Thesis (Ph. D.)--University of Wisconsin, 1959. / Typescript. Abstracted in Dissertation abstracts, v. 19 (1959) no. 12, p. 3101. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 302-309).

In this article the term ‘African leafy vegetables’ was adopted to refer to the collective of plant species which are used as leafy vegetables and which are referred to as morogo or imifino by African people in South Africa. Function is central in this indigenous concept, which is subject to spatial and temporal variability in terms of plant species that are included as a result of diversity in ecology, culinary repertoire and change over time. As a result, the concept embraces indigenous, indigenised and recently introduced leafy vegetable species but this article is concerned mainly with the indigenous and indigenised species. In South Africa, the collection of these two types of leafy vegetables from the wild, or from cultivated fields where some of them grow as weeds, has a long history that has been intimately linked to women and their traditional livelihood tasks. Among poor people in remote rural areas the use of these types of leafy vegetables is still common but nationwide there is evidence of decline, particularly in urban areas. Cultivation of indigenous or indigenised leafy vegetables is restricted to a narrow group of primarily indigenised species in South Africa. Seven groups of indigenous or indigenised African leafy vegetables that are important in South Africa were given special attention and their local nomenclature, ecology, use and cultivation are discussed.

Canola (Brassica napus) oil has immense economic value due to its use as food. The production of biodiesel has led to the recent increase in the demand for canola oil, and further reinforced the need to improve the oil content and composition of canola seeds. The content and quality of canola oil is dependent on the process of fatty acid biosynthesis and accumulation of triacylglycerols (TAGs) during seed development. The biochemical pathways leading to the synthesis of fatty acids and TAGs are thoroughly understood, and many of the genes encoding the metabolic enzymes involved in this pathway have been isolated and functionally characterized. Despite comprehensive understanding of fatty acid and TAG biosynthesis, alternate factors and genes involved in the modification of seed oil content and composition are being investigated. This has initiated a new sector of research focusing on a series of transcription factors: LEAFY COTYLEDON1 (LEC1), LEAFY COTYLEDON2 (LEC2), FUSCA3 (FUS3) and WRINKLED1 (WRI1), which play a key role during embryo and seed development. Previous studies in Arabidopsis have demonstrated that the noted transcription factors influence the synthesis and accumulation of oil during seed development. These findings have prompted the design of two studies with the objective of further characterizing the role of these genes. In the first study, a homolog of Arabidopsis LEC1 was isolated from Brassica napus (Bn) microspore derived embryos. BnLEC1 contained the same distinct features identified in LEC1 genes from other plant species. BnLEC1 was inserted into an expression vector, which was subsequently used to transform Arabidopsis plants. The transgenic lines were characterized by differences in seed oil composition, and one line showed a reduction in the number of seeds counted per silique. Expression analysis revealed that the transgene was not expressed in the transgenic lines. To account for the discrepant findings, the possibility of endogenous gene silencing mechanisms suppressing transgene expression has been discussed. As an extension of this research, a second study assessed the differential expression of LEC1, LEC2, FUS3 and WRI1 in double haploid Brassica napus lines characterized by different levels of seed oil content. The expression level of the noted genes was determined at 7, 14, 21 and 28 days after pollination. Numerous changes in the transcript level were observed, but the trends were not consistent among high and low oil content lines.

Canola (Brassica napus) oil has immense economic value due to its use as food. The production of biodiesel has led to the recent increase in the demand for canola oil, and further reinforced the need to improve the oil content and composition of canola seeds. The content and quality of canola oil is dependent on the process of fatty acid biosynthesis and accumulation of triacylglycerols (TAGs) during seed development. The biochemical pathways leading to the synthesis of fatty acids and TAGs are thoroughly understood, and many of the genes encoding the metabolic enzymes involved in this pathway have been isolated and functionally characterized. Despite comprehensive understanding of fatty acid and TAG biosynthesis, alternate factors and genes involved in the modification of seed oil content and composition are being investigated. This has initiated a new sector of research focusing on a series of transcription factors: LEAFY COTYLEDON1 (LEC1), LEAFY COTYLEDON2 (LEC2), FUSCA3 (FUS3) and WRINKLED1 (WRI1), which play a key role during embryo and seed development. Previous studies in Arabidopsis have demonstrated that the noted transcription factors influence the synthesis and accumulation of oil during seed development. These findings have prompted the design of two studies with the objective of further characterizing the role of these genes. In the first study, a homolog of Arabidopsis LEC1 was isolated from Brassica napus (Bn) microspore derived embryos. BnLEC1 contained the same distinct features identified in LEC1 genes from other plant species. BnLEC1 was inserted into an expression vector, which was subsequently used to transform Arabidopsis plants. The transgenic lines were characterized by differences in seed oil composition, and one line showed a reduction in the number of seeds counted per silique. Expression analysis revealed that the transgene was not expressed in the transgenic lines. To account for the discrepant findings, the possibility of endogenous gene silencing mechanisms suppressing transgene expression has been discussed. As an extension of this research, a second study assessed the differential expression of LEC1, LEC2, FUS3 and WRI1 in double haploid Brassica napus lines characterized by different levels of seed oil content. The expression level of the noted genes was determined at 7, 14, 21 and 28 days after pollination. Numerous changes in the transcript level were observed, but the trends were not consistent among high and low oil content lines.

Thesis (M.S.)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Brett E. Olson. Includes bibliographical references (leaves 36-40).

Thesis(M.Sc.(Agriculture Horticulture)) -- University of Limpopo, 2019 / Innovative methods of preserving the quality of traditionally processed green leafy vegetables are underway in Africa. Improvement of processing and preservation methods of leafy vegetables is another way of overcoming perishability restrictions and guaranteeing continued quality food supply in rural areas. The objectives of this study were: to determine the effect of time-based oven-drying on (1) mineral composition, (2) proximate composition and (3) microbial profiling of cowpea (Vigna unguiculata). Separate experiments were conducted for raw and cooked cowpea leaves with four treatments, viz 0 (sun dried), 24, 48 and 72 hours of oven-drying, arranged in a randomised complete block design with 5 replications. In raw cowpea leaves, relative to control (sun-drying), oven-drying period 48hrs, significantly decreased Potassium (K), Manganese (Mn), and Sodium (Na) content in raw cowpea leaves by 6, 9 and 13%, respectively. Similarly, oven-drying period 72hrs significantly decreased Ca, Fe, Mg, Zn, P and S by 5, 11, 16, 18 and 57%, respectively. In cooked cowpea leaves, relative to control (sun-drying), oven-drying period 24hrs significantly increased Na by 18%. Similarly 48hrs oven-drying periods increased Fe and K by 6 and 8%, respectively. Similarly, oven-drying period 72hrs significantly increased Ca, Mg and Mn by 8, 8 and 3%, respectively. In contrast, oven-drying period 72hrs significantly reduced Zn, P and S by 16, 10 and 39%, respectively. Relative to control (sun-drying), oven-drying period 24hrs significantly increased fat by 46% in raw cowpea leaves, however oven-drying period 72hrs significantly decreased protein, moisture, ash, fibre and carbohydrate by 10, 29, 18, 0.5, and 7% respectively. In contrast, relative to control (sun-drying), 72hrs increased energy by 3%. In cooked cowpea leaves, relative to control (sun-drying), oven-drying period 24hrs significantly increased energy by 1%. In contrast, relative to control (sun-drying) 72hrs oven-drying period decreased energy by 1%. Similarly, ovendrying 72hrs significantly decreased protein, moisture, ash, fat, fibre and carbohydrate by 8, 14, 13, 19, 0.4 and 10% respectively. Relative to control (sun-drying), oven-drying periods 24hrs significantly increased Staphylococcus spp. in raw cowpea leaves by 6%, respectively. Relative to control (sun-drying) 72hrs oven-drying period significantly decreased Shigella spp. by 92%, respectively. In cooked leaves, relative to control (sundrying), 72hrs drying periods decreased both Shigella spp. and Staphylococcus spp. by 99 and 21%, respectively. Total coliforms unit of Salmonella spp, Escherichia coli, Pseudomonas spp, and Bacillus cereus were absent and/or at an undetectable level according to the Tempo Biomerieux system results. In conclusion, cooked leaves retained most essential mineral elements as compared to raw when subjected to 72hrs of oven-drying as there was an improvement in the concentration of Ca, Fe, K, Mg, Mn and Na. However, in both raw and cooked cowpea leaves proximate composition was negatively affected as there was a decrease in protein content. Oven-drying period of 24 hours can be used to minimize the loss of protein. Cooked cowpea leaves subjected to 72hrs of oven-drying had least total coliforms for both Shigella spp and Staphylococcus spp, therefore have potential to serve as an alternative to sun-drying to reduce microorganism causing spoilage in leafy vegetables. Drying raw cowpea leaves under oven-drying periods less than 72 hours should be avoided as it reduces the mineral concentration and increase microbial count of microorganisms responsible for spoilage. / National Research Foundation

LFY est un facteur de transcription clé dans le développement des plantes, et en particulier dans la floraison des angiospermes. Il a un rôle important, d'abord, dans l'établissement des méristèmes floraux et plus tard, dans la spécification de leurs identités d'organes floraux. Cette activité implique des réarrangements majeurs de la chromatine dans le noyau des cellules. Des loci cibles doivent passer d'un état fermé à un état ouvert. Au cours des deux dernières décennies, les Facteurs de Transcription Pionniers (PTF) ont été étudiés car ils peuvent lier leurs sites cibles à l'ADN nucléosomique, ils peuvent surmonter les contraintes stériques des nucléosomes et établir un état «compétent» dans une région particulière pour qu’il puisse être davantage régulé par d'autres partenaires (Iwafuchi-Doi & Zaret, 2014). Il a été démontré que LFY interagit physiquement et génétiquement avec deux ATPases appartenant à des complexes de remodelage de la chromatine ATP-dépendants, SYD et BRM (Wu et al., 2012). En outre, des analyses de données à l'échelle du génome suggèrent fortement que son domaine d'oligomérisation N-terminal, confère à LFY un accès à des régions fermées de la chromatine (Sayou et al., 2016). De cette manière, LFY présente des caractéristiques communes avec les PTF. Nous avons travaillé afin de mieux comprendre le mode d'action de LFY par rapport aux ATPases mentionnées ainsi qu'à la chromatine.Au chapitre I, à travers des expériences in vitro, l'interaction potentielle de LFY avec les nucléosomes a été évaluée. Nous avons reconstitué des nucléosomes, en identifiant des régions enrichies en nucléosomes dans le génome d'Arabidopsis, ciblées efficacement par LFY. Ces régions ont été sélectionnées à partir des données génomiques de ChIP-seq de LFY dans les lignes de surexpression ainsi que des données de DNAse-seq et de MNase-seq, qui ont été utiles pour analyser le paysage chromatinien (T. Zhang, Zhang, & Jiang, 2015; W. Zhang, Zhang, Wu, & Jiang, 2012). Une liaison forte mais non-spécifique de LFY de la gymnosperme Ginkgo biloba aux nucléosomes a été observée. Cependant, LFY d'Arabidopsis thaliana a montré une faible liaison aux nucléosomes.Au chapitre II, l'objectif était de cartographier les domaines d'interaction minimale nécessaires de LFY et les ATPases SYD et BRM. En utilisant la technique HTRF, nous avons montré que le domaine C-terminal de LFY interagit avec le domaine HSA de BRM. De plus, grâce à une approche in vivo, nous avons observé la perte du phénotype 35S:LFY dans les plantes F1 de chacun des trois croisements: 35S:LFY syd-5, 35S:LFY brm-1 et 35S:LFY brm-3. Cela suggère une interaction forte, ce qui signifie que lorsque BRM ou SYD ne sont pas fonctionnels, la fonction de LFY est affectée et aucune fleur ectopique n'est formée. / LFY is a key transcription factor in plant development, and especially in flowering for angiosperms. It has an important role, first, in the establishment of floral meristems and later, in the specification of their floral organ identities. This activity implicates on cells’ nucleus major chromatin rearrangements. Target loci need to pass from a closed to an opened state. In the last two decades, Pioneer Transcription Factors (PTFs) have been studied because they can bind their target sites at nucleosomal DNA, they are able to overcome the steric constraints of nucleosomes and establish a “competent state” in a particular region, so it can be further regulated by other partners (Iwafuchi-Doi & Zaret, 2014). LFY has been demonstrated to physically and genetically interact with two ATPases belonging to ATP-dependent chromatin remodeling complexes, SYD and BRM (Wu et al., 2012). Besides, genome-wide data analyses strongly suggest that its N-terminal oligomerization domain, confers LFY access to closed regions of chromatin (Sayou et al., 2016). In this way, LFY presents common features with PTFs. We worked in order to better understand LFY’s mode of action in relation to the mentioned ATPases as well as with chromatin.In Chapter I, through in vitro experiments, LFY’s potential interaction with nucleosomes, was assessed. We performed reconstituted nucleosomes by identifying nucleosome-enriched regions in Arabidopsis genome, efficiently targeted by LFY. These regions were selected used genome-wide data from ChIP-seq of LFY in overexpressing lines and DNAse-seq as well as MNase-seq data, which was useful to analyze chromatin landscape (T. Zhang, Zhang, & Jiang, 2015; W. Zhang, Zhang, Wu, & Jiang, 2012). A strong but non-specific binding of LFY from the gymnosperm Ginkgo biloba to nucleosomes was observed. However, LFY from Arabidopsis thaliana, showed a weak binding to nucleosomes.In Chapter II, the aim was to map the minimal necessary interacting domains of LFY and the ATPases SYD and BRM. Using the HTRF technique, LFY’s C-terminal domain was shown to interact with BRM’s HSA domain. In addition, through an in vivo approach, we observed the loss of the 35S:LFY phenotype in the F1 plants from each of the three crosses: 35S:LFY syd-5, 35S:LFY brm-1 and 35S:LFY brm-3. This suggested a strong interaction, meaning that when BRM or SYD are not functional, LFY’s function is affected and no ectopic flowers are formed.

Objectives: The aim of this study was to assess the bioaccessibility of iron and zinc in African leafy vegetables (ALV) and maize porridge composite dishes using an in vitro dialysability assay and to estimate the antinutrient content in ALV and maize porridge composite dishes. Methods: ALV leaves were collected, cooked and mixed with either cooked fortified or unfortified maize porridge to simulate the way it is usually consumed. Mineral and antinutrient levels were determined using standard methods and the bioaccessibility of iron and zinc was determined using an in vitro dialysability assay. Findings: The findings of the present study indicated that ALV dishes contain a reasonable amount of iron and zinc, but combining the ALV dishes with unfortified maize porridge resulted in dilution and hence a lower iron content. The amaranth-pumpkin dish contained most iron (24 mg/100 g). ALV dishes in the study had zinc contents ranging from 2.6 to 3.2 mg/100 g, with amaranth mixed with spider plant having the highest zinc content. Regarding antinutrients, the amaranth-cowpea dish had the highest phytate content of 2078 mg/100 g dry weight. ALV dishes also contained tannins and phenolic compounds. Iron percentage bioaccessibility was high in an amaranth-spider plant dish (25%), while other dishes had lower iron bioaccessibility of less than 11%. The percentage bioaccessibility of zinc in ALV dishes ranged from 7 to 8%. The amaranth-spider plant dish had higher zinc bioaccessibility when composited with fortified maize meal (13%). The percentage zinc bioaccessibility is negatively associated with phytate:zinc and phyate-calcium:zinc molar ratios. Conclusions: ALV and maize meal composite dishes have a high iron and zinc content, though they also have a high antinutrient content that has some inhibitory effects. Despite the inhibiting factors, the amount of bioaccessible iron and zinc from ALV and maize porridge composite dishes could play a significant role in planning food security strategies. However, there is a need to understand the possible effects of consuming them in different combinations with other foods. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

Objectives: The aim of this study was to assess the bioaccessibility of iron and zinc in African leafy vegetables (ALV) and maize porridge composite dishes using an in vitro dialysability assay and to estimate the antinutrient content in ALV and maize porridge composite dishes. Methods: ALV leaves were collected, cooked and mixed with either cooked fortified or unfortified maize porridge to simulate the way it is usually consumed. Mineral and antinutrient levels were determined using standard methods and the bioaccessibility of iron and zinc was determined using an in vitro dialysability assay. Findings: The findings of the present study indicated that ALV dishes contain a reasonable amount of iron and zinc, but combining the ALV dishes with unfortified maize porridge resulted in dilution and hence a lower iron content. The amaranth-pumpkin dish contained most iron (24 mg/100 g). ALV dishes in the study had zinc contents ranging from 2.6 to 3.2 mg/100 g, with amaranth mixed with spider plant having the highest zinc content. Regarding antinutrients, the amaranth-cowpea dish had the highest phytate content of 2078 mg/100 g dry weight. ALV dishes also contained tannins and phenolic compounds. Iron percentage bioaccessibility was high in an amaranth-spider plant dish (25%), while other dishes had lower iron bioaccessibility of less than 11%. The percentage bioaccessibility of zinc in ALV dishes ranged from 7 to 8%. The amaranth-spider plant dish had higher zinc bioaccessibility when composited with fortified maize meal (13%). The percentage zinc bioaccessibility is negatively associated with phytate:zinc and phyate-calcium:zinc molar ratios. Conclusions: ALV and maize meal composite dishes have a high iron and zinc content, though they also have a high antinutrient content that has some inhibitory effects. Despite the inhibiting factors, the amount of bioaccessible iron and zinc from ALV and maize porridge composite dishes could play a significant role in planning food security strategies. However, there is a need to understand the possible effects of consuming them in different combinations with other foods. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

Using farmer surveys the smallholder commodity systems of Brassica rapa L. subsp. chinensis and Solanum retroflexum Dun. in Vhembe District, Limpopo Province, South Africa were described and analysed. Production, transaction and consumption of the two vegetables were deeply embedded in the food, trade and farming systems of local people. The cultivation systems, which appeared effective, were developed by borrowing elements from the systems of other crops to which new knowledge specific to B. chinensis and S. retroflexum were added. Several elements of the production systems that could benefit from scientific enquiry were identified. These included genetic improvement and the optimisation of planting density and nutrient supply.