A citricultura brasileira destaca-se como a de maior expressão em nível mundial, com cerca de 27,9% da produção mundial de laranjas e 59% da produção global de suco concentrado congelado de laranja. No entanto, apresenta uma vulnerabilidade que é o predomínio de uma única espécie de porta-enxerto, o limão \'Cravo\', com aproximadamente 85% das plantas cítricas plantadas sobre ele. Assim, uma maior diversificação dos porta-enxertos é necessária mas isto depende também da obtenção e da disponibilização de variedades superiores ao limão Cravo. O porta-enxerto é de fundamental importância na formação da muda cítrica, visto que ele interfere em vários aspectos da planta enxertada, dentre eles o vigor da copa e o tamanho das plantas. Atualmente, devido ao surgimento de novas doenças e a necessidade de maximização dos recursos alocados na propriedade citrícola, tem sido utilizado o plantio de pomares mais adensados, com consequentemente aumento no interesse da produção de plantas com menor porte. Uma das possibilidades de se obter plantas de porte baixo é por meio do uso de portaenxertos ananicantes ou semi-ananicantes, sendo que alguns autores já verificaram que plantas autotetraplóides, quando usadas como porta-enxertos, induzem à formação de plantas de porte baixo. O objetivo inicial deste trabalho foi obter e identificar plantas autopoliplóides de limão Cravo, tangerinas Cleópatra e Sunki, utilizando-se o método de cultivo in vitro de segmentos de epicótilo temporariamente em meio de cultura contendo colchicina, seguido de regeneração das brotações em meio sem o alcalóide. A colchicina causou toxidez aos explantes, nos diversos tempos de cultivo e concentrações testadas. Várias plantas foram obtidas e dentre estas, 27 foram selecionadas por possuir características morfológicas semelhantes à plantas poliplóides. A seguir, foram realizados experimentos com seis plantas selecionadas (duas de cada espécie) visando confirmar a ploidia e a origem nucelar, além de caracterizar a morfologia das folhas, a densidade estomática e alguns parâmetros fisiológicos. Dentre as seis plantas, apenas quatro foram confirmadas como sendo autotetraplóides pelo método de citometria de fluxo. Estas, geralmente apresentaram folhas com comprimento significativamente menor, maior espessura do limbo foliar e menor densidade estomática nas folhas. Todas as seis plantas apresentaram alguma modificação em parâmetros fisiológicos, mas ainda não se pode determinar se estas modificações poderão afetar as taxas de crescimento. / The Brazilian citriculture stands out as the greatest expression worldwide, with about 27.9% of world production of oranges and 59% of global production of frozen orange juice concentrate. However, it presents a vulnerability that is the predominance of a single species of rootstock, the \'Cravo\' lemon, with approximately 85% of citrus planted on it. Thus, greater diversification of rootstocks is necessary, which also depends on obtaining and provision of superior kind of lemon Cravo. The rootstock is of fundamental importance in shaping the citrus scion, since it interferes with various aspects of graft, such as the vigour of the graft and plant size. Currently, due the appearance of new diseases and the need to maximize resources allocated in the citrus farm, more dense citrus orchards have been used, increasing the interest in the production of smaller plants. One of the possibilities of obtaining plants of small size is through the use of dwarf or semi-dwarf rootstocks, and some authors have found that plants autotetraploids, when used as rootstock, induce the formation of small-sized plants. The initial objective of this study was to obtain and identify plants autopoliploids of \'Cravo\' lemon, \'Cleopatra\' and \'Sunki\' tangerines, using the method of in vitro culture of segments of epicotyl temporarily in the culture medium containing colchicine, followed by shoots regeneration in medium without the alkaloid. The colchicine caused toxicity in explants, at the different times of cultivation and concentrations tested. Several plants were obtained and among these, 27 were selected for morphological characteristics similar to polyploid plants. Afterwards, trials were conducted with six selected plants (two of each kind) to confirm the nucelar ploidy origin, and to characterize the morphology of the leaves, stomatal density and some physiological parameters. Among the six plants, only four were confirmed as autotetraploids by method of flow cytometry. These, generally presented leaves with small length, greater thickness of the leaf lamina and lower stomatal density in leaves. All six plants showed some change in physiological parameters, but data could not determine whether these changes could affect the plants growth rates

A poliploidia teve importante papel no melhoramento de muitas espécies de plantas, principalmente nos cereais, incluindo híbridos intergenéricos. O processo de poliploidização, geralmente, produz novos e desejáveis fenótipos ou fornece suporte para cruzamentos de plantas em programas de melhoramento. Esse trabalho apresenta o resultado da indução de poliploidia em duas cultivares de mandioca (\'Porquinho\' e \'Vassourinha\') que foram tratadas com diferentes concentrações de colchicina (0,05%, 0,10% e 0,15%), em meio de cultura, durante 48 e 96 horas. As plantas regeneradas foram analisadas citologicamente por citometria de fluxo e pela contagem do número de cromossomos. Adicionalmente, análises do tamanho e da frequência dos estômatos foram realizadas e o resultado comprovou que podem ser utilizadas como screening das plantas tratadas. O tratamento com 0,1% de colchicina, em meio de cultura, durante 96 horas apresentou maior número de plantas tetraplóides produzidas sobre o número de plantas regeneradas nas duas cultivares avaliadas. Não há diferenças entre as doses de colchicina e tempos de exposição a droga no número de tetraplóides encontrados em cada tratamento. Entretanto, foi possível verificar que existe diferença significativa na produção de tetraplóides entre as cultivares analisadas, indicando que pode haver uma resposta genética à indução da duplicação dos cromossomos com colchicina. / The polyploidy played an important role in the improvement of many species of plants, especially in cereals including intergeneric hybrids. The process of polyploidy usually produces new and desirable phenotypes or provides support for crosses of plants in breeding programs. This research work reports the result of polyploidy induction in two cassava cultivars (\'Porquinho\' and \'Vassourinha\') by different colchicine concentrations (0.05 %, 0.10 % and 0.15 %) in culture medium exposed for 48 or 96 hours. Regenerated plants were examined cytologically by flow cytometry and chromosome counting. Additionally, analysis of the size and frequency of stomata were performed and the results showed that can be used for screening of the treated plants. Treatment with 0.1% colchicine in the culture medium for 96 hours showed a higher number of tetraploid plants produced about the number of regenerated plants in both cultivars evaluated. No significant differences among colchicine doses and duration times treatment were found in the number of tetraploids found in each treatment. However, we observed a significant difference in tetraploid production between the cultivars analyzed, indicating that there may be a genetic response to induction of chromosome doubling with colchicine.

A poliploidia teve importante papel no melhoramento de muitas espécies de plantas, principalmente nos cereais, incluindo híbridos intergenéricos. O processo de poliploidização, geralmente, produz novos e desejáveis fenótipos ou fornece suporte para cruzamentos de plantas em programas de melhoramento. Esse trabalho apresenta o resultado da indução de poliploidia em duas cultivares de mandioca (\'Porquinho\' e \'Vassourinha\') que foram tratadas com diferentes concentrações de colchicina (0,05%, 0,10% e 0,15%), em meio de cultura, durante 48 e 96 horas. As plantas regeneradas foram analisadas citologicamente por citometria de fluxo e pela contagem do número de cromossomos. Adicionalmente, análises do tamanho e da frequência dos estômatos foram realizadas e o resultado comprovou que podem ser utilizadas como screening das plantas tratadas. O tratamento com 0,1% de colchicina, em meio de cultura, durante 96 horas apresentou maior número de plantas tetraplóides produzidas sobre o número de plantas regeneradas nas duas cultivares avaliadas. Não há diferenças entre as doses de colchicina e tempos de exposição a droga no número de tetraplóides encontrados em cada tratamento. Entretanto, foi possível verificar que existe diferença significativa na produção de tetraplóides entre as cultivares analisadas, indicando que pode haver uma resposta genética à indução da duplicação dos cromossomos com colchicina. / The polyploidy played an important role in the improvement of many species of plants, especially in cereals including intergeneric hybrids. The process of polyploidy usually produces new and desirable phenotypes or provides support for crosses of plants in breeding programs. This research work reports the result of polyploidy induction in two cassava cultivars (\'Porquinho\' and \'Vassourinha\') by different colchicine concentrations (0.05 %, 0.10 % and 0.15 %) in culture medium exposed for 48 or 96 hours. Regenerated plants were examined cytologically by flow cytometry and chromosome counting. Additionally, analysis of the size and frequency of stomata were performed and the results showed that can be used for screening of the treated plants. Treatment with 0.1% colchicine in the culture medium for 96 hours showed a higher number of tetraploid plants produced about the number of regenerated plants in both cultivars evaluated. No significant differences among colchicine doses and duration times treatment were found in the number of tetraploids found in each treatment. However, we observed a significant difference in tetraploid production between the cultivars analyzed, indicating that there may be a genetic response to induction of chromosome doubling with colchicine.

Cette thèse met en évidence, à travers deux exemples, les potentialités de la chimie radicalaire des xanthates pour la réalisation de réactions radicalaires réputées difficiles. Après une brève introduction sur la chimie radicalaire par propagation de chaîne puis plus particulièrement sur la chimie radicalaire des xanthates, une nouvelle méthodologie de synthèse de composés spirocycliques, et notamment de gamma-spirolactones, est présentée. Elle s'appuie sur une réaction de spirocyclisation déaromatisante sur un noyau furanique et peut être étendue à la synthèse de spirolactames en remplaçant le furane par un pyrrole. Dans un second temps, une nouvelle approche de synthèse d'analogues de la Colchicine, molécule issue du colchique Colchicum autumnale connue pour ses propriétés antitumorales, est proposée. Elle repose sur la formation du cycle B à 7 chaînons de cette molécule par voie radicalaire en 2 ou 3 étapes et permet l'accès rapide à des analogues variés.

A large sector of the forestry industry of South Africa comprises Eucalyptus species, covering approximately 49% of the forestry plantation area. Polyploidy induction has become an attractive tool to increase yield and reduce invasiveness in forestry species. Polyploidy induction in Eucalyptus using colchicine treatments on seed and axillary buds was undertaken to produce tetraploids that could be used in breeding programmes; specifically to increase yield and decrease species invasiveness through the production of triploids after crossing with diploid parents. Eight seedlots of E. urophylla and seven of E. grandis were treated with four colchicine concentrations (0.00, 0.01, 0.03, 0.05%) at two exposure times (18 h and 24 h), treating two seeds per treatment, repeated eight times. For axillary bud induction, 20 buds of two E. grandis clones and three E. grandis × E. urophylla hybrids and one E. grandis × E. nitens hybrid were treated with four colchicine concentrations (0.0, 0.5, 1.0, 1.5%) for three consecutive days. A known tetraploid hybrid E. grandis E. camaldulensis and its corresponding diploid were included as reference material. Seedlings and bud sports were pre-screened by determining stomatal guard cell lengths. Seedlings and bud sports displaying cell lengths significantly (p<0.0001) larger than the diploid were selected as putative polyploids. Polyploidy was then confirmed by quantifying the DNA content using flow cytometry. Stomatal frequencies and guard cell chloroplast frequencies were also determined in the induced tetraploid seedlings to evaluate their suitability to discern between ploids. All putative polyploidy seedlings, identified in the pre-screening process, were confirmed, using flow cytometry, as either tetraploids or mixoploids. Of the 17 E. urophylla putative polyploids, from various seedlots, six were tetraploid and 11 mixoploid. In E. grandis one of the five putative polyploids, from various seedlots, was tetraploid and four mixoploid. Pre-screening of bud sports was less accurate; only four of the 12 E. grandis hybrid putative polyploids were mixoploid and only three of the six E. grandis putative polyploids were mixoploid. E. urophylla seedlings were more sensitive to colchicine than E. grandis seedlings displaying a lower survival rate (52%) than E. grandis (63%). Extreme treatments that caused the lowest survival rates were also responsible for most of the polyploidy successful inductions; 0.05%/18 h and 0.05%/24 h for E. urophylla and 0.03%/24 h and 0.05%/24 h for E. grandis. Phenotypic effects of colchicine included shorter, thicker roots and hypocotyls; darker leaves; longer and narrower leaves in some tetraploids; and asymmetrical leaf margins in many mixoploids and tetraploids compared with the controls. In the tetraploids, stomata were significantly larger (p<0.0001) and less frequent (p<0.001). A significant (p<0.001) increase in the number stomatal chloroplasts was also ascertained. Confirmed mixoploid seedlings all displayed tetraploid leaves based on stomatal size and thus classified as periclinal chimeras. In bud sports, only leaves with islands of diploid and tetraploid stomata in the confirmed mixoploids were encountered. Mixoploid bud sports were thus either sectional or mericlinal chimeras. Stomatal size proved to be a suitable pre-screening method, especially in polyploidy induction in seedlings. Additionally confirmed tetraploids exhibited significantly different stomatal frequencies and stomatal chloroplast frequencies compared with the diploids, thus proving to be suitable detection methods for polyploidy screenings. Polyploidy induction in seed was effective, however, less effective in axillary buds which requires further research to refine methods. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Diss. (sammanfattning) Uppsala : Univ., 2004. / Härtill 5 uppsatser.

A citricultura brasileira destaca-se como a de maior expressão em nível mundial, com cerca de 27,9% da produção mundial de laranjas e 59% da produção global de suco concentrado congelado de laranja. No entanto, apresenta uma vulnerabilidade que é o predomínio de uma única espécie de porta-enxerto, o limão \'Cravo\', com aproximadamente 85% das plantas cítricas plantadas sobre ele. Assim, uma maior diversificação dos porta-enxertos é necessária mas isto depende também da obtenção e da disponibilização de variedades superiores ao limão Cravo. O porta-enxerto é de fundamental importância na formação da muda cítrica, visto que ele interfere em vários aspectos da planta enxertada, dentre eles o vigor da copa e o tamanho das plantas. Atualmente, devido ao surgimento de novas doenças e a necessidade de maximização dos recursos alocados na propriedade citrícola, tem sido utilizado o plantio de pomares mais adensados, com consequentemente aumento no interesse da produção de plantas com menor porte. Uma das possibilidades de se obter plantas de porte baixo é por meio do uso de portaenxertos ananicantes ou semi-ananicantes, sendo que alguns autores já verificaram que plantas autotetraplóides, quando usadas como porta-enxertos, induzem à formação de plantas de porte baixo. O objetivo inicial deste trabalho foi obter e identificar plantas autopoliplóides de limão Cravo, tangerinas Cleópatra e Sunki, utilizando-se o método de cultivo in vitro de segmentos de epicótilo temporariamente em meio de cultura contendo colchicina, seguido de regeneração das brotações em meio sem o alcalóide. A colchicina causou toxidez aos explantes, nos diversos tempos de cultivo e concentrações testadas. Várias plantas foram obtidas e dentre estas, 27 foram selecionadas por possuir características morfológicas semelhantes à plantas poliplóides. A seguir, foram realizados experimentos com seis plantas selecionadas (duas de cada espécie) visando confirmar a ploidia e a origem nucelar, além de caracterizar a morfologia das folhas, a densidade estomática e alguns parâmetros fisiológicos. Dentre as seis plantas, apenas quatro foram confirmadas como sendo autotetraplóides pelo método de citometria de fluxo. Estas, geralmente apresentaram folhas com comprimento significativamente menor, maior espessura do limbo foliar e menor densidade estomática nas folhas. Todas as seis plantas apresentaram alguma modificação em parâmetros fisiológicos, mas ainda não se pode determinar se estas modificações poderão afetar as taxas de crescimento. / The Brazilian citriculture stands out as the greatest expression worldwide, with about 27.9% of world production of oranges and 59% of global production of frozen orange juice concentrate. However, it presents a vulnerability that is the predominance of a single species of rootstock, the \'Cravo\' lemon, with approximately 85% of citrus planted on it. Thus, greater diversification of rootstocks is necessary, which also depends on obtaining and provision of superior kind of lemon Cravo. The rootstock is of fundamental importance in shaping the citrus scion, since it interferes with various aspects of graft, such as the vigour of the graft and plant size. Currently, due the appearance of new diseases and the need to maximize resources allocated in the citrus farm, more dense citrus orchards have been used, increasing the interest in the production of smaller plants. One of the possibilities of obtaining plants of small size is through the use of dwarf or semi-dwarf rootstocks, and some authors have found that plants autotetraploids, when used as rootstock, induce the formation of small-sized plants. The initial objective of this study was to obtain and identify plants autopoliploids of \'Cravo\' lemon, \'Cleopatra\' and \'Sunki\' tangerines, using the method of in vitro culture of segments of epicotyl temporarily in the culture medium containing colchicine, followed by shoots regeneration in medium without the alkaloid. The colchicine caused toxicity in explants, at the different times of cultivation and concentrations tested. Several plants were obtained and among these, 27 were selected for morphological characteristics similar to polyploid plants. Afterwards, trials were conducted with six selected plants (two of each kind) to confirm the nucelar ploidy origin, and to characterize the morphology of the leaves, stomatal density and some physiological parameters. Among the six plants, only four were confirmed as autotetraploids by method of flow cytometry. These, generally presented leaves with small length, greater thickness of the leaf lamina and lower stomatal density in leaves. All six plants showed some change in physiological parameters, but data could not determine whether these changes could affect the plants growth rates

Fairway crested wheatgrass, which is identified taxonomically as Agropyron cristatum (L . ) Gaertn. (45 ), A. cristatiforme (38) , or A. pectiniforme Roem. and Schult (22), is an economically important range grass belonging to the "crested wheatgrass complex" (24, 38). The crested wheatgrass complex includes diploid, 2n = 14, tetraploid, 2n = 28, and hexaploid, 2n = 42, forms (1, 11, 22). The variety Fairway and Fairway-like derivatives are the only known diploid members of the species complex (24, 38). Meiotic chromosome behavior of Fairway diploids appears to be typical of other diploid species; however, the number of plants examined cytologically has been relatively small. Although Fairway crested wheatgrass is a good seed producer, interplant variation in fertility is high (13, 22, 25, 42). Irregular chromosome behavior is a common source of sterility and may be contributing to the variable seed set in diploid crested wheatgrass. No information is available concerning the relation of meiotic chromosome behavior to fertility in Fairway crested wheatgrass. Polyploid crested wheatgrasses are generally considered to be of autoploid origin, i.e., they are derived by duplication of the chromosome complement of a diploid prototype. Chromosome pairing in the polyploid species (31), in interspecific hybrids (12), and in polyhaploid plants (11) substantiate the autoploid derivation of polyploid crested wheatgrass. Diploid and tetraploid forms of crested wheatgrass have been hybridized by Knowles (24), and chromosome pairing in the hybrids suggest a close relation between the diploid and tetraploid genomes. Colchicine-induced tetraploids of Fairway crested wheatgrass have been produced by Knowles, 1 and these artificial tetraploids are currently being utilized in his crested wheatgrass breeding program. If the full breeding and cytogenetic potentials of diploid crested wheatgrass are to be realized, the meiotic chromosome behavior and the cytotaxonomic status of this species must be fully understood. The present investigation was designed to provide further information concerning the cytogenetic characteristics of Fairway crested wheatgrass and its autotetraploid derivatives. This investigation was established with the following objectives: 1. To examine meiotic chromosome behavior of Fairway crested wheatgrass. 2. To determine the relation of meiotic chromosome behavior to fertility in Fairway crested wheatgrass. 3. To evaluate the effectiveness of several colchicine treatments in doubling the chromosome complement of Fairway crested wheatgrass. 4. To determine the effect of induced polyploidy on plant morphology in colchicine-induced tetraploids of Fairway crested wheatgrass. 5. To determine the meiotic chromosome behavior and fertility of induced tetraploids of Fairway crested wheatgrass.

Background Extensively used grasslands are frequently utilised for hay production for equines. Especially, extensive meadows have a great variety of plant species, which may include plants that are poisonous for equines such as meadow saffron (Colchicum autumnale L.). To authors’ knowledge investigations about horses` avoidance behaviour towards dried meadow saffron in hay are missing. Reports of farmers are contrary to clinical symptoms described in case reports and associated with meadow saffron in hay. Objectives The aim of this study was to determine the rejection behaviour of horses for hay contaminated with meadow saffron (MS) when fed ad libitum. Study design An 18-day feeding trial with six adult geldings to observe the rejection behaviour for hay contaminated with MS. Methods The horses were fed a basal diet containing hay ad libitum and a mineral supplement during the feeding trial. At six different daytimes, hay contaminated with 1% or 2% dried MS was provided to the horses over a duration of 1 h. The rejection behaviour was observed personally and by video recordings. If a horse ingested more than two plants of MS during one observation period, the observation was stopped and repeated at another day. When the observation period had to be stopped twice, the horse was excluded from the experiment. Results Five of six horses ingested MS during the first feeding periods. One horse rejected leaves and capsules at the beginning of the study, but it showed repeated ingestion of MS after the seventh observation period. Main limitations Lack of knowledge about secondary plant metabolites affecting taste and their variability between fresh and dried plants. Conclusions The intake of MS in hay by horses could not be ruled out with certainty. Therefore, feeding hay contaminated with MS should be avoided for equids.

Les allocolchicinoïdes constituent une famille de composés présentant un système tricyclique de 6, 7 et 6 carbones respectivement, dont le premier cycle est hautement oxygéné. Plusieurs membres de cette famille possèdent des propriétés biologiques intéressantes. Leurs propriétés anticancéreuses envers une variété de lignées cancéreuses résistantes ont augmenté l'intérêt pour ce type de composé depuis quelques années. Afin d'exploiter des résultats novateurs obtenus récemment dans notre laboratoire, notre groupe de recherche s'est attaqué à la synthèse d'analogues d'allocolchicinoïdes. Celle-ci fait intervenir, comme étapes clés, un couplage de Suzuki menant à des o-aminométhylbiphényles ainsi qu'une cyclisation énantiosélective 7-exo-tet provenant d'une réaction de lithiation-substitution utilisant un complexe chiral BuLi?ligand. Dans ce contexte, une librairie de ligands chiraux a été synthétisée. Les résultats pour l'affinité de ces ligands envers différents métaux ainsi que les résultats préliminaires en synthèse énantiosélective seront présentés dans cette thèse.