the other species in the case of nrDNA. Genetic relationships between Salvia species estimated from allozymic polymorphisms did not contradict to the topology for nrDNA. Using the present results, the speciation process of S. isensis is discussed with regard to introgressive gene exchanges between related species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Phylogeny, biogeography, and processes of molecular differentiation in Quercus subgenus Quercus (Fagaceae).

Quercus is one of the most abundant and economically important genera of woody plants in the Northern Hemisphere. To infer phylogenetic relationships within Quercus subgenus Quercus, chloroplast DNA (cpDNA) restriction sites and nucleotide sequences of the internal transcribed spacers (ITS) and the 5.8S coding region of the nuclear ribosomal DNA repeat were obtained for 44 individuals, including 25 species, intraspecific samples, and three outgroups. Separate parsimony analyses of each data set showed that individual gene trees were congruent and often complementary in supporting clades that generally corresponded to previously recognized taxonomic groups. Only one instance of strongly supported gene tree incongruence was detected and this anomalous pattern was explained best by ancient introgression of cpDNA across sectional boundaries. Simultaneous parsimony analysis of the pruned data sets supported the recognition of the strictly Eurasian section Cerris and resolved a novel hypothesis for the major infrageneric groups (Cerris- (Lobatae- (Protobalanus + Quercus sensu stricto))). The biogeographic hypothesis that all major oak lineages evolved locally at middle latitudes within the general distribution of their fossil ancestors was fully supported. This set of relationships also suggested a New World origin for the widespread white oaks of the Northern Hemisphere (section Quercus s. s.). For both data sets, inter- and intraspecific sampling within section Protobalanus showed little correspondence to morphological species. Greater cladistic structure among the samples was obtained by cpDNA restriction sites and two well-delimited plastomes types comprising a total of 15 distinct haplotypes were resolved. Haplotypes of 2 of the peripheral species in this species complex occupy terminal portions of one of the plastome clades, suggesting a more recent origin relative to those of more widespread species. The phylogeography of the two divergent plastome types suggested a north-south pattern, consistent with a Late Tertiary disjunction in the ancestral distribution of section Protobalanus.     

Reticulate phylogenetics and phytogeographical structure of Heliosperma (Sileneae, Caryophyllaceae) inferred from chloroplast and nuclear DNA sequences

The Balkan Peninsula is known to be one of the most diverse and species-rich parts of Europe, but its biota has gained much less attention in phylogenetic and evolutionary studies compared to other southern European mountain systems. We used nuclear ribosomal internal transcribed spacer (ITS) sequences and intron sequences of the chloroplast gene rps16 to examine phylogenetic and biogeographical patterns within the genus Heliosperma (Sileneae, Caryophyllaceae). The ITS and rps16 intron sequences both support monophyly of Heliosperma, but the data are not conclusive with regard to its exact origin. Three strongly supported clades are found in both data sets, corresponding to Heliosperma alpestre, Heliosperma macranthum and the Heliosperma pusillum clade, including all other taxa. The interrelationships among these three differ between the nuclear and the plastid data sets. Hierarchical relationships within the H. pusillum clade are poorly resolved by the ITS data, but the rps16 intron sequences form two well-supported clades which are geographically, rather than taxonomically, correlated. A similar geographical structure is found in the ITS data, when analyzed with the NeighbourNet method. The apparent rate of change within Heliosperma is slightly higher for rps16 as compared to ITS. In contrast, in the Sileneae outgroup, ITS substitution rates are more than twice as high as those for rps16, a situation more in agreement with what has been found in other rate comparisons of noncoding cpDNA and ITS. Unlike most other Sileneae ITS sequences, the H. pusillum group sequences display extensive polymorphism. A possible explanation to these patterns is extensive hybridization and gene flow within Heliosperma, which together with concerted evolution may have eradicated the ancient divergence suggested by the rps16 data. The morphological differentiation into high elevation, mainly widely distributed taxa, and low elevation narrow endemics is not correlated with the molecular data, and is possibly a result of ecological differentiation.     

基于ITS序列分析豹子花属与5种百合的亲缘关系

以滇蜀豹子花和多斑豹子花为材料,采用PCR直接测序法测定其ITS序列,结合GenBank中其它3种豹子花和5种百合的ITS序列,构建了这10种植物的系统发育树.结果表明:(1)10种植物的ITS序列长度在625bp～627 bp之间,总G C含量在60.38%～61.12%之间,5.8S的G C含量除大理百合为45.4%外,其余9种植物为55.01%或54.60%,说明ITS序列在进化上保守性较强,同属不同种甚至不同属间的长度差异不明显;(2)NJ、MP、ME聚类树的分支趋势一致,都是豹子花属植物先聚在一起再和5种百合相聚,滇西豹子花和豹子花在3种聚类树中都以99%以上的支持率聚成一支,说明这2个种的亲缘关系最近;(3)在10种植物中,形态相似且分布海拔和区域重叠的种类先相聚,说明这些物种的亲缘关系密切.     

Phylogenetic systematics and character evolution in the angiosperm family Haloragaceae

The poorly known Haloragaceae R. Br. (Saxifragales) are highly diverse in habit (small trees to submerged aquatics) and labile in floral merosity (2-4), both uncommon among the core eudicots. This family has a cosmopolitan distribution, but taxonomic diversity is concentrated in Australia. An explicit phylogenetic approach has not previously been utilized to examine relationships or character evolution in this family. We used molecular evidence from nrDNA ITS and cpDNA trnK and matK regions under both Bayesian and parsimony analyses to address phylogenetic relationships. Combined molecular analyses defined a monophyletic Haloragaceae with the woody genera (Haloragodendron, Glischrocaryon) sister to the rest. Relationships among many genera were well resolved, with genera as currently delimited generally well supported, although there were notable exceptions; a new genus (Trihaloragis) is recognized, and the aquatic genus Meionectes is again distinct from Haloragis. Three new species combinations are also recognized. There are multiple (two or three) origins of the submerged aquatic habit in the family and potentially an intermediate reversal to the terrestrial habit, neither previously demonstrated in a core eudicot family using an explicit phylogenetic hypothesis. Ancestral character analyses suggest two origins of trimerous flowers and multiple reductions to dimerous flowers throughout Haloragaceae.     

Divergent and reticulate species relationships in Leucaena (Fabaceae) inferred from multiple data sources: insights into polyploid origins and nrDNA polymorphism

Previous analyses of species relationships and polyploid origins in the mimosoid legume genus Leucaena have used chloroplast DNA (cpDNA) restriction site data and morphology. Here we present an analysis of a new DNA sequence data set for the nuclear ribosomal DNA (nrDNA) 5.8S subunit and flanking ITS 1 and ITS 2 spacers, a simultaneous analysis of the morphology, ITS and cpDNA data sets for the diploid species, and a detailed comparison of the cpDNA and ITS gene trees, which include multiple accessions of all five tetraploid species. Significant new insights into species relationships and polyploid origins, including that of the economically important tropical forage tree L. leucocephala, are discussed. Heterogeneous ITS copy types, including 26 putative pseudogene sequences, were found within individuals of four of the five tetraploid and one diploid species. Potential pseudogenes were identified using two pairwise comparison approaches as well as a tree-based method that compares observed and expected proportions of total ITS variation contributed by the 5.8S subunit optimized onto branches of one of the ITS gene trees. Inclusion of putative pseudogene sequences in the analysis provided evidence that some pseudogenes in allopolyploid L. leucocephala are not the result of post-allopolyploidization gene silencing, but were inherited from its putative diploid maternal progenitor L. pulverulenta.     

Chloroplastrps16 intron phylogeny of the tribeSileneae (Caryophyllaceae)

Intron sequences of the chloroplast generps16 from 46 species were used to examine phylogenetic relationships indicated by nrDNA ITS sequence variation in the tribeSileneae (Caryophyllaceae, Caryophylloideae). This region has previously not been utilized for phylogenetic purposes but the results presented here suggest that it is a consistent and valuable complement to the ITS sequences. Therps16 intron trees are largely congruent with the ITS trees. All the major hypotheses suggested by the ITS data are supported, often at similar bootstrap levels. The joint usage ofrps16 intron and ITS sequences provides a powerful tool for resolving many of the difficult taxonomic issues in the tribeSileneae. Dedicated to emer. Univ.-Prof. DrFriedrich Ehrendorfer on the occasion of his 70th birthday