Afro-alpine flagships revisited: Parallel adaptation, intermountain admixture and shallow genetic structuring in the giant senecios (Dendrosenecio).

Distantly related lineages of the enigmatic giant rosette plants of tropical alpine environments provide classical examples of convergent adaptation. For the giant senecios (Dendrosenecio), the endemic landmarks of the East African sky islands, it has also been suggested that parallel adaptation has been important for within-lineage differentiation. To test this hypothesis and to address potential gene flow and hybridization among the isolated sky islands, we organized field expeditions to all major mountains. We sampled all currently accepted species and all but one subspecies and genotyped 460 plants representing 109 populations. We tested whether genetic structuring corresponds to geography, as predicted by a parallel adaptation hypothesis, or to altitudinal belt and habitat rather than mountains, as predicted by a hypothesis of a single origin of adaptations. Bayesian and Neighbor-Net analyses showed that the main genetic structure is shallow and largely corresponds to geography, supporting a hypothesis of recent, rapid radiation via parallel altitude/habitat adaptation on different mountains. We also found evidence for intermountain admixture, suggesting several long-distance dispersals by wind across vast areas of unsuitable habitat. The combination of parallel adaptation, secondary contact, and hybridization may explain the complex patterns of morphological variation and the contradicting taxonomic treatments of these rare enigmatic giants, supporting the use of wide taxonomic concepts. Notably, the within-population genetic diversity was very low and calls for increased conservation efforts.

A study of the phytotoxic effects of the aerial parts of Senecio westermanii Dusén (Asteraceae) on Lactuca sativa L. and Allium cepa L. seeds

The objective of this study was to evaluate the effects of the ethanolic crude extracts and fractions of the species Senecio westermanii Dusén on Lactuca sativa L. (lettuce) and Allium cepa L. (onion) seeds. We assessed the germination, growth, root respiration and photosynthesis of the target species in Petri dishes (9.0 cm diameter) containing filter paper n°6. The study was conducted using 50 seeds per plate and held in 4 replicates per concentration of each sample. In the germination there was an inhibitory effect of fractions hexane (FH) and chloroform (FCl) at concentrations of 500 and 1000 µg/mL. There was a reduction in the radicle growth of lettuce by 14 to 24% and a reduction of hypocotilum by 14 to 28%. As for the radicle of the onion was up 74% reduction to the FCl and the coleoptile was 24 and 45% reduction for FH and FCl, respectively. Inhibitory effects in the root respiration of lettuce were detected in all the samples analyzed, with results ranging from 16 to 83%. For the seeds of A. cepa, there was an encouragement for the FCl and ethyl acetate fractions (FAE), with results ranging from 94 to 142% and 76 to 150%, respectively. With regard to the photosynthesis of L. sativa, there was no significant difference between the control, and as for the A. cepa, there was a strain in inhibition concentrations of 250 and 500 µg/mL, which ranged from 27 to 68%. The samples of S. westermanii caused changes in the target species and thus can be used as a natural herbicide.

Frequent colonization and little in situ speciation in Senecio in the tropical alpine-like islands of eastern Africa.

PREMISE OF THE STUDY: Floras of continental habitat islands, like those of islands, originate mostly through colonization, which can be followed by in situ speciation. We here address the question of the relative importance of colonization and in situ diversification in the high-altitude areas of the eastern African high mountains, the tropical Afroalpine Region, using the most species-rich genus in the region, Senecio, as an example. METHODS: We expanded earlier Senecioneae phylogenies by adding more tropical African species and analyzed our phylogenetic tree biogeographically. KEY RESULTS: Senecio contains at least five clades with tropical African species, all of them containing tropical afroalpine species. Between four to 14 independent colonization events into the tropical Afroalpine most likely from montane regions in southern Africa were found. Additionally, relationships of tropical afroalpine species to Palearctic and South American taxa were identified. Although some in situ diversification occurred in Senecio in the tropical Afroalpine, the resulting number of species per clade is never higher than seven. CONCLUSION: Like other genera, Senecio colonized the tropical Afroalpine several times independently. Comparison with Mt. Kinabalu, a small tropical alpine-like region in Southeast Asia, and alpine-like regions in the Andes implies that rates of in situ speciation might be linked to area size.

Senecio changii (Asteraceae: Senecioneae), a New Species from Sichuan, China.

Senecio changii (Asteraceae: Senecioneae), a new species from Muli, Sichuan, southwestern China, is described. It is distinguished in Chinese Senecio s.s. by having lyrate-pinnatisect to pinnatisect leaves and a single terminal large discoid capitulum which is somewhat nodding. Evidence from floral micromorphology, karyology and molecular phylogenetic analyses based on the nuclear ITS/ETS sequence data all support its membership within Senecio s.s.

Comparison of the anti-inflammatory active constituents and hepatotoxic pyrrolizidine alkaloids in two Senecio plants and their preparations by LC-UV and LC-MS.

Two Senecio plants, Senecio cannabifolius Less. and its variety S. cannabifolius Less. var. integrifolius (Kiodz.) Kidam., were both used as the raw material of Feining granule, a traditional Chinese medicine product for treating respiratory diseases. In this study, the chemical profiles of these two plants were investigated and compared by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR). A total number of 83 constituents, including 55 organic acids, 11 flavonoids, 4 alkaloids, 3 terpenes and 10 other types of compounds, were characterized. The results indicated that the levels of most flavonoids were higher in S. cannabifolius than in S. cannabifolius var. integrifolius, however, the levels of hepatotoxic pyrrolizidine alkaloids (PAs) were higher in S. cannabifolius var. integrifolius than in S. cannabifolius. Fifteen constituents were evaluated on lipopolysaccharides (LPS) induced RAW 264.7 cells, and eleven of them showed inhibition effect against nitric oxide (NO) production. Finally, the levels of ten major constituents (including seven anti-inflammatory active ones) and two PAs in Feining granule from two Senecio plants were determined and compared by the LC-UV and LC-MS methods, respectively. It was found that one organic acid (homogentisic acid) and two PAs (seneciphylline and senecionine) had higher contents in the preparation of S. cannabifolius var. integrifolius than in that of S. cannabifolius, however, the situations were inverse for the levels of four organic acids and flavonoids (chlorogenic acid, hyperoside, isoquercitrin, and isochlorogenic acid B). Based on the above results, S. cannabifolius might be a better raw material for Feining granule than S. cannabifolius var. integrifolius, because it contained more anti-inflammatory constituents and less hepatotoxic PAs than the latter. However, more pharmacological evaluations should be carried out to support the selection. The results in this study were helpful for the quality control of Feining granule.

(Un)targeted metabolomics in Asteraceae: probing the applicability of essential-oil profiles of senecio L. (Senecioneae) taxa in chemotaxonomy.

The possible applicability of (un)targeted metabolomics (volatile metabolites) for revealing taxonomic/evolutionary relationships among Senecio L. species (Asteraceae; tribe Senecioneae) was explored. Essential-oil compositional data of selected Senecio/Senecioneae/Asteraceae taxa (93 samples in total) were mutually compared by means of multivariate statistical analysis (MVA), i.e., agglomerative hierarchical clustering and principal component analysis. The MVA input data set included the very first compositional data on the essential oil extracted from the aerial parts of S. viscosus L. as well as on four different Serbian populations of S. vernalis Waldst. & Kit. (oils from aerial parts and roots; eight samples in total). This metabolomic screening of Senecio/Senecioneae/Asteraceae species (herein presented results and data from the literature) pointed to short-chain alk-1-enes (e.g., oct-1-ene, non-1-ene, and undec-1-ene), with up to now restricted general occurrence in Plantae, as characteristic chemotaxonomic markers/targets for future metabolomic studies of Senecio/Senecioneae taxa. The MVA additionally showed that the evolution of the terpene metabolism (volatile mono- and sesquiterpenoids) within the Asteraceae tribe Senecioneae was not genera specific. However, the MVA did confirm plant-organ specific production/accumulation of volatiles within S. vernalis and suggested the existence of at least two volatile chemotypes for this species.

Genomic divergence during speciation driven by adaptation to altitude.

Even though Darwin's "On the Origin of Species" implied selection being the main driver of species formation, the role of natural selection in speciation remains poorly understood. In particular, it remains unclear how selection at a few genes can lead to genomewide divergence and the formation of distinct species. We used a particularly attractive clear-cut case of recent plant ecological speciation to investigate the demography and genomic bases of species formation driven by adaptation to contrasting conditions. High-altitude Senecio aethnensis and low-altitude S. chrysanthemifolius live at the extremes of a mountain slope on Mt. Etna, Sicily, and form a hybrid zone at intermediate altitudes but remain morphologically distinct. Genetic differentiation of these species was analyzed at the DNA polymorphism and gene expression levels by high-throughput sequencing of transcriptomes from multiple individuals. Out of ≈ 18,000 genes analyzed, only a small number (90) displayed differential expression between the two species. These genes showed significantly elevated species differentiation (FST and Dxy), consistent with diversifying selection acting on these genes. Genomewide genetic differentiation of the species is surprisingly low (FST = 0.19), while ≈ 200 genes showed significantly higher (false discovery rate < 1%; mean outlier FST > 0.6) interspecific differentiation and evidence for local adaptation. Diversifying selection at only a handful of loci may be enough for the formation and maintenance of taxonomically well-defined species, despite ongoing gene flow. This provides an explanation of why many closely related species (in plants, in particular) remain phenotypically and ecologically distinct despite ongoing hybridization, a question that has long puzzled naturalists and geneticists alike.

Extensive range persistence in peripheral and interior refugia characterizes Pleistocene range dynamics in a widespread Alpine plant species (Senecio carniolicus, Asteraceae).

Recent evidence suggests that survival of arctic-alpine organisms in peripheral or interior glacial refugia are not mutually exclusive and may both be involved in shaping an organism's Pleistocene history, yet potentially at different time levels. Here, we test this hypothesis in a high-mountain plant (diploid lineage of Senecio carniolicus, Asteraceae) from the Eastern European Alps, in which patterns of morphological variation and current habitat requirements suggest survival in both types of refugia. To this end, we used AFLPs, nuclear and plastid DNA sequences and analysed them, among others, within a graph theoretic framework and using novel Bayesian methods of phylogeographic inference. On the basis of patterns of genetic diversity, occurrence of rare markers, distribution of distinct genetic lineages and patterns of range connectivity both interior refugia in the formerly strongly glaciated central Alps and peripheral refugia along the southern margin of the Alps were identified. The presence of refugia congruently inferred by markers resolving at different time levels suggests that these refugia acted as such throughout several glacial cycles. The high degree of range persistence together with gradual range expansion, which contrasts with the extent of range shifts implied for other Alpine species, is likely responsible for incipient lineage differentiation evident from the genetic data. Replacing a simplistic peripheral vs. interior refugia dualism by more complex models involving both types of refugia and considering different time levels will help identifying common phylogeographic patterns with respect to, for instance, location of refugia and colonization routes and elucidating their underlying genetic and/or ecological causes. DNA sequences have been deposited in GenBank under accession nos. FR796701­FR797793 and nos. HE614296­HE614583.

The genetic ghost of an invasion past: colonization and extinction revealed by historical hybridization in Senecio.

Hybridization is an important evolutionary factor in the diversification of many plant and animal species. Of particular interest is that historical hybridization resulting in the origin of new species or introgressants has occurred between species now geographically separated by great distances. Here, we report that Senecio massaicus, a tetraploid species native to Morocco and the Canary Islands, contains genetic material of two distinct, geographically separated lineages: a Mediterranean lineage and a mainly southern African lineage. A time-calibrated internal transcribed spacer phylogeny indicates that the hybridization event took place up to 6.18 Ma. Because the southern African lineage has never been recorded from Morocco or the Canary Islands, we hypothesize that it reached this area in the distant past, but never became permanently established. Interestingly, the southern African lineage includes S. inaequidens, a highly invasive species that has recently become widespread throughout Europe and was introduced at the end of the 19th century as a 'wool alien'. Our results suggest that this more recent invasion of Europe by S. inaequidens represents the second arrival of this lineage into the region.

[Macroscopic and microscopic identification of Chinese herb belonging to genus Senecio].

The medicinal herbs derived from genus Senecio have been commonly used in Chinese medicine and triggered attention in recent decades for that they contain the hepatotoxic pyrrolizidine alkaloids. Therefore the botanical pharmacognostic study to authenticate those herbs based on their macroscopic and microscopic characteristics is important for the assurance of safety when they are applied as raw material for extracts or for finished products. In this paper, 13 taxa (11 species and 2 varieties) of Senecio plants were collected and their macroscopic and microscopic characteristics were observed and described by digital microscopic illustration. The results showed that the distribution of collenchyma in the cortex, the level of development for pericycle, the location of the phloem, and the ratio of pith in transverse sections of the stems, and the morphology of the leaf epidermal cells, the stomatal types and the non-glandular hairs in leaf surface view were found to be the main microscopic characteristics for authentication of different Senecio species. The herbs derived from genus Senecio can be distinguished from each other on the basis of their macroscopic and microscopic characteristics, and those observation can be used for the identification of commercial crude drugs from Senecio plants.

Authentication of Senecio scandens and S. vulgaris based on the comprehensive secondary metabolic patterns gained by UPLC-DAD/ESI-MS.

A secondary metabolic pattern using ultra-performance liquid chromatography (UPLC)-DAD/ESI-MS was constructed to gain chemical information for authentication of Senecio scandens (SS) and Senecio vulgaris (SV), the two representative species containing hepatotoxic pyrrolizidine alkaloids (HPAs). The metabolic pattern showed three groups of bioactive constituents: phenolic/aromatic acids, flavonoid glycosides and the HPAs. 47 peaks were identified including 19 phenolic/aromatic acids, 10 flavonoid glycosides and 18 PAs by direct comparison with the available reference compounds or deduced from the UV absorption and their ESI-MS fragmentation patterns. The two species could be authenticated diagnostically by their metabolic profiling of the three chromatographic fingerprints. Although both SS and SV contain PAs as the characteristic constituents, only 2 PAs, adonifoline and adonifoline N-oxide were detected in SS, while other 16 PAs were detected in SV, including the highly toxic senecionine, retrorsine, seneciphylline and their corresponding N-oxides. The concentration of PAs in SV is also higher than that in SS. The number and concentration of the phenolic compounds in SS were higher than in SV. Jacaranone derivatives were only detected in SS and jacaranone ethyl ester was detected as the predominant constituent. In the fingerprint of the n-butanol extracts, 10 quercetin and kaempferol glycosides derivatives were detected. 9 were found in SS and only 2 in SV. PAs, jacaranone derivatives and flavonoid glycosides can serve as the metabolic markers to distinguish the Senecio plants from each other, and provide evidence for their clinical application in the consideration of safety and efficacy.

Pyrrolizidine alkaloid-containing toxic plants (Senecio, Crotalaria, Cynoglossum, Amsinckia, Heliotropium, and Echium spp.).

Pyrrolizidine alkaloid (PA)-containing plants are found throughout the world and are probably the most common plant cause of poisoning of livestock, wildlife, and humans. PAs are potent liver toxins that under some conditions can be carcinogenic. This article briefly introduces high-risk North American PA-containing plants, summarizing their toxicity and subsequent pathology. Current diagnostic techniques, treatments, and strategies to avoid losses to PA poisoning are also reviewed.

Characterisation of sunflower-21 (SF21) genes expressed in pollen and pistil of Senecio squalidus (Asteraceae) and their relationship with other members of the SF21 gene family.

Two related flower-expressed gene copies belonging to the SF21 (sunflower-21) gene family have been isolated from Senecio squalidus (Oxford Ragwort, Asteraceae). These gene copies are differentially expressed in pollen and pistil tissues; ORSF21B (Oxford Ragwort SF21B) is expressed exclusively in mature pollen, whereas ORSF21A (Oxford Ragwort SF21A) is expressed in the transmitting tissue of the style, where it is developmentally regulated. Despite differences in expression, the coding regions of ORSF21A and ORSF21B are highly similar. Amino acid sequence alignments of SF21 genes from a number of angiosperm species indicate that this gene family is conserved in flowering plants and may play an important role in reproductive processes in a wide range of taxa. Phylogenetic analysis of SF21 nucleotide sequence alignments supports this theory, and indicates a complicated history of evolution of this gene family in angiosperms. The putative roles of SF21 genes in reproduction and pollen-pistil interactions are discussed.

Pyrrolizidine alkaloid profiles of the Senecio cineraria group (Asteraceae).

Alkaloid profiles of five Senecio species (Asteraceae), including S. ambiguus subsp. ambiguus, S. ambiguus subsp. nebrodensis, S. gibbosus subsp. bicolor, S. gibbosus subsp. gibbosus, and S. gibbosus subsp. cineraria, were studied. Eleven pyrrolizidine alkaloids were identified and their content was evaluated by GLC-MS and GLC analysis. Otosenine and florosenine were found to be the major alkaloids in all studied species. It is interesting that only S. ambiguus subsp. nebrodensis was characterized by a high content of the alkaloids jacobine, jacoline, jaconine, and jacozine.

Population decline despite high genetic diversity in the new allopolyploid species Senecio cambrensis (Asteraceae).

Senecio cambrensis (Welsh groundsel) is a new allohexaploid species, which originated in Wales, UK, in the early part of the 20th century following hybridization between the native tetraploid groundsel (Senecio vulgaris) and the introduced diploid Oxford ragwort (Senecio squalidus). A survey of the number of populations and flowering individuals per population of S. cambrensis in Wales was conducted at peak flowering time in June 2002, 2003 and 2004. The results show a dramatic decrease in both population number and population size of the species since the 1980s when the last population census was conducted. A survey of amplified fragment length polymorphism (AFLP) variation showed that this decline has occurred despite the fact that S. cambrensis contains a high level of genetic diversity with each individual screened possessing a unique multilocus phenotype. The level of variance within the species was similar to that found in one parent (S. vulgaris) and slightly greater than that among samples of the other parent (S. squalidus). Only a small proportion (5%) of AFLP diversity was partitioned among populations indicating a lack of population structure and possibly high levels of gene flow via seed dispersal in what is predominantly a selfing species. Senecio cambrensis showed closer similarity in AFLP phenotype to S. vulgaris than to S. squalidus. Possible causes of this and also the high level of AFLP diversity found in S. cambrensis are discussed. It is suggested that intergenomic recombination following occasional multivalent formation during meiosis in S. cambrensis is likely to be an important cause of both phenomena, although other causes are not ruled out.

[General situation of the toxicity researches on Senecio].

This article summarized the toxic components, toxication faeature and mechanism and clinical poisoning reports of Senecio spp. The distribution of major toxic components pyrrolizidine alkaloids (PAs) in Chinese medicinal herbs and the application of Senecio spp. in China were also recapitulated. The proposals for the application and development of Senecio spp. were put forward.

Estudio taxonómico del grupo de especies Solanum confine de la sección Geminata (solanaceae) / Taxonomic study of the group of species Solanum confine of the section Geminata (Solanaceae)

La Sección Geminata es una de las más grandes del género Solanum, incluyendo un total de 126 especies que han sido separadas en 16 grupos, de los cuales 12 están representados en Venezuela con 35 especies. El objetivo de este trabajo fue hacer la revisión taxonómica de las especies S. capillipes, S. dissimile, S. erosomarginatum, S. ombrophilum y S. tenuiflagellatum pertenecientes al Grupo de Especies Solanum confine y presentes en Venezuela. Se utilizó material fresco y de los herbarios HERZU, MER, MERF, MO, MY, PORT, US y VEN, procesado para su estudio según las técnicas taxonómicas convencionales. Se incluye descripción, distribución geográfica, hábitat e ilustración de cada una de las especies, asimismo se ofrece una clave para las especies registradas.

The Section Geminata is one of the biggest of the genus Solanum, including a total of 126 species that have beenseparated in 16 groups of which 12 are represented in Venezuela with 35 species. The objective of this work was to make the taxonomic revision of the species S. capillipes, S. dissimile, S. erosomarginatum, S. ombrophilum and S. tenuiflagellatum belonging to the Group of Species Solanum confine and present in Venezuela. Fresh material was used and dried belonging to the herbaria HERZU, MER, MERF, MO, MY, PORT, US and VEN, processed for its study according to the taxonomic conventional technical. Description, geographical distribution, habitat and illustration of each one of the species is included, also a key for the registered species.

Alkaloid profile of Bulgarian species from genus Senecio L.

Twenty-seven pyrrolizidine alkaloids were identified by a detailed phytochemical study and GC/MS analysis on twelve Bulgarian species from genus Senecio. Twenty of them are new for the corresponding species. Other six structures remain tentatively identified.

Pyrrolizidine alkaloids from Senecio jacobaea affect fungal growth.

We investigated the growth-reducing effects of pyrrolizidine alkaloids (PAs) from Senecio jacobaea on nine plant-associated fungi (five strains of Fusarium oxysporum, two of F. sambucinum, and two of Trichoderma sp). Fungal growth was monitored on water agar media containing different concentrations of monocrotaline, retrorsine, or a purified extract of PAs from S. jacobaea. The growth rate of six strains was inhibited by PAs at the highest test concentration (3.33 mM), with the magnitude of the inhibition (7-35%) being dependent upon the specific fungus-PA interaction. In general, the PA extract caused the largest inhibition. However, the fungi isolated from S. jacobaea were positively affected by the PA extract (7-9%). Retrorsine N oxide was as effective as retrorsine in its inhibition of mycelium growth.

Extinction of the Edinburgh lineage of the allopolyploid neospecies, Senecio cambrensis Rosser (Asteraceae).

Senecio cambrensis is a new allopolyploid species, which originated independently in North Wales and in Edinburgh, Scotland. Despite extensive searches, the species has not been found growing at any of its previously recorded sites in Edinburgh or at other potential sites in the area since 1993. We have concluded that the Edinburgh lineage of S. cambrensis is now extinct and discuss possible causes of its extinction. The lineage was present in Edinburgh from at least 1974 and therefore survived in the wild for a minimum of 19 years. The species remains well established in parts of North Wales.