Title from PDF of title page (University of Missouri--Columbia, viewed on February 24, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Gary Stacey. Vita. Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 95-100). Also available in electronic version.

Thesis (Ph. D.)--Groningen, 1983. / Description based on print version record. Includes bibliographical references (p. 123-132).

Made available in DSpace on 2014-06-11T19:26:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-10-01Bitstream added on 2014-06-13T19:54:08Z : No. of bitstreams: 1 tavares_ag_me_botib.pdf: 1952903 bytes, checksum: b683758c447a987faa46eedb5d509b32 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A cafeína é um alcalóide do grupo das metilxantinas. Em café, sua síntese depende da ação de três enzimas: Metilxanthosina sintase (MS), Teobromina sintase (TS) e Cafeina sintase (CS). A crença de que o consumo de cafeína pode trazer problemas à saúde como também a sensibilidade aos efeitos da cafeína, em alguns consumidores, determinou um crescimento do mercado dos cafés descafeinados em pelo menos 10%. O processo de descafeinização hoje é baseado no uso de solventes, que acarreta em significante perda de compostos essenciais ao sabor e qualidade de bebida. Recentemente, foram descobertas três plantas de Coffea arabica naturalmente descafeinadas no banco de germoplasma do Instituto Agronômico de Campinas (IAC). Estas plantas foram nomeadas AC. Análises bioquímicas nas folhas de AC1 mostraram que esta planta acumula teobromina, percussor da cafeína, não sendo detectada atividade da cafeína sintase. Maluf em 2009 descreveu, a existência de transcritos extras em todas as fases de desenvolvimento de frutos de AC1. Estes transcritos também estão presentes nos estágios verde-cana e cereja de frutos do cultivar mundo novo. Esses resultados obtidos sugerem que o transcrito extra está relacionado ao mecanismo de não produção de cafeína em frutos maduros. Tais resultados representam a possibilidade do desenvolvimento de um cultivar naturalmente descafeinado, e estratégias de melhoramento vêm sendo utilizadas para a transferência desta característica para outros cultivares. O presente trabalho caracterizou as plantas com baixos teores de cafeína através de análises genéticas e moleculares. Através da analise da regulação da expressão do gene caffeine sinthase (CCS), em folhas de café com teores normais e baixos de cafeína. As quantificação dos níveis de expressão, analisados via PCR quantitativo em tempo real revelaram baixa expressão do gene em folhas... / Caffeine is an alkaloid from the methilxanthine group. In coffee the synthesis of caffeine is carried out by three enzymes, methylxanthosine synthase (MS), theobromine synthase (TS) and caffeine synthase (CS). Due to the belief that the caffeine could cause health problems and also to consumers sensitivity to caffeine, the consumption of decaffeinated coffee increased in about 10%. The decaffeination process is based on the use of solvents, this process results in a loss of essentials compounds of flavor and cup quality. Recently, three coffee plants with extremely low levels of caffeine were identified in the IAC Coffea Germoplasm Collection, among non-cultivated C. arabica accessions. They are named AC´s. Bioquimistry assays in AC1 leaves show teobromine accumulation, caffeine precursor, no activity of caffeine synthase was detected. Maluf in 2009 described the existence of extra transcript in all development of AC1 fruit. Those transcripts are also present on latter development stages, yellowish-green and cherry. The Author suggest that this extra transcript is related to non-synthesis of caffeine in mature fruits of cultivar MN and during the development of AC1 fruits. These results represent the possibility of the development of low-caffeine cultivars and coffee breeding programs are been used due to transfer this characteristic to others cultivars. In this work, the naturally caffeine free plants have been caracterizated by molecular and genetics assays. Throught the characterization of the regulation of caffeine synthase gene expression. The quantification of expression by qRT PCR show low expression in leaves of ACs plants comparing the expression of MN and ET4, same cultivar of AC. Expression assays show that abramulosa mutant has low expression comparing to MN cultivar but seperflorens mutant showed a normal expression... (Complete abstract click electronic access below)

Chrysanthem Oides is a common Southern African shrub that grows in a variety of habitats. From coastal shrubland and fynbos to mountainous areas as far north as Kenya. The genus has two species and 8 subspecies. The diagnoses and delimitation of which have been based almost exclusively on morphological characteristics. This project aims to investigate, with the use of phylogenetic species concepts. The validity of these subspecies. Unlike biological species concepts that rely on reproductive isolation as a defining character of a species. Phylogenetic species concepts (PSC) are concerned with delimiting evolutionary significant units (ESUs). ESUs are evolutionarily isolated lineages, and under the PSC a species is an aggregation of organisms consistently diagnosable by a fixed character or combination of characters. This project therefore searched for genetic and physiological characters by which to delimit ESUs within the Cill), samhemoides genus. DNA sequencing was used to investigate the genetic characters, while gas exchange studies were used to investigate the ecophysiological characters. DNA sequence analysis indicated that the ESUs can be diagnosed by genetic means and that one species may be of hybrid origin. Field studies of three disparate genetically identifiable ESUs from three disparate climates found that there are noticeable differences in ecophysiological responses of these ESUs in the field. Plants from each ESU were transferred to a greenhouse and grown under identical conditions for several months and compared to determine if these traits are inherent, or elastic in relation to environmental conditions. Under simulated high rainfall conditions. There does not appear to be a significant difference in the photosynthetic traits.

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