Characterization, comparison, and phylogenetic analyses of chloroplast genomes of Euphorbia species.

The genus Euphorbia (Euphorbiaceae) has near-cosmopolitan distribution and serves as a significant resource for both ornamental and medicinal purposes. Despite its economic importance, Euphorbia's taxonomy has long been challenged by the intricate nature of morphological traits exhibiting high levels of convergence. While molecular markers are essential for phylogenetic studies, their availability for Euphorbia has been limited. To address this gap, we conducted comparative analyses focusing on the chloroplast (CP) genomes of nine Euphorbia species, incorporating three newly sequenced and annotated accessions. In addition, phylogenetic informativeness and nucleotide diversity were computed to identify candidate markers for phylogenetic analyses among closely related taxa in the genus. Our investigation revealed relatively conserved sizes and structures of CP genomes across the studied species, with notable interspecific variations observed primarily in non-coding regions and IR/SC borders. By leveraging phylogenetic informativeness and nucleotide diversity, we identified rpoB gene as the optimal candidate for species delimitation and shallow-level phylogenetic inference within the genus. Through this comprehensive analysis of CP genomes across multiple taxa, our study sheds light on the evolutionary dynamics and taxonomic intricacies of Euphorbia, offering valuable insights into its CP genome evolution and taxonomy.

Comparative plastomes of eight subgenus Chamaesyce plants and system authentication of Euphorbiae Humifusae Herba.

Euphorbiae Humifusae Herba (EHH) was provided with medicinal and edible uses, but frequently was adulterated with its closely related species. Hence, this study sought to identify EHH via an integrated approach comprising data from its morphological evaluation, HPLC analysis, comparative plastomes analysis and allele-specific PCR identification. First, the morphological characteristics of 8 subgenus Chamaesyce plants were summarized. Then, HPLC analysis showed that 18 batches of EHH were adulterated or unqualified. Furthermore, the plastomes of the 8 subg. Chamaesyce species were analyzed. Phylogenetic analysis revealed a sister relationship among the 8 subg. Chamaesyce species. The allele-specific PCR authentication was developed by the nucleotide polymorphisms (SNPs) and insertions or deletions (InDels) analysis. The results of allele-specific PCR showed that 27 batches of EHH were adulterated, indicating that the superior sensitivity of molecular authentication over the other methods used. This study provided a reference for rational use and phylogenetic research of EHH.

The sweet tabaiba or there and back again: phylogeographical history of the Macaronesian Euphorbia balsamifera.

BACKGROUND AND AIMS: Biogeographical relationships between the Canary Islands and north-west Africa are often explained by oceanic dispersal and geographical proximity. Sister-group relationships between Canarian and eastern African/Arabian taxa, the 'Rand Flora' pattern, are rare among plants and have been attributed to the extinction of north-western African populations. Euphorbia balsamifera is the only representative species of this pattern that is distributed in the Canary Islands and north-west Africa; it is also one of few species present in all seven islands. Previous studies placed African populations of E. balsamifera as sister to the Canarian populations, but this relationship was based on herbarium samples with highly degraded DNA. Here, we test the extinction hypothesis by sampling new continental populations; we also expand the Canarian sampling to examine the dynamics of island colonization and diversification. METHODS: Using target enrichment with genome skimming, we reconstructed phylogenetic relationships within E. balsamifera and between this species and its disjunct relatives. A single nucleotide polymorphism dataset obtained from the target sequences was used to infer population genetic diversity patterns. We used convolutional neural networks to discriminate among alternative Canary Islands colonization scenarios. KEY RESULTS: The results confirmed the Rand Flora sister-group relationship between western E. balsamifera and Euphorbia adenensis in the Eritreo-Arabian region and recovered an eastern-western geographical structure among E. balsamifera Canarian populations. Convolutional neural networks supported a scenario of east-to-west island colonization, followed by population extinctions in Lanzarote and Fuerteventura and recolonization from Tenerife and Gran Canaria; a signal of admixture between the eastern island and north-west African populations was recovered. CONCLUSIONS: Our findings support the Surfing Syngameon Hypothesis for the colonization of the Canary Islands by E. balsamifera, but also a recent back-colonization to the continent. Populations of E. balsamifera from northwest Africa are not the remnants of an ancestral continental stock, but originated from migration events from Lanzarote and Fuerteventura. This is further evidence that oceanic archipelagos are not a sink for biodiversity, but may be a source of new genetic variability.

Antifungal activity of Euphorbia species against moulds responsible of cereal ear rots.

AIMS: This work aimed to identify secondary metabolites from aerial parts of Euphorbia species functional for control of toxigenic Fusarium species responsible of cereal grain rots. METHODS AND RESULTS: Aerial parts of Euphorbia serpens, Euphorbia schickendantzii and Euphorbia collina were sequentially extracted with hexane, ethyl acetate and methanol. The extracts were tested against strains of Fusarium verticillioides and Fusarium graminearum by microdilution tests. The hexane extract of E. collina provided the lowest IC50 s on both fungal species. Further fractionation showed that cycloartenol (CA) and 24-methylenecycloartanol are associated to the moderate inhibitory effect of the hexane extract on fungal growth.Sublethal concentrations of CA and 24MCA blocked deoxynivalenol (DON) and fumonisins production.CA and 24MCA co-applied with potassium sorbate, a food preservative used for Fusarium control, synergized the growth inhibition of fungi. The mixtures reduced mycotoxins accumulation when applied at sublethal concentrations. CONCLUSIONS: CA and 24MCA inhibited both fungal growth and mycotoxins production. This fact is an advantage respect to potassium sorbate which increased the mycotoxins accumulation at sublethal concentrations. SIGNIFICANCE AND IMPACT OF THE STUDY: CA and 24MCA synergized potassium sorbate and their mixtures offer a lower mycotoxigenic risk than potassium sorbate for control of the Fusarium species.

Macrocyclic diterpenoids from the seeds of Euphorbia peplus with potential activity in inducing lysosomal biogenesis.

The first phytochemical investigation of the seeds of Euphorbia peplus led to the isolation and characterization of five new (1-5), named euphopepluanones A-E, and five known diterpenoids (6-10). Their structures were established by extensive spectroscopic analysis and X-ray crystallographic experiments. Euphopepluanones A-E (1-3) feature a very rare 5/11/5-tricyclic skeleton, and euphopepluanones D-E (4-5) represent the first report of lathyrane type diterpenoids found in E. peplus. The new compounds 1-5 were assessed for their activities to induce lysosomal biogenesis through LysoTracker Red staining, in which compounds 1 and 3 could significantly induce lysosomal biogenesis. In addition, compounds 1 and 3 could promote the nuclear translocation of TFEB, a master transcriptional factor of lysosomal genes, indicating that compounds 1 and 3 induced lysosomal biogenesis through activation of TFEB.

Cytotoxicity and Chromatographic Fingerprinting of Euphorbia Species Used in Traditional Medicine.

BACKGROUND AND OBJECTIVE: Chromatographic fingerprinting of plant species play an important role in species identification and standardization of plant based health products. Some of the Euphorbia species are used in folk medicine, yet majority of these exhibit various degrees of toxicity. It becomes a challenge to distinguish the toxic from the non-toxic species. The study aimed to evaluate cytotoxicity and to determine the method for fingerprinting the chemical constituents of the selected Euphorbia species to identify markers of toxicity. MATERIALS AND METHODS: Hexane, DCM, ethyl acetate and methanol extracts of E. arabica, E. bupleurifolia, E. enopla, E. gorgonis, E. horrida indigenous and E. horrida var. were examined in mammalian vero cell line using MTT cell viability test assay. The presence of secondary metabolites and proteins were assessed in the plant extracts and thin layer chromatography was used to identify toxicity markers. RESULTS: The hexane and DCM extracts of E. arabica, E. bupleurifolia and the DCM extract of E. horrida var. exhibited the highest cell growth inhibition reaching IC50 at a concentration of 10 µg mL-1. Both polar and non-polar extracts of E. enopla exhibited cell growth inhibition with the hexane extract reaching IC50 at a concentration of 10 µg mL-1. Euphorbia gorgonis and E. horrida indigenous were not active against the vero cell line. Secondary metabolites were detected, however, proteins were not detected in all six Euphorbia species. The TLC profiles of toxic extracts revealed additional bands which were absent in non-toxic species. CONCLUSION: It is concluded that the TLC method developed in this study can be used as a quick screen method to possibly distinguish toxic from non-toxic species, as well as in identifying the studied species.

Applications of Chromatographic Techniques for Fingerprinting of Toxic and Non-toxic Euphorbia Species.

BACKGROUND AND OBJECTIVE: Euphorbia species have historically been used as medicinal plants to treat different ailments. However, some species have been reported to exhibit various degrees of toxicity. It becomes critical to distinguish toxic species from those that are non-toxic, for a particular application. The aim of the study was to determine the method for fingerprinting the chemical constituents of the selected toxic and non-toxic Euphorbia species to identify markers of toxicity. MATERIAL AND METHODS: Hexane, DCM, methanol, ethyl acetate and water plant extracts of Euphorbia ammak, clavarioides, caerulescens, polygona and trigona were investigated for their cytotoxic activities towards the mammalian Vero cell line using MTT cell viability test assay. The presence of secondary metabolites and proteins were assessed in the plant extracts. Moreover, the study used chromatographic methods to fingerprint the plant extracts to identify toxicity markers. RESULTS: The DCM extract of E. ammak exhibited the highest cell growth inhibition at all concentrations tested. The non-polar extracts of E. clavarioides exhibited the highest cell growth inhibition activity with hexane extract reaching IC50 at 1 µg mL-1. The DCM extract of E. caerulescens reached IC50 at a concentration of 10 µg mL-1, while other extracts didn't show any activity. The hexane and DCM extracts of E. polygona exhibited the highest cell growth inhibition activity, reaching IC50 at a concentration of 10 µg mL-1. All 4 extracts of E. trigona didn't show cell growth inhibition. All Euphorbia species showed the presence of secondary metabolites. The biuret and xanthoprotein methods indicated that there were no proteins detected in all 5 Euphorbia species. TLC profiles of toxic extracts revealed additional bands which were absent in non-toxic species. CONCLUSION: It is concluded that the TLC method developed in this study can be used as a quick screen method to possibly distinguish toxic from non-toxic species, as well as in identifying the studied species.

The Chromosome-Based Rubber Tree Genome Provides New Insights into Spurge Genome Evolution and Rubber Biosynthesis.

The rubber tree, Hevea brasiliensis, produces natural rubber that serves as an essential industrial raw material. Here, we present a high-quality reference genome for a rubber tree cultivar GT1 using single-molecule real-time sequencing (SMRT) and Hi-C technologies to anchor the ∼1.47-Gb genome assembly into 18 pseudochromosomes. The chromosome-based genome analysis enabled us to establish a model of spurge chromosome evolution, since the common paleopolyploid event occurred before the split of Hevea and Manihot. We show recent and rapid bursts of the three Hevea-specific LTR-retrotransposon families during the last 10 million years, leading to the massive expansion by ∼65.88% (∼970 Mbp) of the whole rubber tree genome since the divergence from Manihot. We identify large-scale expansion of genes associated with whole rubber biosynthesis processes, such as basal metabolic processes, ethylene biosynthesis, and the activation of polysaccharide and glycoprotein lectin, which are important properties for latex production. A map of genomic variation between the cultivated and wild rubber trees was obtained, which contains ∼15.7 million high-quality single-nucleotide polymorphisms. We identified hundreds of candidate domestication genes with drastically lowered genomic diversity in the cultivated but not wild rubber trees despite a relatively short domestication history of rubber tree, some of which are involved in rubber biosynthesis. This genome assembly represents key resources for future rubber tree research and breeding, providing novel targets for improving plant biotic and abiotic tolerance and rubber production.

Tumor Cell Death via Apoptosis and Improvement of Activated Lymphocyte Cytokine Secretion by Extracts from Euphorbia Hebecarpa and Euphorbia Petiolata.

Background: Immunomodulatory materials from natural herbs and the characterization of their immune enhancement effects may have tremendous potential as cancer treatment. The aim of the present study was to investigate the apoptosis-inducing activities of Euphorbia hebecarpa Boiss and Euphorbia petiolata Banks & Sol. plant extracts and their effects on cytokine secretion by lymphocytes. Materials and Methods: We assessed the apoptosis-inducing effect of the plants' hexane extracts on previously determined sensitive cell lines (HeLa for E. hebecarpa and K562 for E. petiolata) by flow cytometry and measurement of caspase 3 activation. The apoptosis-related gene expressions were examined by real-time PCR. The effects of the extracts on lymphocyte proliferation and cytokine secretion were examined. Results: Flow cytometry analysis showed that the inhibitory effect of the extracts on tumor cell growth was due to cell apoptosis. The plant extracts at the 100 µg/ml dose induced apoptosis in HeLa (98.5 ± 0.1%) and K562 (57.7 ± 1.9%) cells. The extracts increased caspase 3 activation (≈2-fold>control). Real-time PCR showed Fas and Bax gene upregulation and Bcl-2 downregulation, which resulted in an increased Bax/Bcl-2 expression ratio. The extracts increased lymphocyte proliferation and increased levels of IFN-γ production in the presence and absence of mitogen (p < 0.05). They significantly increased IL-4 and decreased IL-10 secretion by mitogen-stimulated lymphocytes. E. hebecarpa also increased IL-17 release. Conclusion: These results have shown that both extracts possess antitumor activity by inducing apoptosis, possibly through both intrinsic and extrinsic pathways. In addition, they induced secretion of different T helper subset related cytokines that are effective in the immune response against cancer.

Evolutionary prediction of medicinal properties in the genus Euphorbia L.

The current decrease of new drugs brought to the market has fostered renewed interest in plant-based drug discovery. Given the alarming rate of biodiversity loss, systematic methodologies in finding new plant-derived drugs are urgently needed. Medicinal uses of plants were proposed as proxy for bioactivity, and phylogenetic patterns in medicinal plant uses have suggested that phylogeny can be used as predictive tool. However, the common practice of grouping medicinal plant uses into standardised categories may restrict the relevance of phylogenetic predictions. Standardised categories are mostly associated to systems of the human body and only poorly reflect biological responses to the treatment. Here we show that medicinal plant uses interpreted from a perspective of a biological response can reveal different phylogenetic patterns of presumed underlying bioactivity compared to standardised methods of medicinal plant use classification. In the cosmopolitan and pharmaceutically highly relevant genus Euphorbia L., identifying plant uses modulating the inflammatory response highlighted a greater phylogenetic diversity and number of potentially promising species than standardised categories. Our interpretation of medicinal plant uses may therefore allow for a more targeted approach for future phylogeny-guided drug discovery at an early screening stage, which will likely result in higher discovery rates of novel chemistry with functional biological activity.

Comparative study on plant latex particles and latex coagulation in Ficus benjamina, Campanula glomerata and three Euphorbia species.

Among latex-producing plants, mainly the latex of Hevea brasiliensis has been studied in detail so far, while comprehensive comparative studies of latex coagulation mechanisms among the more than 20,000 latex-bearing plant species are lacking. In order to give new insights into the potential variety of coagulation mechanisms, the untreated natural latices of five latex-bearing plants from the families Euphorbiaceae, Moraceae and Campanulaceae were visualised using Cryo-SEM and their particle size compared using the laser diffraction method. Additionally, the laticifers of these plants species were examined in planta via Cryo-SEM. Similar latex particle sizes and shape were found in Ficus benjamina and Hevea brasiliensis. Hence, and due to other similarities, we hypothesize comparable, mainly chemical, coagulation mechanisms in these two species, whereas a physical coagulation mechanism is proposed for the latex of Euphorbia spp. The latter mechanism is based on the huge amount of densely packed particles that after evaporation of water build a large surface area, which accelerates the coagulation procedure.

Evolutionary bursts in Euphorbia (Euphorbiaceae) are linked with photosynthetic pathway.

The mid-Cenozoic decline of atmospheric CO2 levels that promoted global climate change was critical to shaping contemporary arid ecosystems. Within angiosperms, two CO2 -concentrating mechanisms (CCMs)-crassulacean acid metabolism (CAM) and C4 -evolved from the C3 photosynthetic pathway, enabling more efficient whole-plant function in such environments. Many angiosperm clades with CCMs are thought to have diversified rapidly due to Miocene aridification, but links between this climate change, CCM evolution, and increased net diversification rates (r) remain to be further understood. Euphorbia (∼2000 species) includes a diversity of CAM-using stem succulents, plus a single species-rich C4 subclade. We used ancestral state reconstructions with a dated molecular phylogeny to reveal that CCMs independently evolved 17-22 times in Euphorbia, principally from the Miocene onwards. Analyses assessing among-lineage variation in r identified eight Euphorbia subclades with significantly increased r, six of which have a close temporal relationship with a lineage-corresponding CCM origin. Our trait-dependent diversification analysis indicated that r of Euphorbia CCM lineages is approximately threefold greater than C3 lineages. Overall, these results suggest that CCM evolution in Euphorbia was likely an adaptive strategy that enabled the occupation of increased arid niche space accompanying Miocene expansion of arid ecosystems. These opportunities evidently facilitated recent, replicated bursts of diversification in Euphorbia.

Phytochemical relationship of Euphorbia helioscopia and Euphorbia pulcherrima with Lactuca sativa.

Allelopathy is an important phenomenon that modifies the ecosystem. A plant can enhance or reduce the growth of other plant due to the presence of a number of allelochemicals in its different parts. Euphorbia helioscopia and Euphorbia pulcherrima are medicinal plant species. Both these species are collected from wild resources for various purposes. To reduce the pressure on wild population, it is important to bring them into cultivation. Therefore, the allelopathic effects of E. helioscopia and E. pulcherrima on the growth of lettuce seeds were studied. Three different concentrations (2%, 4% and 6%) of five different solvents (methanol, acetone, ethyl acetate, n-hexane and distilled water) were used to estimate the allelopathic potential of the above-mentioned Euphorbia species. Results indicated a non-significant growth inhibitory effect of both plants on lettuce seeds. Different extracts reduced the growth of test plant to some extent but this inhibition was not significant. From the observed results, it was concluded that the studied Euphorbia species, being medicinally important crops, can be introduced as intercrop with other cash crops.

Insights on the evolution of plant succulence from a remarkable radiation in Madagascar (Euphorbia).

Patterns of adaptation in response to environmental variation are central to our understanding of biodiversity, but predictions of how and when broad-scale environmental conditions such as climate affect organismal form and function remain incomplete. Succulent plants have evolved in response to arid conditions repeatedly, with various plant organs such as leaves, stems, and roots physically modified to increase water storage. Here, we investigate the role played by climate conditions in shaping the evolution of succulent forms in a plant clade endemic to Madagascar and the surrounding islands, part of the hyper-diverse genus Euphorbia (Euphorbiaceae). We used multivariate ordination of 19 climate variables to identify links between particular climate variables and three major forms of succulence-succulent leaves, cactiform stem succulence, and tubers. We then tested the relationship between climatic conditions and succulence, using comparative methods that account for shared evolutionary history. We confirm that plant water storage is associated with the two components of aridity, temperature, and precipitation. Cactiform stem succulence, however, is not prevalent in the driest environments, countering the widely held view of cactiforms as desert icons. Instead, leaf succulence and tubers are significantly associated with the lowest levels of precipitation. Our findings provide a clear link between broad-scale climatic conditions and adaptation in land plants, and new insights into the climatic conditions favoring different forms of succulence. This evidence for adaptation to climate raises concern over the evolutionary future of succulent plants as they, along with other organisms, face anthropogenic climate change.

Euphorbia tirucalli L.-comprehensive characterization of a drought tolerant plant with a potential as biofuel source.

Of late, decrease in mineral oil supplies has stimulated research on use of biomass as an alternative energy source. Climate change has brought problems such as increased drought and erratic rains. This, together with a rise in land degeneration problems with concomitant loss in soil fertility has inspired the scientific world to look for alternative bio-energy species. Euphorbia tirucalli L., a tree with C3/CAM metabolism in leaves/stem, can be cultivated on marginal, arid land and could be a good alternative source of biofuel. We analyzed a broad variety of E. tirucalli plants collected from different countries for their genetic diversity using AFLP. Physiological responses to induced drought stress were determined in a number of genotypes by monitoring growth parameters and influence on photosynthesis. For future breeding of economically interesting genotypes, rubber content and biogas production were quantified. Cluster analysis shows that the studied genotypes are divided into two groups, African and mostly non-African genotypes. Different genotypes respond significantly different to various levels of water. Malate measurement indicates that there is induction of CAM in leaves following drought stress. Rubber content varies strongly between genotypes. An investigation of the biogas production capacities of six E. tirucalli genotypes reveals biogas yields higher than from rapeseed but lower than maize silage.

[Identification of medicinal plants used as Tibetan traditional medicine Chuan-Bu based on nrDNA markers].

OBJECTIVE: To identify the common Tibetan herb Chuan-Bu. METHOD: Local herbalists were visited to observe which plants were being used as Chuan-Bu. Samples of the indigenous plants were collected at the same time. Leaf materials were collected from field surveys. Total genomic DNA was extracted from silica gel-dried leaf samples. The PCR products were purified and directly sequenced. RESULT: As the origin of Chuan-Bu in Tibet autonomous region was authenticated, two species were determined, i. e. Euphorbia stracheyiand E. wallichii. Also, based on our earlier research, the origin of Chuan-Bu in Gansu province, is from E. kansuensis. The sequences of ITS1 for E. stracheyi and E. wallichii were 261 bp in size, and 221 bp in ITS2, respectively. The size of the 5.8S coding region was 164 bp for all species examined in the genus. Especially, there was a heterozygous locus in ITS1 (C/G; position 72) for E. stracheyi. The nucleotide divergence between sequences of the 6 species in pairwise comparisons was calculated and the result showed that the variable site could be detected in each pairwise comparison of sequences. Also, there were 8 point mutations in the 5.8S coding region. CONCLUSION: nrDNA ITS sequences can be used as the molecular markers to identify the Tibetan herb Chuan-Bu and such Traditional Chinese Medicines from the same genus Euphorbia as E. lathyris, E. humifusa and E. pekinensis.

The Caribbean slipper spurge Euphorbia tithymaloides: the first example of a ring species in plants.

A ring species arises when a parental population expands around an area of unsuitable habitat in such a way that when the two fronts meet they behave as distinct species while still being connected through a series of intergrading populations. Ring species offer great possibilities for studying the forces causing species divergence (e.g. the nature of pre-zygotic or post-zygotic reproductive isolation) or helping to maintain species integrity (e.g. reinforcement). Yet, ring species are extremely rare, and have only been documented convincingly in animals. Here, we present phylogenetic analyses of two nuclear gene regions from the Caribbean slipper spurge (Euphorbia tithymaloides) species complex that provide evidence that this group forms a ring species. These data show that the species complex originated in the area where Mexico and Guatemala meet, and expanded around the Caribbean basin along two distinct fronts: one eastward through the Yucatan Peninsula and into the Greater Antilles (GA); one southeastward through northern South America and then northward to the Lesser Antilles and eastern GA. The two terminal forms co-occur in the Virgin Islands and appear to be morphologically and ecologically distinct. Thus, our results suggest that Euphorbia tithymaloides is the first compelling example of a ring species in plants.

Phylogenetics and the evolution of major structural characters in the giant genus Euphorbia L. (Euphorbiaceae).

Euphorbia is among the largest genera of angiosperms, with about 2000 species that are renowned for their remarkably diverse growth forms. To clarify phylogenetic relationships in the genus, we used maximum likelihood, bayesian, and parsimony analyses of DNA sequence data from 10 markers representing all three plant genomes, averaging more than 16kbp for each accession. Taxon sampling included 176 representatives from Euphorbioideae (including 161 of Euphorbia). Analyses of these data robustly resolve a backbone topology of four major, subgeneric clades--Esula, Rhizanthium, Euphorbia, and Chamaesyce--that are successively sister lineages. Ancestral state reconstructions of six reproductive and growth form characters indicate that the earliest Euphorbia species were likely woody, non-succulent plants with helically arranged leaves and 5-glanded cyathia in terminal inflorescences. The highly modified growth forms and reproductive features in Euphorbia have independent origins within the subgeneric clades. Examples of extreme parallelism in trait evolution include at least 14 origins of xeromorphic growth forms and at least 13 origins of seed caruncles. The evolution of growth form and inflorescence position are significantly correlated, and a pathway of evolutionary transitions is supported that has implications for the evolution of Euphorbia xerophytes of large stature. Such xerophytes total more than 400 species and are dominants of vegetation types throughout much of arid Africa and Madagascar.

Phylogenetics of the Chamaesyce clade (Euphorbia, Euphorbiaceae): reticulate evolution and long-distance dispersal in a prominent C4 lineage.

PREMISE OF THE STUDY: The Chamaesyce clade of Euphorbia is the largest lineage of C(4) plants among the eudicots, with 350 species including both narrow endemics and cosmopolitan weeds. We sampled this group worldwide to address questions about subclade relationships, the origin of C(4) photosynthesis, the evolution of weeds, and the role of hybridization and long-distance dispersal in the diversification of the group. • METHODS: Two nuclear (ITS and exon 9 of EMB2765) and three chloroplast markers (matK, rpl16, and trnL-F) were sequenced for 138 ingroup and six outgroup species. Exon 9 of EMB2765 was cloned in accessions with >1% superimposed peaks. • KEY RESULTS: The Chamaesyce clade is monophyletic and consists of three major subclades [1(2,3)]: (1) the Acuta clade, containing three North American species with C(3) photosynthesis and C(3)-C(4) intermediates; (2) the Peplis clade, mostly North American and entirely C(4); and (3) the Hypericifolia clade, all C(4), with both New World and Old World groups. Incongruence between chloroplast and ITS phylogenies and divergent cloned copies of EMB2765 exon 9 suggest extensive hybridization, especially in the Hawaiian Islands radiation. • CONCLUSIONS: The Chamaesyce clade originated in warm, arid areas of North America, where it evolved C(4) photosynthesis. From there, it diversified globally with extensive reticulate evolution and frequent long-distance dispersals. Although many species are weedy, there are numerous local adaptations to specific substrates and regional or island radiations, which have contributed to the great diversity of this group.

Giants and dwarfs: molecular phylogenies reveal multiple origins of annual spurges within Euphorbia subg. Esula.

Euphorbia (Euphorbiaceae) comprises over 2150 species and is thus the second-largest genus of flowering plants. In Europe, it is represented by more than 100 species with highest diversity in the Mediterranean area; the majority of taxa belong to subgenus Esula Pers., including about 500 taxa. The few available phylogenetic studies yielded contrasting results regarding the monophyly of subg. Esula, and the phylogenetic relationships among its constituents remain poorly understood. We have sampled DNA sequences from the nuclear ribosomal internal transcribed spacer (ITS) and the plastid trnT-trnF region from about 100, predominantly European taxa of subg. Esula in order to infer its phylogenetic history. The plastid data support monophyly of subg. Esula whereas the ITS phylogeny, which is generally less resolved, is indecisive in this respect. Although some major clades have partly incongruent positions in the ITS and plastid phylogenies, the taxonomic content of the major terminal clades is congruent in both trees. As traditional sectional delimitations are largely not corroborated, an improved classification is proposed. Character state reconstruction illustrates that the annual life form developed independently several times in different clades of subgenus Esula from perennial ancestors, and that several morphological traits used in previous classifications of Euphorbia developed in parallel in different lineages.