The present paper present a taxonomic study of the Brazilian species of the genus Aspilia Thou. (Compositae-Heliantheae). AlI taxa involved, and their geografical distribution, are described, discussed, and illustrated. The material examined is listed, and a dichotomus key for the identification of the Brazilian species of Aspilia, is presented. About 1200 exsiccatae, from 22 Brazilian and 16 foreign herbaria, were studied, 61 species are recognized, 19 of which are new to science. The genus is maintained in the tribe Heliantheae. The genus Aspilia can be distinguished from other genera of Heliantheae in having ligulate and neuter radial flowers with two or three conspicuous veins, and central achenium slightly compressed, with a scar at its base, from the carpophore. The genus, with about 155 recognise species, occurs in Afr ica, Madagascar, and Tropical. America from Mexico to Argentina. In Brazil, most species are found in "ambientes rupestres", in "cerrados", in gallery forests, and in "restinga", mainly in the states of Minas Gerais, Goiás, Bahia, Mato Grosso, and Mato Grosso do Sul / Expõe-se neste trabalho um estudo taxonômico das espécies brasileiras do gênero Aspilia Th. (Compositae-Heliantheae). Os taxa, com suas respectivas distribuições geográficas, são descritos, discutidos e ilustrados.Elaborou-se relação de material examinado e uma chave dicotômica com a finalidade de identificar as espécies brasileiras, muitas das quais apresentam grande afinidade entre si. Com base no estudo de cerca de 1.200 exsicatas, provenientes de 22 herbários nacionais e 16 herbários do exterior, 61 espécies são reconhecidas, das quais 19 são novas. O gênero é mantido na tribo Heliantheae s.l., subtribo Ecliptinae. O gênero Aspilia, além de outras características de menor expressão, pode ser distinguido de outros da tribo por apresentar flores do raio liguladas e neutras, com duas a três nervuras conspícuas e aquênio do disco, levemente comprimido, com cicatriz na base. O gênero com cerca de 155 nomes é encontrado na África, Madagascar e no continenete americano desde o México até à Argentina. - No Brasil, a maioria das espécies se encontra em ambiente rupestre, cerrado, mata de galeria e restinga, principalmente nos Estados de Minas Gerais, Goiás, Bahia, Mato Grosso e Mato Grosso do Sul

Thesis (M.Sc. (Crop science)) --University of Limpopo, 2007 / Vernonia (Vernonia galamensis) is a new potential industrial oilseed crop. The seeds of this crop contain unusual naturally epoxidised fatty acids which are used in the production of various industrial products. The objective of this study was to evaluate the genetic diversity of selected vernonia lines in Limpopo Province through morphological, seed oil content and RAPD DNA markers. Significant differences were observed for days to 50 % flowering (93 - 140 days), plant height (141.80 - 166.33 cm), number of productive primary heads (29 - 60 head/plant), number of productive secondary heads (12 - 30 head/plant), thousand seed weight (1.85 - 3.52 g) and seed yield (454.44 - 786.85 kg/ha) between lines. Further results from oil analysis showed differences in the contents of seed oil (22.4 - 29.05%), vernolic acid (73.09 - 76.83%), linoleic acid (13.02 - 14.05%), oleic acid (3.77 - 5.28%), palmitic acid (2.48 - 2.98%) and stearic acid (2.26 - 2.75%). Among 13 RAPD DNA primers screened, primer OPA10 amplified DNA samples and resulted in four distinct groupings among tested lines. Four promising lines were selected viz. Vge-16, Vge-20, Vge-27 and Vge-32 displaying greater seed yield, increased vernolic acid content and reduced number of days to 50 % flowering. / National Research Foundataion

No description available.

Members of the genus Packera (Asteraceae) are widespread in North America, but most are found in western regions of the continent where extensive morphological integradation is common. Previous molecular systematic studies found that four species in southwestern Alberta, a region proposed to be at the interface of the Cordilleran and Laurentide ice sheets during the last advance of Pleistocene glaciation, showed unusually high levels of inter- and intrapopulational chloroplast DNA variation. The present study analyzed chloroplast haplotype phylogeny, frequency variation, and geographic distribution patterns in Packera contermina and closely related species P. pseudaurea, P. cana, and P. cymbalarioides from southwestern Alberta, nothern Montana, and northwestern Wyoming. Restriction site analyses of chloroplast DNA from 730 individuals across 34 populations of the four species revealed fifteen haplotypes, of which seven are commonly found in other North American Packera species. Three haplotypes were detected in P. cymbalarioides, seven in P. cana, eight in P. pseudaura, and twelve in P. contermina. The level of ahplotype frequency variation among populations was high in P. cymbalarioides (0=I) moderate to low in P. contermina (0=0.333) and P.cana (0=0.261), and very low in P.pseudaurea (0=0.085), possibly reflecting differences in the species' history. Phylogenetic analyses revealed 2 groups of haplotypes, one of which is found mainly in populations from the Great Basin of North America and the second in populations of more coastal and northern regions. The presence of haplotypes from both groups of Packera species suggests that the cpDNA diversity in southern Alberta arisen through hybridization/introgression events that have involved a number of species from outside of the region. / x, 81 leaves : ill., maps ; 28 cm.

Since their discovery, transposable elements (TEs) have been regarded either as useful building blocks of genomes, or as "selfish DNA": genetic parasites that exploit the sexual cycle to spread in copy number within populations to the detriment of their hosts. If the "selfish DNA" hypothesis is correct, TEs are expected to deteriorate and be lost from asexual populations. This thesis tests the predictions of the "selfish DNA" hypothesis in four asexual plant species, focusing on patterns of nucleotide diversity and nucleotide substitution. Sequences bearing strong resemblance to known TE families including Ty1/copia, Ty3/gypsy, and LINE-like elements were successfully isolated from all four plant species, and showed patterns of nucleotide substitution consistent with a long history of purifying selection. Stochastic simulations were also conducted, and suggested that this result is expected if the host species has been asexual for less than tens of thousands of generations.

When imbibed at their optimum germination temperature of 25°C, achenes of Tagetes minuta L. germinate over a period of approximately 48 h. At temperatures of between 35°C and 39°C, the achenes do not germinate but enter into a state of thermoinhibition. These supra-optimal conditions do not harm the achenes, however, and when the temperature is reduced below 35°C radicle emergence may be observed within 4 h. Achenes which have been thermoinhibited for periods of 24 h or more show "accelerated germination" which takes only 24 h, although the actual germination curve is identical to that of normally germinated achenes. This suggests that the achenes are metabolically active at thermoinhibitory temperatures and undergo most of the processes of normal germination, but that at some point any further development is halted, preventing radicle emergence. When the temperature is reduced, this block on germination is removed and since the achenes are already primed for germination, this occurs within a short time. An analysis of the proteins produced by germinating and thermoinhibited achenes was conducted using SDS-polyacrylamide gel electrophoresis (SDS-PAGE). This procedure was able to resolve approximately 40 different protein bands, but no differences were observed between thermoinhibited and germinating achenes. Two dimensional polyacrylamide gel electrophoresis (20-PAGE) was able to resolve approximately 200 individual polypeptides. The vast majority of polypeptides in T. minuta achenes are acidic, although the number of neutral to basic polypeptides increases as germination progresses. Ten polypeptides were identified which were specific to thermoinhibited achenes. These formed two distinct groups on the twodimensional gels. The larger group contained seven proteins, ranging in size from 22 kDa to 26.7 kDa and with isoelectric points of between 3.0 and 4.0. The smaller group contained three polypeptides with molecular weights of about 14 kDA and a pi of approximately 3.0. These polypeptides were all extremely specific to thermoinhibited achenes and declined rapidly when the incubation temperature was reduced, in a manner which correlated with an increase in the germinability of the achenes. Several characteristics of the expression of these polypeptides were similar to characteristics of embryo-dormancy in seeds where dormancy is thought to be actively imposed by the expression of specific dormancy-associated genes. This, along with the very tightly-regulated nature of these 10 polypeptides, suggests that thermoinhibition in T. minuta may be regulated through gene expression and that these ten polypeptides may represent the products of genes responsible for preventing radicle emergence at unfavourable temperatures. Since these polypeptides were only resolved using silver-staining and could not therefore be used for amino acid sequence analysis, this hypothesis was further investigated using differential display of mRNA to isolate genes which are expressed specifically in thermoinhibited achenes. A large number of cDNA fragments which were specific to either germinating or thermoinhibited achenes were identified and extracted from the differential display gels. Those cDNAs specific to the thermoinhibited achenes were taken for further analysis. Of the 62 fragments excised from the gels, 25 could be reamplified to generate single bands of the correct size on agarose gels. A further 22 cDNAs produced multiple bands, where one band was much brighter than the others and correlated with the size of the original fragment. Thirteen of the cDNAs which' generated single bands were cloned into the plasmid vector pGEM®-T Easy and transformed into either Escherichia coli JM109 or E. coli XL1-Blue. Recombinant colonies were identified using blue-white colour selection and the presence of the insert confirmed by colony blotting and restriction analysis. Three clones were chosen for each of the cDNAs. Reverse northern analysis confirmed that all 39 clones were specific to the mRNA pool of thermoinhibited achenes. High quality sequence data were obtained for 27 of the cDNA samples, the remainder appeared to have been degraded in transit. Alignment of the various sequences revealed that a total of 14 different sequences had been cloned, indicating that several of the bands isolated from the differential display gels contained multiple sequences. Electronic homology searches tentatively identified three of the sequences, whilst the remainder did not show significant homology to any known sequences. Of the cDNAs identified in this way, one may encode a plant transcription factor-like or nuclear RNA-binding protein whilst the other two may encode an RNase-L Inhibitor-like protein and a miraculin homologue. The potential roles of such genes in the imposition or maintenance of the thermoinhibited state are discussed. Although further research needs to be conducted to isolate full length cDNA sequences and to determine their exact expression patterns in germinating and thermoinhibited achenes, these results are consistent with the hypothesis that thermoinhibition in T. minuta achenes is under positive genetic control in a manner analogous to embryo dormancy. This thesis represents the first molecular study of thermoinhibition as well as the first report of active control over this phenomenon in any species. Since thermoinhibition, unlike dormancy, can be rapidly imposed and released under strictly controlled conditions without the need for any dormancy breaking treatment, T. minuta achenes represent an excellent model system for studies on the molecular control of seed germination. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.

Craspedia (Compositae: Gnaphalieae) is a genus of 23 species found only in Australia and New Zealand. New Zealand species of Craspedia have confusing and continuous character variation, with boundaries between species often indistinct and relationships difficult to elucidate. Taxonomic treatments in the genus so far have been regionally based, with the result that species between New Zealand and Australia have not been adequately compared. Phylogenetic analyses of ITS, ETS and psbA-trnH non-coding spacers show that New Zealand Craspedia is a monophyletic group nested within Australian Craspedia. This is consistent with a jump-dispersal event from Australia to New Zealand across the Tasman Sea. The New Zealand lineage is identified as sister to one of two Australian lineages, which consists of mainly subalpine and alpine species found on the main divide of south eastern Australia and in Tasmania. An estimate of when New Zealand Craspedia diverged, using ITS substitution rates from other mainland/island disjunctions in Compositae, gave an approximate date of between 650,000 and 325,000 years ago. This is consistent with the New Zealand fossil pollen record, and with other molecular studies, in suggesting that the Pleistocene, a period of mountain building and climate change, has been an important factor in the evolution of the New Zealand herbaceous flora. The two Australian lineages have not previously been recognised based on morphology and it is suggested they represent two independent species radiations into the Australian alpine zone. Although the New Zealand clade is only partly resolved, the phylogenetic analyses of ITS and ETS indicate that some relationships are incongruent with those previously suggested by morphology and current species boundaries.

Thesis (Ph.D. (Botany)) - Rhodes University, 2007.

A presente tese tenta demonstrar a validade do uso de lactonas sesquiterpênicas como marcadores sistemáticos em angiospermas, principalmente dentro da família Asteraceae, onde se encontram quase todas as substâncias isoladas até o momento. O trabalho teve como etapa inicial o levantamento de dados sobre ocorrência de lactonas sesquiterpênicas em plantas, e a sistematização desdes dados de acordo com a classificação vegetal das espécies portadoras destas substâncias. Na tentativa de estabelecer os prováveis caminhos evolutivos destas micromoléculas, e usá-las como marcadores sistemáticos, utilizam-se dois parâmetros químicos designados O e E. O primeiro consiste em um índice de oxidação médio por átomo de carbono das substâncias. O segundo consiste em um grau de especialização dos esqueletos, dado ou pelos seus números de ordem nas colunas do esquema biogenético, ou pelo seu número médio de transformações (ligamento ou desligamento de ligações carbono-carbono) sofridos por cada átomo de carbono do esqueleto em comparação com um precursor. As médias dos valores de O e E de lactonas sesquiterpênicas de um taxon produzem seus respectivos AEo e AEe , ou seja seus índices de avanço evolutivo em relação a oxidação e à especialização destas substâncias. Estes foram comparados (a nível de família) com índices de evolução morfológicasegundo Sporne (IS) obtendo bons resultados. Com base na metodologia indicada traçou-se para o grupo das lactonas sesquiterpênicas um caminho evolutivo provável que ajuda a entender as relações filéticas entre Apiaceae e Asteraceae. Dentro de Asteraceae, lactonas sesquiterpênicas mostram-se úteis para confirmar os trabalhos mais recentes da subdivisão da família em subfamílias e tribos. Dentro da tribo Heliantheae a análise de dados citogenéticos, aliados aos valores de AEo e AEe , mostra claramente tendências paralelas dos números de cromossomos das subtribos, comparados com a diversificação estrutural e o nível de oxidação de suas substâncias. Finalmente o valor dos índices AEo e AEe em classificação vegetal foi posto a prova tentando classificar, dentro das tribos de Asteraceae, espécies recentemente estudadas, obtendo-se excelentes resultados. / The present thesis attempts to demonstrate the validity of the use of sesquiterpene lactones as systematic markers in angiosperms, chiefly in the family Asteraceae where nearly all presently known compounds are located. Initially all published data on the occurrence of sesquiterpene lactones in plants are listed. followed by the systematization of the data with respect to the classification of the sesquiterpene lactone containing species. In the attempt to establish the probable evolutionary pathways of these micromolecules and to use them as systematic markers, two chemical parameters. designated O and S, were used. The former consists in a mean oxidation index per carbon atom of the compounds. The latter consists in a specialization index for skeletons, given by the symbols which define their position on the columns of the biogenetic scheme, or by the mean number of transformations (formation or breakage of carbon-carbon bonds) suffered by each carbon atom of a skeleton in comparason with a precursor. The means of the O and E values of sesquiterpene lactones of a taxon give the respective EAo and EAe values, i. e. their evolutionary advancement in relation to the oxidation state and the skeletal specialization of these compounds. The EA values were compared (at the family leveI) with Sporne indices (SI) based on morphological criteria. Based on the indicated methodology a probable pathway for the biogenetic group of sesquiterpene lactones was developed. This aids in the understanding of phyletic relations between Apiaceae and Asteraceae. Within the Asteraceae sesquiterpene lactone data are consistent with recent subdivisions of the family in subfamilies and tribes. Within the tribe Heliantheae the analysis of cytagenetic data, compared with EAo and EAe values, shows clearly parallel trends in the number of the chromosomes of the subtribes, as compared with the oxidation state and the skeletal specialization of their sesquiterpene lactones. Finally the value of the EAo and EAe indices in plant classification was evaluated achieving the placement, within the Asteraceae tribes, of recently studied species with satisfactory results.

A variação sazonal na produção de compostos secundários em Tithonia diversifolia (Hemsl) Gray foi investigada desde a primavera de 2002 até o inverno de 2003. Coletas bimensais foram realizadas com posterior extração e fracionamento do material vegetal (folhas e flores). As amostras foram monitoradas por CCD e analisadas quanto a atividade antimicrobiana contra Staphylococcus aureus, Escherichia coli, Salmonella choterasuis e Pseudomonas aeruginosa, pelo método de microplaca. Os perfis cromatográficos foral distintos para as diferentes épocas do ano, sendo evidenciada a presença de um grupo de substâncias em maior quantidade no mês de Abril de 2003 (outono), período de pré-florada desta espécie. Os extratos foram ativos para apenas dois microrganismos dentre os quatro testados. Algumas frações apresentaram CIM (concentração inibitória mínima) significativa (<1mg/mL). / The seasonal variation upon production of active compounds in Tithonia diversifolia (Hemsl) Gray was investigated from spring of 2002 until winter of 2003. Leaf samples were collected every three months for posterior extraction and analysis . The samples were monitored by Thin Layer Chromatography (TLC) and analyzed for anti-microbial activities on Staphylococcus aureus, Escherichia coli, Salmonella choterasuis and Pseudomonas aeruginosa, using micro-plate method. The TLC results showed a clear accumulation of active compounds during April . The extracts were active for only two microorganisms of a total of four studied.