Senecio Research Articles

Anti-tuberculosis Compounds from two Bolivian Medicinal Plants, Senecio Mathewsii and Usnea Florida

Bioassay-directed fractionation of the organic extract of Senecio mathewsii gave four compounds with anti-TB activity: werneria chromene (1), capillarol (2), werneria chromanone (3) and plicatin B (4). All of these are new to the genus Senecio and one of these, werneria chromanone (3), was isolated from a natural source for the first time. With the aid of 2D NMR, revised (1) or new (2–4) spectral assignments were made. Similarly, the major anti-TB activity of Usnea florida was shown to be solely due to usnic acid.

Allergenicity and cross‐reactivity of Senecio pollen: identification of novel allergens using the immunoproteomics approach

The genus Senecio is the largest genus of the family Asteraceae (Compositae). The allergenicity of Senecio has not been assessed previously. The aim of this study was to investigate the allergens of Senecio jacobea pollen and to determine their immunological characteristics and clinical relevance. Fifty patients with rhinoconjunctivitis and a positive skin prick test (SPT) to Senecio were recruited. The clinical relevance of this pollen was assessed by means of a nasal provocation test (NPT). Allergens were characterized by one-dimensional electrophoresis (SDS-PAGE) and two-dimensional gel electrophoresis and immunoblotting. Furthermore, characterization and identification of the allergens were performed by mass spectrometry (MS). In vitro inhibition tests were performed to evaluate cross-reactivity with other pollen. Three predominant allergens, both in the intensity of reaction and the frequency of recognition by human-allergic sera, were 59 (60%), 42 (50%) and 31 kDa (50%). The two-dimensional analysis allowed the identification of several allergens. One spot around 42 kDa was identified as a protein homologous to pectate lyase and three other spots were homologous to malate dehydrogenase by MS. S. jacobea proteins showed cross-reactivity with other proteins of the Asteraceae family and also with Parietaria judaica. This was demonstrated by immunoblotting and ELISA inhibition studies. S. jacobea constitute a newly discovered allergenic source. It shows cross-reactivity with other members of the Asteraceae plant family as well as with P. judaica.

Pyrrolizidine alkaloids from Bulgarian species of the genus Senecio

Nine Bulgarian species from the genus Senecio were studied phytochemically and/or by GC-MS analysis. Senecivernine-N-oxide was isolated and identified by spectral data for the first time. Different types of pyrrolizidine alkaloids were tested for cytotoxicity on murine lymphocytes. At a concentration of 100 ?g/ml, the alkaloid retroisosenine showed immunosuppressive effect. .

Development of anonymous cDNA microarrays to study changes to theSeneciofloral transcriptome during hybrid speciation

Interspecific hybridization is an important process through which abrupt speciation can occur. In recent years, genetic changes associated with hybrid speciation have been identified through a variety of techniques, including AFLP/SSR mapping, GISH/FISH and cDNA-AFLP differential display. However, progress in using microarray technology to analyse whole genome/transcriptome changes associated with hybrid speciation has been limited due to the lack of extensive sequence data for many hybrid species and the difficulties in extrapolating results from commercially available microarrays for model species onto nonmodel hybrid taxa. Increasingly therefore researchers studying nonmodel systems are turning to the development of 'anonymous' cDNA microarrays, where the time and cost of producing microarrays is reduced by printing unsequenced cDNA clones, and sequencing only those clones that display interesting expression patterns. Here we describe the creation, testing and preliminary use of anonymous cDNA microarrays to study changes in floral transcriptome associated with allopolyploid speciation in the genus Senecio. We report a comparison of gene expression between the allohexaploid hybrid, Senecio cambrensis, its parental taxa Senecio squalidus (diploid) and Senecio vulgaris (tetraploid), and the intermediate triploid (sterile) hybrid Senecioxbaxteri. Anonymous microarray analysis revealed dramatic differences in floral gene expression between these four taxa and demonstrates the power of this technique for studies of the genetic impact of hybridization in nonmodel flowering plants.

Frequent gain and loss of pyrrolizidine alkaloids in the evolution of Senecio section Jacobaea (Asteraceae)

Pyrrolizidine alkaloids (PAs) of the macrocyclic senecionine type are secondary metabolites characteristic for most species of the genus Senecio (Asteraceae). These PAs are deterrent and toxic to most vertebrates and insects and provide plants with a chemical defense against herbivores. We studied the PA composition of 24 out of 26 species of Senecio section Jacobaea using GC-MS. The PA profiles of eight of these species have not been studied before and additional PAs were identified for most other species that were included in previous studies. With one exception (senecivernine) all 26 PAs identified in sect. Jacobaea can be regarded as derivatives of the biosynthetic backbone structure senecionine. Based on the PA profiles of the species of sect. Jacobaea and the results of previous tracer studies, we constructed two hypothetical biosynthetic scenarios of senecionine diversification. Both scenarios contain two major reactions: the conversion of the necine base moiety retronecine into the otonecine moiety and site-specific epoxidations within the necic acid moiety. Further reactions are site-specific hydroxylations, sometimes followed by O-acetylations, site-specific dehydrogenations, E, Z-isomerizations, and epoxide hydrolysis and chlorolysis. The GC-MS data and both biosynthetic scenarios were subsequently used to study the evolution of PA formation in sect. Jacobaea by reconstructing the evolutionary history of qualitative PA variation in this section. This was achieved by optimizing additive presence/absence data of PAs and types of enzymatic conversions on a maximum parsimony cladogram of section Jacobaea inferred from DNA sequence and morphological data. Besides showing large intra- and interspecific variation, PA distribution appears to be largely incidental within the whole clade. These results together with the finding that all but one of the PAs identified in sect. Jacobaea are also present in species of other sections of Senecio indicate that differences in PA profiles in Senecio can not be explained by the gain and loss of PA specific genes, but rather by a transient switch-off and switch-on of the expression of genes encoding PA pathway-specific enzymes.

INFLUENCE OF LIGHT ON THE GERMINATION OF RAGWORT (Senecio jacobaea L., Asteraceae) SEEDS PREVIOUSLY STORED IN THE SOIL SEED BANK OF A PASTURE

An experiment was carried out to determine the effect of light on the germination of ragwort (Senecio jacobaea L.) seeds found in the soil seed bank of a cultivated perennial pasture of temperate species. Previous studies used seeds drawn from seed heads, which may not represent the actual physiological conditions of seeds found in the soil. Thus, soil containing ragwort seeds was extracted in the dark (150 soil samples, 2.6cm in diameter, 0-2cm deep) from a dairy pasture and left in plastic pots within two growth cabinets kept either in the dark (scotophase) or in constant light (photophase) conditions at 20oC. Seed germination, assessed through seedling emergence, was four times larger in the light than in the dark, totalling 55.6% and 13.9%, respectively. Of particular interest was the germination in the dark, which suggests that the active form of phytochrome is stable in ragwort seeds. These results are discussed on the basis of the knowledge of phytochrome activity. It is concluded that ragwort germination is positively affected by the presence of unfiltered light and it is argued that, in field conditions, germination would not take place in the dark.

Distributional modelling and parsimony analysis of endemicity of Senecio in the Mediterranean‐type climate area of Central Chile

AbstractAim Floristic blocks and areas of endemism resulting from a parsimony analysis of endemicity (PAE) using raw floristic data versus data generated from distributional modelling for 130 species in the genus Senecio Tourn. ex L. distributed in the Mediterranean‐type climate area of Central Chile were compared, and the results were used to identify conservation priorities for the flora of the region.Location Central Chile, between 30° and 38° S.Methods Using herbarium records, a species × area matrix consisting of presence/absence data was constructed from a 0.5° × 0.5° grid. Distributional modelling techniques incorporating vegetation formations, elevation and the contagion index were used to interpolate floristic composition of poorly known areas. Parsimony analysis of endemicity was used to identify floristic blocks and areas of endemism.Results Using the number of most parsimonious trees as an index, distributional modelling greatly optimized the results of the PAE analysis. Three floristic blocks and four areas of endemism were suggested based on the PAE results using potential distribution data not incorporating the contagion index, while four blocks and two areas of endemism were suggested from the PAE results using potential distribution data incorporating the contagion index. Floristic blocks for the northern coast, southern Andes, and northern/central Andes were found, with some blocks showing divisions within them representing distinct geographic subunits. Major breaks between and within floristic blocks were identified at 32.5°–33° S and 34.5°–35° S.Main conclusions The floristic blocks identified with the distributional modelling and PAE correspond well to results from some previous studies and support hypothesized biogeographic divisions within Central Chile. The results were similar to those obtained from parallel analysis of the entire tree flora of Central Chile. The vegetative formation‐based distributional modelling produced robust and reproducible results when used along with PAE, especially when the contagion index was incorporated, and is a useful technique for area classification. The results demonstrate the utility of Senecio as an indicator genus for biogeography and conservation in southern South America.

Floristics of the Dunbar Valley serpentinite site, Songimvelo Game Reserve, South Africa

The Dunbar Valley serpentinite outcrop has a flora comprising 254 taxa (species and below) in 172 genera and 63 families. Dunbar Valley has more species than other studied serpentinite sites in the Barberton Greenstone Belt (BGB). The genus Senecio is the most speciose genus in the BGB. The level of species endemism at Dunbar Valley is 2.0%. Most of the serpentinite endemics in the BGB show phytogeographical affinities with the Sudano-Zambezian Region. Six modified-Whittaker plots, three on serpentinite and three on non-serpentinite soils, were sampled. Sorenson's index was 0.312, indicating low similarity in species between serpentinite and non-serpentinite sites (β-diversity) at Dunbar Valley, as at other sites in the BGB. α-diversity (using the Shannon–Wiener index) for the serpentinite was 2.631 ± 0.901 and for the non-serpentinite, 2.886 ± 0.130. However, a Student's t-test showed no significant difference in α-diversity between the two habitats. There was also no significant difference in species richness between serpentinite and non-serpentinite sites. Total species showed negative correlations with total nickel, altitude and serpentinite outcrop size (area) for six sites in the BGB. Number of endemic taxa showed no correlation with environmental variables. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 143, 271–285.

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.

First Report of the Presence of Albugo tragopogonis on Cineraria maritima in Italy.

Cineraria maritima L. (synonym Senecio cineraria DC.), commonly known as dusty-miller, is grown in Italy for landscape use in parks and gardens. In the spring of 2001, severe outbreaks of a previously unknown disease were observed in commercial farms located in northern Italy. Leaves of infected plants showed several sori on the abaxial surface, progressing to the adaxial surface, and often in the interveinal areas. On the adaxial surface of leaves, chlorotic areas developed and eventually turned brown. Severely infected leaves wilted, but remained attached to the stem. Signs of the fungus were present as whitish and catenulate sporangia emerging from the sori. Sporangia, organized in chains, had an average diameter of 20.5 × 26.5 μm. On the basis of the microscopic observations, the causal agent of the disease was identified as Albugo tragopogonis. Pathogenicity was confirmed by inoculating leaves of healthy C. maritima plants with a sporangial suspension (5 × 102 sporangia per ml) obtained from infected plants. Noninoculated plants served as a control. Plants were kept covered with plastic bags for 72 h and maintained at 15°C. After 10 days, typical symptoms of white rust developed on inoculated plants starting from the basal leaves. Within 30 days, affected leaves were completely wilted. Microscopic examination of sporangia within sori verified the pathogen to be A. tragopogonis. No symptoms developed on the control plants. A. tragopogonis has been reported as the causal agent of white rust on several species belonging to the genus Senecio in the United States (1). In New Zealand, the presence of A. tragopogonis was reported on the genus Cineraria in 1959 (2). To our knowledge, this is the first report of the presence of white rust on Cineraria maritima in Italy.

Inclusão de material herborizado em metacrilato para estudos de anatomia vegetal

As técnicas usuais empregadas no processamento de materiais herborizados são limitantes porque não permitem reproduzir um laminário permanente e porque o registro dos resultados é temporário. Em estudos de anatomia aplicada à taxonomia, muitas vezes, é necessário utilizar exsicatas. Este trabalho teve como objetivo testar a utilização de metacrilato (Historesin, Leica) na preparação e inclusão de material herborizado, visando a obtenção de laminário permanente. Foram utilizadas folhas de plantas herborizadas do gênero Senecio Tourn. ex L. (Asteraceae), previamente reidratadas em H2O e armazenadas em etanol 70%. As amostras foram desidratadas em série etanólica e submetidas à (1v:1v) mistura de AE 95% e resina pura. Durante a infiltração, com resina pura, o material foi submetido a vácuo durante 72 horas. Os blocos foram cortados em micrótomo de avanço automático, com navalhas de aço descartáveis, e os cortes foram corados com azul-de-toluidina (pH 4,0). As lâminas foram montadas em Permount. O laminário permanente obtido apresentou qualidade superior à dos produzidos pelas técnicas usuais, pois foi possível obter cortes seriados, com espessura determinada. Essa técnica possibilitou otimizar a obtenção de cortes, a partir de pequenos fragmentos de exsicatas.

Synthesis OF (1 R ,2 R ,7 R ,7a S )-1-Hydroxymethyl-2,3,5,6,7,7a-Hexahydropyrrolizidine-1,2,7-TRIOL from Rosmarinine Degradation

A novel tetrahydroxypyrrolizidine alkaloid ( 6 ) was obtained from rosmarinine degradation in 23% yield (isolated from Senecio callosus )

Pyrrolizidine alkaloids as oviposition stimulants for the cinnabar moth, Tyria jacobaeae.

In choice experiments with artificial leaves, we tested related pyrrolizidine alkaloids (PAs) for their stimulatory effects on the oviposition of the cinnabar moth, a specialist on the PA-containing plant Senecio jacobaea. The PAs from S. jacobaea that we tested stimulated oviposition. Monocrotaline also stimulated oviposition although this PA is not found in plants of the genus Senecio. The moths preferred ovipositing on filter paper with a PA mixture extracted from S. jacobaea to ovipositing on filter paper with single PAs. Senkirkine, heliotrine, and retrorsine did not stimulate oviposition. The nonactive retrorsine differs only in one OH group to the active senecionine, indicating that small structural differences alter the stimulatory activity of PAs. However, a PA mixture extracted from a nonhost plant, Senecio inaequidens, that consisted of 81% of the nonactive retrorsine did stimulate oviposition. Oviposition preferences between Senecio species seem to be determined by chemical compounds other than PAs.

Packera lyallii, a Corrected Name for Packera contermina (Asteraceae: Senecioneae)

The new combination Packera lyallii (Klatt) J. F. Bain is proposed, based on Senecio lyallii Klatt.

Development of enzyme-linked immunosorbent assays for the hepatotoxic alkaloids riddelliine and riddelliine N-oxide.

Pyrrolizidine alkaloid-containing plants are widely distributed throughout the world and are particularly common in the genus Senecio. The structural types and concentrations of the alkaloids vary among plant species. In addition, within a species of plant, concentrations vary with environment and location. Many pyrrolizidine alkaloids are toxic and cause poisoning in livestock and in humans. Rapid, sensitive, and specific diagnostic techniques are needed to identify poisoned animals and to determine the particular plants and conditions under which livestock are likely to be poisoned. In this study, two competitive inhibition enzyme-linked immunosorbent assays for riddelliine, riddelliine N-oxide, and other closely related pyrrolizidine alkaloids were developed using polyclonal antibodies. One assay is class specific toward the free base forms of the pyrrolizidine alkaloids; the other assay showed cross-reactivity to both the free base and N-oxide forms of the alkaloids. The assay with the lowest limit of detection had an I(50) of 803.9 pg with a limit of detection of 47.5 pg for riddelliine. Spike and recovery studies for riddelliine in bovine blood ranged from 45 to 74%. The assay that showed cross-reactivity between the N-oxide and free base forms of the pyrrolizidine alkaloids allowed estimation of the total pyrrolizidine alkaloid content in Senecio riddellii in admixture with alfalfa. These findings suggest that these techniques will be excellent tools to diagnose poisoned animals and identify highly toxic plants.

Longevity of buried ragwort seed in four soils

The viability of ragwort (Senecio jacobaea L) seed buried for several years at 0 2 4 6 and 19 21 cm depths was evaluated in four different soil types Seed samples in nylon mesh bags were removed after 1 2 3 5 11 and 16 years burial and their viability determined by germination After 16 years no viable seed was found in the clay soil In the silt loam and peat soils 1 3 viable seed remained while in the sandy soil up to 13 remained viable In the surface 0 2 cm layer of soil it took from 109 to 146 years for the percentage of viable seed to fall to 1 of the original viable seed depending on soil type At the 4 6 and 19 21 cm depths the corresponding times were 128 165 years and 130 180 years

The Tribe Senecioneae (Compositae) in Bahia, Brazil, with Descriptions of a New Section and Species in Senecio

A new species of Senecio, S. harleqi, is described and illustrated from the state of Bahia, Brazil. The position of the new taxon within the genus Senecio sensu stricto and its affinity to S. regis is discussed; both are illustrated. A new section of the genus, section Bahiana, is described and its affinities to other sections in subgenus Senecio discussed. A key to the species in the genera of the tribe Senecioneae in Bahia is provided; twelve species and five genera are recognized as occurring in the state.

Estudios cariológicos en Asteraceae. VIII

Meiotic and/or mitotic chromosome numbers were determined and observations on meiotic behavior were made in 14 accessions belonging to 14 especies concerning 8 genera distributed in 4 tribes of the Asteraceae. Five species are investigated chromosomally for the first time. These are as follows, tribe Mutisieae: Brachyclados cespitosus (Phil.) Speg. (n = 23), Nassauvia pygmaea (Cass.) Hooker (n = 22); tribe Cichorieae: Hypochoeris acaulis (Remy) Britton (n = 4,2 n= 8), Hieracium glaucifolium Poepp. ex Froelich in DC. (2n = 18) and Hieracium aff. palezieuxii Zahn (2n = 18). Different chromosome number to those previously reported in the literature were found for Hypochoeris chondrilloides (A. Gray) Cabrera (n = 8), Baccharis ulicina Hook. Am. (2n = 18+3B), Conyza aff. bonariensis (L.) Cronquist (2n = 18). The karyotypes of Brachyclados lycioides Don, Hypochoeris acaulis (Rerny) Britton, Hieracium aff. palezieuxii Zahn and Senecio chilensis Less. are described for the first time. Meanwhile, the karyotypes of Hypochoeris microcephala (Sch. Bip.) Cabrera var. albiflora (Kuntze) Cabrera, H. chillensis (Kunth) Hieron and H. megapotamica Cabrera showed to be slightly different with those described in previous publications. The significance of some of the results in relation to taxonomical and evolutionary problems is discussed.

Pyrrolizidine Alkaloids from Bulgarian Species—Genus Senecio and their Insecticidal Properties

ABSTRACTTen pyrrolidine alkaloids were isolated and identified from three uninvestigated Bulgarian species of genus Senecio. Integerrimine N-oxide was isolated and identified as N-oxide for the first time, while 7—and 9—angeloylplatinecine were proved like base and N-oxide by procedure giving possibility for evaluation of the forms in which they are present in plants. In our research for new natural insecticides an initial study for direct poison effect of some pyrrolizidine alkaloids and total alkaloid mixtures against several pests of economic importance have been conducted. The results showed that retronecine type alkaloids are more toxic than platynecine type. At first high effectiveness of seneciphylline was observed against 0–2 day old greenhouse whitefly's eggs.

Pyrrolizidine Alkaloids of Three Species ofSenecioin British Columbia

A new alkaloid, 9- O-acetyl-7- O-angelyl-retronecine, was isolated from Senecio triangularis together with 7-O-angelyl-, 9-O-angelyl-, and 7-O-angelyl-9-O-sarracinylretronecine; S. pseudaureus and S. streptanthifolios yielded only retrorsine and senecionine.