No description available.

No description available.

No description available.

Bananas and plantains (Musa spp.) are cultivated commercially as a dessert fruit and by small-scale farmers as a staple food crop in many countries of the world. Sustainable production, however, is threatened by a number of diseases and pests such as Fusarium wilt (Fusarium oxysporum f.sp. cubense), black Sigatoka (Mycosphaerella fijiensis), the banana weevil (Cosmopolitus sordidus) and the burrowing nematode (Radopholus similis). Many diseases and pests of banana cannot be managed by conventional control methods, and replacement cultivars are often not acceptable to local industries. Resistance can be introduced into banana by means of conventional and unconventional improvement methods. Conventional breeding programs have many limitations, due to sterility of cultivated bananas, long growth cycles, low seed set and hybrids that are often not accepted by consumers. Unconventional improvement for enhanced resistance involves methods such as in vitro mutagenesis, protoplast culture, and genetic modification. During genetic modification, foreign genes are introduced into banana by means of Agrobacterium-mediated transformation or by particle bombardment. One of the most powerful means to reduce the impact of pests and diseases is the use of somatic embryogenesis for unconventional plant improvement and the propagation of disease-free plants. In this thesis, immature male flowers of Grande Naine (Musa acuminata, Cavendish subgroup, AAA) were isolated and incubated on MA1 medium to form somatic embryos with ideal callus. When ideal callus was transferred to liquid MA2 medium, a heterogeneous cell suspension was formed. Non-embryogenic aggregates were removed to ensure a cell suspension constituted of small embryogenic clusters only. Somatic embryos were obtained from the cell suspension after plating the embryogenic clusters on solid MA3 medium. These somatic embryos were transferred to MA4 medium for germination, and to P6 medium to develop into in vitro plantlets. Embryogenic cell suspension can be used for genetic engineering of disease and pest resistant plants, in vitro mutagenesis, germplasm conservation and protoplast culture. An Agrobacterium-mediated transformation system was established for the improvement of Cavendish banana cultivars, the only bananas produced for the fresh fruit market in South Africa. Embryogenic cell suspensions from the cultivar Grande Naine were co-cultivated with Agrobacterium strains harbouring the plasmids pCambia1305.1, pART-TEST7 and pKYΩOCI. Antibiotic-resistant embryos derived from transgenic cell suspensions developed into banana plantlets 12 weeks after cultivation on MA4 medium. In total, 145 putative transgenic plants were produced. Molecular analysis revealed that the Gus gene was integrated into the genome of transformed plants, and a histochemical GUS assay showed that the Gus gene was expressed in putative transgenic plants. In future, southern blot assays will be performed to determine copy numbers of the transgenes, and the putative transgenic plants containing the OcI gene tested in the greenhouse and the field for resistance to the banana weevil and the burrowing nematode. The successful transformation of Grande Naine reported in this work will contribute significantly towards improving Cavendish bananas in South Africa, and offers the opportunity to modify banana and plantain varieties cultivated in Africa for enhanced disease and pest resistance. A highly discriminative fingerprinting technique, called amplified fragment length polymorphisms (AFLPs), was used to differentiate between closely related species within the Cavendish banana subgroup. AFLP profiles of eight banana varieties, cultivars and hybrids were generated on a Licor analyser using seven different primer combinations. Results showed that the banana plants were subdivided in clades according to their genomic composition. More importantly, the AFLP technique was able to separate the different cultivars within the Cavendish subgroup. Hopefully this technique could eventually be applied to accurately detect somaclonal variants in banana due to micropropagation and genetic modification. / Dissertation (MSc)--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Genetic modification presents the potential to advance not only agricultural production but to increase quality of life as well. The potential this innovation presents will be irrelevant if the public is unwilling to accept and adopt it. The following study examines public perceptions of biotechnology, specifically the consumer approval of genetically modified food products. This study was based on data collected from a national survey conducted in both the United States and South Korea. The United States survey was designed to be nationally representative and consisted of 1201 respondents. The South Korean survey was also designed to be nationally representative and consisted of 1054 respondents Analysis was conducted using two questions from the survey questionnaire as dependent variables: (1) approval of the use of genetic modification in the creation of plant-based food products, and (2) approval of the use of genetic modification in the creation of animal-based food products. This study utilized probit models for binary choice and ordered probit models to analyze the likelihood of consumer approval of the use of genetic modification for the creation of food products. Findings indicated that consumers in the U.S. and South Korea who possessed an accurate knowledge of the applications and outcomes of GM technology were more likely to approve of its use for the creation of foods than those who had inaccurate or no knowledge of the technology. Additionally, the majority of consumers in the U.S. and South Korea believe that GM foods should be labeled as such. Those consumers who felt GM labeling to be necessary were less likely to approve of the GM of foods than those who did not feel GM labeling to be necessary. It was also found that consumers in both countries are less approving of the GM of animals than the GM of plants. Consumer approval of the use of genetic modification in the creation of food products can be increased with proper education that provides accurate knowledge of the applications of GM. Labeling of GM products is likely to result in a decrease in demand, which may be offset by public educational campaigns.

Alfalfa is an important forage crop in North America which can also escape cultivation and establish in unmanaged habitats. Genetically modified (GM) alfalfa has been approved for environmental release in Canada and the United States and the occurrence of alfalfa in unmanaged natural and semi-natural habitats may compromise the successful co-existence of GM and non-GM alfalfa. To-date, little information has been available on the nature and dynamics of roadside alfalfa populations and their ability to become feral. Such knowledge is necessary to design efficient trait confinement protocols and to enhance the co-existence of GM and non-GM alfalfa within agricultural regions. The overall aim of this work was to characterize roadside alfalfa populations and to establish their role in novel trait movement. A roadside survey revealed the widespread occurrence of feral alfalfa populations in southern Manitoba. We described the seedbanks of roadside alfalfa populations, seedling recruitment and adult reproductive success, indicating that alfalfa is capable of establishing self-perpetuating feral populations in unmanaged habitats. We also noted the successful establishment of alfalfa in a grass sward representing roadside vegetation. Roadside mowing can reduce (and perhaps prevent) seed production in roadside alfalfa; however, mowing failed to drive the populations to extinction in the short-term. Herbicide (2,4-D) applications controlled alfalfa plants but seeds in the seedbank may still contribute to new seedling recruitment. The roadside alfalfa populations we worked with exhibited high levels of genetic diversity, indicating an absence of past population bottlenecks or genetic drift. In addition, phenotypic characterization provided evidence that roadside alfalfa populations were experiencing selection pressure for adaptive traits including winter survivability, rhizome production and prostrate growth habit; all traits that favor persistence in unmanaged habitats. We also noted the occurrence of high (>60%) levels of outcrossing in feral alfalfa populations, establishing their role as sources and sinks for novel traits. Our findings indicate that alfalfa populations occurring in unmanaged habitats need to be considered in trait confinement protocols in order to reduce the adventitious presence (AP) of novel traits and to enhance the successful co-existence of GM and non-GM alfalfa.

Alfalfa is an important forage crop in North America which can also escape cultivation and establish in unmanaged habitats. Genetically modified (GM) alfalfa has been approved for environmental release in Canada and the United States and the occurrence of alfalfa in unmanaged natural and semi-natural habitats may compromise the successful co-existence of GM and non-GM alfalfa. To-date, little information has been available on the nature and dynamics of roadside alfalfa populations and their ability to become feral. Such knowledge is necessary to design efficient trait confinement protocols and to enhance the co-existence of GM and non-GM alfalfa within agricultural regions. The overall aim of this work was to characterize roadside alfalfa populations and to establish their role in novel trait movement. A roadside survey revealed the widespread occurrence of feral alfalfa populations in southern Manitoba. We described the seedbanks of roadside alfalfa populations, seedling recruitment and adult reproductive success, indicating that alfalfa is capable of establishing self-perpetuating feral populations in unmanaged habitats. We also noted the successful establishment of alfalfa in a grass sward representing roadside vegetation. Roadside mowing can reduce (and perhaps prevent) seed production in roadside alfalfa; however, mowing failed to drive the populations to extinction in the short-term. Herbicide (2,4-D) applications controlled alfalfa plants but seeds in the seedbank may still contribute to new seedling recruitment. The roadside alfalfa populations we worked with exhibited high levels of genetic diversity, indicating an absence of past population bottlenecks or genetic drift. In addition, phenotypic characterization provided evidence that roadside alfalfa populations were experiencing selection pressure for adaptive traits including winter survivability, rhizome production and prostrate growth habit; all traits that favor persistence in unmanaged habitats. We also noted the occurrence of high (>60%) levels of outcrossing in feral alfalfa populations, establishing their role as sources and sinks for novel traits. Our findings indicate that alfalfa populations occurring in unmanaged habitats need to be considered in trait confinement protocols in order to reduce the adventitious presence (AP) of novel traits and to enhance the successful co-existence of GM and non-GM alfalfa.

Sociologists have studied how organizations respond to perceived risks, but overlooked how individuals react to perceptions of organizational risks. We may expect individuals to avoid the goods and services of supposedly risky organizations, but how do other social judgments of organizations, such as those concerning reputation, relate to individuals’ risk aversion independently from their perceptions of risk? Social psychological theories on legitimacy and status and psychological theories on risk perception can bridge these gaps. Using data from the 2006 General Social Survey, this paper tests how individuals’ aversion to genetically modified foods (GMOs) relates to their perceptions of organizational risks and other qualities of business leaders, medical researchers, and political officials who are involved with producing, evaluating, and regulating GMOs. Logistic regression models find that individuals’ perceptions of medical researchers’ ignorance and disagreement about GMOs’ possible risks synergistically interact to increase the probability of rejecting GMOs. Individuals’ deferral of political influence to medical researchers attenuated the increased odds of rejecting GMOs among individuals who believe that industry scientists are disreputable. Surprisingly, perceived risks among business and political leaders were unrelated to GMO aversion. These results extend sociological risk research by demonstrating how individuals’ responses to perceived organizational risks are shaped by social characteristics such as reputations. Finally, links are drawn to inform social movement literatures and debates on GMOs, as reputational correlates exist independently from individuals’ knowledge of science, environmentalism, and generalized trust.

No description available.

In the last decade, the prevalence of genetically modified organisms (GMOs) within the American food supply has rapidly increased, with some experts estimating their presence in 80% of all U.S. food products. Unlike many other parts of the world, consumer opposition to this biotechnology has been modest in the U.S., and numerous studies have found that most Americans are unconcerned about this paradigm shift in agriculture. Although the genetic modification (GM) literature is substantial, little research has examined the role the media may play in this acquiescence, while even less has focused on the way critics and advocates of genetic modification have framed this issue. Addressing this lacuna is important because many scholars have concluded that the way an issue is framed significantly influences how an audience interprets a given message, and ultimately affects opinion formation. This study examined the websites of numerous anti-GM organizations and transnational biotech companies to determine the dominant frames they employ in their attempt to influence the American consumer. Once these frames were identified, frame analysis of the three most widely read newspapers in the country was conducted to measure the extent these frames have been employed by the U.S. print media. I hypothesized that the frames used by critics of the technology have been employed at significantly lower rates than those of advocates. This analysis suggested, however, that the way this issue has been framed in the print media is likely a less significant factor in this acquiescence than the sheer dearth of coverage generally. / Master of Science