Tobacco is an important crop in South Africa. The genetic basis of tobacco breeding is very narrow and cultivars are closely related. The production of new tobacco hybrids with novel characteristics through classical breeding techniques is difficult. Genetic engineering could assist plant breeders to introduce new herbicide, disease and pest resistance traits into existing proven cultivars. Plant genetic engineering has not previously been applied to the improvement of South African commercial tobacco cultivars. Agrobacterium-mediated leaf disc transformation was used to create transgenic tobacco plants from South African commercial tobacco cultivars TL33, J6 and 20/19. The cultivar samsun was also used to create transgenic plants. The Agrobacterium tumefaciens helper strain C58C1 (pGV2260) containing the binary vector pJIT119 was used to carry out the transformation. As well as the leaf disc transformation method, other methods of obtaining transgenic tobacco plants were explored. These methods included the use of Agrobacterium-mediated transformation of tobacco cell cultures and direct DNA-mediated transformation of tobacco protoplasts. The vector pJIT119 encodes the uidA gene for the β-glucuronidase (GUS) enzyme, the nptl/ gene for neomycin phosphotransferase (NPTII) and the sul I gene for the dihydropteroate enzyme conferring asulam resistance. The presence and expression of these three foreign genes uidA , npt/l and sul I from pJIT119 in transgenic tobacco plants was confirmed by a variety of experimental approaches, including the culture of transgenic plants on medium containing kanamycin or asulam, the GUS histochemical assay, the neomycin phosphotransferase assay, DNA dot-blot analysis, in situ hybridization, computerized image analysis, polymerase chain reaction and progeny analysis. A detailed analysis of individual transgenic plants is necessary in order to select those plants which express the foreign genes maximally. Only these plants would be given to plant breeders for field trial assessment. A high level of foreign gene inactivation was observed in transgenic tobacco plants obtained from the Agrobacterium-mediated leaf disc transformation method. Approximately 20% of the original transgenic plants were discarded as "escapes" as they contained a defective npt/l gene. The remaining kanamycin resistant plants, however, had inactive copies of either the sul I or the uidA gene, or both. The use of in situ hybridization and the polymerase chain reaction (PCR) helped to explain the foreign gene inactivation. The lack of foreign gene expression in individual transgenic plants was not due to the physical loss of entire foreign genes, DNA methylation or the position effect. The lack of expression was due to possible T-DNA rearrangements or deletions which disabled certain genes carried on the T-DNA. Transcription and translation of these foreign genes occurred, but the final uidA and sul I gene products (β-glucuronidase and dihydropteroate synthase, respectively) were possibly defective and did not confer GUS activity or asulam resistance on the transgenic plants The tissue specific activity of the uidA gene under the control of the cauliflower mosaic virus (CaMV) 358 promoter was studied. In the vegetative structures of transgenic tobacco plants, the uidA gene activity was located within the cells surrounding the vascular traces and within the glandular hairs. The effects of stress on 358 promoter activity was also investigated. Chemical and nutrient stess in vitro did not have a significant effect to decrease uidA gene expression under 358 promoter control. Foreign gene expression (uidA) under CaMV 358 promoter control may be enhanced by in vitro stress. Oxygen stress (anaerobic culture under waterlogged conditions) induced uidA expression in areas of the plant which usually did not show usual tissue specific patterns of uidA expression. The stage of differentiation in tissue culture when compared to the mature hardened off transgenic plant, also had an effect on the amount of uidA gene expression. Mature hardened off plants expressed less GUS activity than immature in vitro plants. The tissue specific pattern of foreign gene expression under CaMV 358 promoter direction was conserved in the reproductive structures of transgenic tobacco plants. In floral organs, the pattern of uidA gene expression was essentially the same as that found in vegetative tissues. In all floral organs examined, uidA expression was found associated with the vascular system and within the glandular hairs. The uidA gene with a CaMV 358 promoter was not expressed in pollen. Because of the ease of transformation of tobacco, it is possible that genes for pharmaceutically valuable proteins and peptides could be expressed in tobacco, for agricultural scale fine chemical production("pharming"). This could be of economic advantage for the survival of tobacco as a commercial agricultural crop in the future when tobacco smoking is no longer popular. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1994.

Thesis (MComm)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: The tobacco industry of South Africa has fallen under strict legislation and control measures from the South African government since the passing of the initial Tobacco Products Control Act, 1993. Further amendments have been made to the initial act, namely Tobacco Products Control Amendment Act, 1999 and the proposed Tobacco Products Control Amendment Bill, 2004. This assignment emerges against the backdrop of the alcoholic beverage industry coming under similar scrutiny to that of the tobacco industry from government legislation and control measures The main objective of this assignment was to discover the similarities, if any, between the tobacco industry and the alcoholic beverage industry of South Africa, specifically with regard to their advertising practices before legislation. The purpose of this assignment is to discover whether or not the alcoholic beverage industry can learn from the example of the tobacco industry in order to maintain its self-regulation, rather than to fall under the control of State regulation and legislation. The literature and empirical study sought to achieve the following four objectives: 1.) To gain a thorough understanding of the tobacco legislation on a global scale; 2.) To analyse the control measures and legislation of tobacco in a South African context; 3.) To identify any similarities between the tobacco industry and alcoholic beverage industry of South Africa and 4.) To identify means in which the alcoholic beverage industry can work with the State in order to maintain the self-regulation of its industry. Findings indicate that similarities arise when comparing tobacco and alcohol, as both of them have addictive qualities, are often used from a very young age and both have laws prohibiting sale to minors. The success gained in South Africa with regard to anti-tobacco initiatives and government legislation since the introduction of the first Tobacco Act in 1993, has led to certain members of society feeling that similar, if not the same, strict strategies and / or legislative measures should be used to address the public health problems relating to alcohol. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse tabaknywerheid val onder streng wetgewing en beheermaatreëls deur die Suid-Afrikaanse regering sedert die aanvanklike Wet op die Beheer van Tabakprodukte, 1993 aanvaar is. Verdere wysigings op die aanvanklike wet is aanvaar, naamlik die Wysigingswet op die Beheer van Tabakprodukte, 1999 en die voorgestelde Wysigingswetsontwerp op die Beheer van Tabakprodukte, 2004. Hierdie werk spruit voort teen die agtergrond van die alkoholdranknywerheid wat onder 'n soortgelyke soeklig geplaas is as die tabaknywerheid by wyse van regeringswetgewing en beheermaatreëls. Die hoofoogmerk van hierdie werk was om die ooreenkomste, indien enige, vas te stel tussen die tabaknywerheid en die alkoholdranknywerheid van Suid-Afrika, spesifiek met betrekking tot hul adverteringspraktyke vóór wetgewing. Die doel van hierdie werk was om vas te stel of die alkoholdranknywerheid uit die voorbeeld van die tabaknywerheid kan leer aldan nie, met die oog op die voortsetting van sy selfbeheer, eerder as om onder die beheer van Staatsregulering en wetgewing te val. Die bronmateriaal en empiriese studie was daarop toegespits om die volgende vier doelwitte te bereik: 1.) Om 'n behoorlike begrip te verkry van tabakwetgewing op 'n globale skaal; 2.) Om die beheermaatreëls en wetgewing oor tabak in 'n Suid-Afrikaanse konteks te analiseer; 3.) Om enige ooreenkomste tussen die tabak- en die alkoholdranknywerheid in Suid-Afrika te identifiseer en 4.) Om wyses te identifiseer waardeur die alkoholdranknywerheid met die Staat kan saamwerk om die selfbeheer van die nywerheid te behou. Bevindinge dui aan dat ooreenkomste wel ontstaan wanneer tabak en alkohol met mekaar vergelyk word, veral omdat albei verslawende eienskappe bevat, dikwels deur persone vanaf 'n baie jong ouderdom gebruik word en dat wetgewing albei verbied om aan minderjariges verkoop te word. Die sukses wat in Suid-Afrika rakende anti-tabakinisiatiewe en wetgewing behaal is sedert die inwerkingstelling van die eerste Wet op die Beheer van Tabak in 1993 het daartoe gelei dat sekere lede van die gemeenskap van mening is dat soortgelyke, indien nie dieselfde nie, streng strategieë en/of wetgewende maatreëls aangewend behoort te word om die openbare gesondheidsprobleme rakende alkohol aan te spreek.