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Sunflower (Helianthus annuus) consists of high levels of polyunsaturated fatty acids, making its oil susceptible to oxidation. Tocopherols can retard or prevented oxidation. The aim of this study is to determine the phenotypic tocopherol (vitamin E) composition and genetic diversity of the biosynthetic pathway genes. Seeds were characterized for fatty acid and tocopherol content. A positive correlation was found between oleic acid, γ (r =0.17) and δ (r =0.23) tocopherol but none between linoleic acid and all four tocopherol derivatives. Vitamin E gene homologues were identified and a concomitant pathway constructed, with genes of interest sequenced to determine their genetic variation. A sunflower gene database was developed for these genes and used to obtain 489 SNPs and 145 indels from the accessions evaluated. Only 139 of these SNPs were located in the exon regions of the gene candidates. These exon-based SNPs may influence tocopherol flow through possible enzyme structural modifications / School of Agriculture and Life Sciences / M. Sc. (Life Sciences)

The potential growth-regulating compound 4-chloroglutaranilic acid (CGA) was tested in whole-plant bioassay systems which utilized sunflower seedlings (Helianthus annuus, L.). Test systems included the growth of plants in soil , solid inert (Vermiculite) substrate, and hydroponic (Seed-Pak) pouches.

Orientador: Carlos Roberto Padovani / Banca: Adriano Wagner Ballarin / Banca: José Carlos Martinez / Banca: Jacinta Ludovico Zamboti / Banca: Marie Oshiiwa / Resumo: Este trabalho foi desenvolvido com os objetivos de avaliar a divergência genética de 12 populações de girassol do Banco de Germoplasma da EMBRAPA /Soja de Londrina por meio de técnicas multivariadas; divulgar tópicos recentes e interessantes das técnicas multivariadas que não são explorados nos trabalhos científicos de melhoramento de plantas e orientar a escolha de populações para cruzamentos nos programas de melhoramento genético da cultura de girassol. O modelo experimental constitui-se de delineamento bloco casualizado envolvendo 12 variedades de girassol avaliadas sob cinco caracteres morfoagronômicos. Por meio da análise univariada foi verificada diferença significativa (p<0,05) dos tratamentos para todos caracteres. A aplicação dos componentes principais permitiu a redução bidimensional, com a explicação de 82,5% da variação total. O número de componentes foi avaliado pelo critério de Kaiser e critério Scree-test. A visualização da divergência genética proporcionada pelos escores das duas primeiras variáveis canônicas, evidenciaram grupos geneticamente diferentes. Ambas técnicas apontaram concordância nos resultados. Com base nas estimativas da distância Mahalanobis e distância euclideana foi realizada a análise de agrupamento adotando-se três algoritmos hierárquicos. Para determinar o número de grupos adotou-se o dendrograma, a análise do nível de fusão e a análise do comportamento de similaridade. Para validação utilizou-se o critério de Wilks dentro de cada grupo e gráficos multivariados auxiliaram na interpretação dos resultados. Pode-se concluir pela existência da divergência genética, detectando-se quatro grupos geneticamente diferentes e caracterizado pelos escores médios. / Abstract: The objective of this work was to evaluate genetic divergence in 12 sunflower populations from EMBRAPA/ Londrina Soybean Germplasm Bank, using multivariate techniques, to discuss recent and interesting topics related to the multivariate techniques donþt found in plant improvement scientific papers, and to offer guidelines on how to choose populations for sunflower genetic improvement crossing programs. The experiment included a totally block casualized design, with twelve sunflower varieties, evaluated according to 5 morphoagronomics traits. The univariate analysis showed a significant difference (p<0,05) among treatments for all the traits. Application of main components allowed for a bi-dimensional reduction, with 82,5% of the total variation. The number of components were evaluated by the Kaiser and Scree-test criteria. Genetic divergence visualization provided by the two first canonical variables showed genetically different groups. Both techniques showed the same results. Based on Mahalanobis and Euclidean distance estimates, a clustering analysis was carried out using three hierarchicals algorithms. A dendrogram, a fusion level analysis and a similarity behavior analysis were conducted to determine the number of groups. Validation used the Wilks criteria inside each group, while multivariate graphs helped with data interpretation. Results from this study showed genetic divergence in four groups characterized by average/mean scores. / Doutor

Thesis (M.Dev.) --University of Limpopo, 2007

The suitability of sunflower (Heliantus annuus L.) as a host of Ophraella communa Le Sage (Coleoptera: Chrysomelidae) was evaluated under greenhouse and field conditions. Population dynamics of O. communa on sunflower and on ragweed (Ambrosia artemisiifolia L.) were determined using a life table approach. Sixty percent of O. communa females died during the first 30 days on sunflower while only 14% died on ragweed plants. Only 20% of fertile females laid eggs on sunflower plants as compared with 100% on ragweed plants. Fecundity, life duration, egg viability, and other biological parameters were significantly higher on ragweed plants than on sunflower plants. Ragweed is the main host plant for O. communa. Nevertheless, in specific situations (no-choice) adults and larvae of O. communa can damage sunflower plants. However, O. communa cannot complete its life cycle or increase its population on sunflower plants.

Some mounted ill. / Includes bibliography / x, 120, [268] leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1984

The general aim of this research was to analyse the genetic diversity in Sclerotinia species. More specifically the aims of this research were: to separate the three species of Sclerotinia, S. sclerotiorum (Lib.) de Bary, S. minor Jagger and S. trifoliorum Erikss.; to determine the breeding mechanism in S. minor and S. sclerotiorum; to test S. minor for the possibility of causing head rot of sunflower; to examine isolate of S. sclerotiorum from sunflower for aggressiveness and to see if this correlates with underlying genetic diversity. Sclerotinia species were separated using a variety of morphological and molecular criteria. S. minor, S. sclerotiorum and S. trifoliorum were analyzed on characters including host, sclerotial diameters, ascospore morphism, breeding type and RFLP analysis. Cloned DNA fragments from S. sclerotiorum were used as probes, these were compared with a cloned rDNA probe from Neurospora. These probes enabled clear separation of the Sclerotinia species. Sclerotial diameters appear to be good criteria for separating S. minor from S. sclerotiorum and S. trifoliorum. Host species may be sufficient criteria for separating S. sclerotiorum and S. trifoliorum for the plant pathologist in the field, however it was inadequate to accurately separate all isolates. S. minor and S. sclerotiorum were found to be homothallic ascomycetes. Apothecia were raised from all eight ascospores of a single tetrad from four isolates of S. minor and from an isolate of S. sclerotiorum indicating that inbreeding may be the predominant breeding type mechanism of S. minor. Ascospores from asci of S. minor and S. sclerotiorum were predominantly monomorphic, but rare examples of ascospore dimorphism similar to S. trifoliorum were found. Ascospores of S. minor were shown to be capable of causing head rot of sunflower (Helianthus annuus L.) when inoculated onto the floral face during anthesis. This is the first record of the carpogenic germination of S. minor in Australia and demonstration of infectivity of the ascospores on sunflower. Isolates of S. sclerotiorum differ significantly in aggressiveness on sunflower. One hundred and twenty isolates were collected from head and basal stem rots of sunflower in two locations in south east Queensland. The inoculation of sunflower stems with mycelial plugs and the measurement of lesion development were found to be reliable and revealed differences in lesion lengths produced by the different isolates. The time of assessment after inoculation was found to be of significance. Assessment two days after inoculation was more reliable than after three days or the linear rate of lesion development. The significant differences between isolates indicated that the pathogenicity testing method would also be good for virulence testing. The significant differences between the isolates however, was not consistent with repetition and division of the isolates into groups with different aggressive levels was therefore not possible. Differences in aggressiveness were more indicative of a continuous variation in pathogenicity rather than discrete aggressive groups. The number of significantly different isolates was most associated with the statistical test employed. The different multiple comparison procedures used made more difference in interpretation of aggressiveness than the data itself. Isolate aggressiveness did not correspond to the location of collection. Isolates collected from both head and basal stem rots were capable of causing stem infections therefore no specificity for mode of reproduction or infection was found. S. sclerotiorum attacking sunflower in Queensland and New South Wales was found to belong to one large population. Hierarchical sampling only detected one example of a plant lesion infected by more than one genotype. Thus most diseased plants are the result of a single infection only. Population substructuring could not be detected using 11 single copy Restriction Fragment Length Polymorphism (RFLP) loci, suggesting gene flow occurs within the Australian population. Mycelial Compatibility Groups (MCGs), Random Amplified Polymorphic DNAs (RAPDs) single and multicopy RFLPs analysis indicated differences amongst the genotypes identified by each criteria. From 120 isolates the number of genotypes ranged from 13 to 24 depending on the marker used. However there were many similarities in the assemblages of isolates within each genotype. Genotypic diversity could not be correlated with aggressiveness. Initial mode of infection could not be correlated with genotypic differences. Genotypes were also not specific to geographic locations around Australia. However, genotypes identified in Australia were unique from genotypes identified in Canada and United States. Temporal studies also indicated a single population as genetic uniformity was maintained between years. Frequent recovery of the same genotypes around Australia suggests a clonal population structure. The Australian S. sclerotiorum population attacking sunflower appears to have a large asexual component most likely due to the sclerotial production and homothallic sexual reproduction. Gametic disequilibrium was found for all the populations. However, clonal correction of the samples meant that the majority of populations were not at gametic disequilibrium, indicating random associations among loci. Therefore genetic exchange and recombination would appear to be a component of the reproductive cycle of S. sclerotiorum in Australia.

Thesis (M.A.)--The University of North Carolina at Greensboro, 2008. / Directed by Roy Stine; submitted to the Dept. of Geography. Title from PDF t.p. (viewed Apr. 13, 2010). Includes bibliographical references (p. 58-64).

Thesis (M.S.)--Evergreen State College, 2005. / Includes bibliographical references: p. 77-99.