Recentes estudos genômicos têm mostrado que vários fungos e bactérias possuem um potencial biossintético superior à quantidade de me tabólitos secundários já isolados desses micro-organismos. A descoberta de produtos naturais inéditos e bioativos é limitada pela impossibilidade dos micro-organismos expressarem to das as suas rotas biossintéticas em laboratório. Assim, estratégias alternativas para i nduzir a produção de produtos naturais microbianos são necessárias. A utilização de cultur as mistas de micro-organismos é uma estratégia que vem sendo recentemente utilizada, na tentativa de mimetizar condições mais naturais de crescimento. Além disso, a adição de mo duladores químicos e epigenéticos às culturas microbianas também pode potencialmente est imular a produção de compostos de interesse, seja por ativar mecanismos celulares em resposta à condição de estresse, ou por alterar a taxa de transcrição de certos genes, em f unção de mudanças no grau de enovelamento da cromatina. Alternativamente, a indu ção de certos genes, e até mesmo a diversificação do metabolismo secundário, podem ser conseguidos através de engenharia genética, pela manipulação direta de genes de inter esse. A linhagem endofítica Alternaria tenuissima SS77, selecionada para os experimentos de modulaçã o química e epigenética, teve seu metabolismo secundário alterado após o tra tamento com diferentes moduladores. Provavelmente, o efeito observado ocorreu em função de uma eliciação inespecífica dos diferentes moduladores. Além disso, o cultivo misto desse fungo com o fungo endofítico Nigrospora sphaerica SS67 , isolada da mesma planta hospedeira ( Smallanthus sonchifolius ), levou ao isolamento de dois novos policetídeos, da classe das perilenequinonas, juntamente com um já relatado na literatura científica. Para r ealizar os cultivos microbianos mistos, envolvendo uma linhagem bacteriana e uma fúngica, t rês linhagens de actinobactérias e cinco de fungos, todos endofíticos da planta Lychnophora ericoides , foram selecionadas. Alterações no perfil metabólico da cultura mista de Phomopsis sp FLe6 com Streptomyces albospinus RLe7 foram as mais evidentes e por isso a maioria das investigações foram focadas nessa cultura mista. Várias condições de cu ltivo foram testadas e diferentes resultados foram obtidos. Em alguns casos, o desenv olvimento da linhagem fúngica foi inibido pela bacteriana, e em outros, foi observado o inverso. Da mesma forma, houve acentuada inibição da produção de alguns metabólito s secundários na presença da linhagem desafiadora, mas também foi verificada a eliciação de outros. Os extratos das culturas simples desses micro-organismos também apresentaram relativas alterações nos perfis metabólicos em função das condições de cultivo. Os metabólitos produzidos pelo fungo Phomopsis sp FLe6 e pela actinobactéria Streptomyces albospinus RLe7 foram isolados e caracterizados. Os resultados mostram que as intera ções entre os micro-organismos endofíticos são bastante complexas, estando sujeita s a ação de diversos fatores externos que muitas vezes não podem ser pré-determinados. Po r isso, estabelecer um cultivo misto adequado, do ponto de vista da eliciação da produçã o de metabólitos secundários, pode requerer uma série de tentativas. Ainda assim, os r esultados almejados podem ser conseguidos utilizando essa estratégia. Diferenteme nte das linhagens endofíticas, manipuladas quimicamente através de diferentes estr atégias, a linhagem sequenciada de Fusarium heterosporum ATCC 74349, foi manipulada geneticamente para a co nstrução de um gene biossintético híbrido pks-nrps , contendo a porção nrps do gene híbrido da equisetina e um pks críptico de Aspergillus fumigatus . Era esperado que a linhagem hibridizada fosse capaz de produzir o metabólito se cundário geneticamente planejado, entretanto, após seu cultivo, esse produto não foi detectado nos extratos, e as possíveis razões são discutidas. Ainda que os resultados espe rados não tenham sido obtidos, estudos que contribuam para a ampliação do entendimento das megassintases fúngicas são de extrema valia. / Recently, genetic studies have shown that several b acteria and fungi hold a greater biosynthetic potential than the amount of secondary metabolites isolated from these microorganisms. The discovery of novel bioactive na tural products is limited by the inability of microorganisms to express all their biosynthetic pa thways in laboratory conditions. Therefore, alternative strategies to induce the production of microbial natural products are required. Mixed cultures of microorganisms are a strategy tha t has been used to mimic more natural conditions of growth. Furthermore, the addition of chemical and epigenetic modulators to the microbial cultures can also stimulate the productio n of compounds by activating cellular mechanisms in response to stress conditions or by c hanging the transcription rate of certain genes, due to changes in the chromatin folding. Alt ernatively, the induction of some genes, and even the diversification of secondary metabolis m, can be achieved by genetic engineering, by manipulating genes of interest. The endophytic strain Alternaria tenuissima SS77, which was selected for the experiments of che mical and epigenetic modulation, had changed its secondary metabolism after treatment wi th different modulators. Probably, the observed effect was due to a nonspecific elicitatio n of those modulators. Moreover, the mixed cultures of this fungus with the endophytic fungus Nigrospora sphaerica SS67, isolated from the same host plant ( Smallanthus sonchifolius ), led to the isolation of two new polyketides, belonging to perylene quinone class, along with ano ther one already reported in the scientific literature. Three strains of actinobacteria and fiv e fungi, all endophytes of Lychnophora ericoides , were selected to grow in microbial mixed cultures comprising one bacteria and one fungus. Changes in the metabolic profile of the mix ed culture of Phomopsis sp. FLe6 with Streptomyces albospinus RLe7 were the most obvious, and then further studi es were focused on this mixed culture. Many culture conditions were analyzed and different results were obtained. In some cases, the development of the fun gal strain was inhibited by bacteria, and in other cases was observed the opposite. Similarly , there was a remarkable inhibition of the production of certain secondary metabolites in the presence of the challenging strain, but the eliciting of others was also observed. The extracts of the single cultures of these microorganisms also showed changes in metabolic pro files due to culture conditions. The metabolites produced by the fungus Phomopsis sp. FLe6 and the actinobacteria S. albospinus RLe7 were isolated and characterized. The results show that interactions between endophytic microorganisms are quite complex and are influenced by various external factors that often can not be previously determined. Theref ore, establishing a suitable mixed culture to elicit the production of secondary metabolites m ay require some attempts. Still, the expected results can be achieved using this strateg y. Unlike the endophytic strains, that was chemically manipulated by different strategies, the sequenced strain Fusarium heterosporum ATCC 74349 was genetically manipulated to construct a hybrid PKS-NRPS biosynthetic gene containing the NRPS portion of the hybrid gene of e quisetin and a cryptic PKS gene of Aspergillus fumigatus . It was expected that hybridized strain could be a ble to produce the secondary metabolite genetically planned, however, after its cultivation, this product was not detected in any extracts, and some possible reasons are discussed. Although the expected results have not been obtained, studies that contri bute to increasing the understanding of fungal megasynthases are extremely valuable

A number of morphological, floral, rhizome, root and herbage characteristics were studied in order to describe genetic variation and environmental responses in T. ambiguum. From each of six lines, 30 genotypes were clonally progagated into five diverse edaphic and altitudinal sites and grown for one season. Comparisons of growth and form were also made between T. ambiguum, T. repens cv. 'Grasslands Huia' and Lotus pedunculatus cv. 'Grasslands Maku'. The polyploid lines were found to have larger leaves than the diploids while all the lines of T. ambiguum had larger leaves than did white clover. Tetraploid lines had longer petioles and were taller and more erect than the diploids or hexaploids. Floral initiation was found to become later as ploidy level increased but the tetraploid lines exhibited a very large variation in flowering date. The cultivar Treeline was found to produce the most herbage under all conditions although not significantly more than cultivar Prairie or C.P.I. 57353. However, as nodulation was not studied it was not possible to determine whether variety differences were due to root nodulating ability or some other genetically determined parameter. None of the T. ambiguum varieties produced as much herbage as cv. Huia or cv. Maku at any site. However, all the T. ambiguum lines performed relatively better under harsher conditions. Because a large proportion of T. ambiguum was below ground the best T. ambiguum line, cultivar Treeiine, produced equivalent total plant dry weight to cv. Huia and cv. Maku at 1200 m. a.s.l., the high altitude site. Cultivar Prairie was found to have the highest proportion of rhizomes to total plant mass bu because cv. Treeline had higher total plant dry weight both cultivars produced equivalent mean rhizome dry weight. The number of rhizomes, number of daughter plants and rhizome dry weight were all highly correlated and these three characteristics showed similar trends among varieties. Rhizome length was found to increase with ploidy level, as did rhizome internode length. However, the number of nodes was found to be higher in the diploids than in the polyploids. Cultivar Treeline was found to have a high proportion of branching nodes on its rhizomes while C.P.I. 57353 and cv. Summit had the least. Rhizome production was restricted in the Wakanui silt loam soil of high bulk density. However, herbage growth and rhizome branching was increased, probably because of the higher fertility. It was shown using factor analysis on genotypic correlations, that rhizome characteristics and herbage yields were relatively independently inherited. However, morphological characters tended to be related to herbage yields. The polyploid varieties were found to be more genetically variable than the diploids . Broad sense heritabilities were calculated for all parameters measured, and in general, morphological characteristics had higher values than agronomic characteristics. As the genetic variation within each line was higher than the variation among lines, it is apparent that selection within lines should result in the largest gains. Therefore, comparison of the mean performance of the presently highly variable lines is relatively uninformative. By sacrificing some genetic diversity, large gains could be made in performance. It is suggested that cv. Prairie be used as the basis for selecting a highly rhizomatous cultivar while cv. Treeline could be used in the selection of a cultivar with higher herbage production suitable for high country conditions. In a second trial, an established stand of cv. Treeline produced up to 13250 kg ha⁻¹ for one season under good growing conditions. The management required to produce this amount of herbage was to irrigate and cut to ground level every two months. The growth rate was considerably depressed when cut monthly. It was also shown that root and rhizome yield reached 12600 kg ha⁻¹, indicating a massive reserve of assimilates, particularly useful for surviving periods of stress. Seed yields were found to be adequate, reaching levels equivalent to 500-700 kg ha⁻¹. These results were discussed in relation to earlier observations on T. ambiguum by workers in Russia, Australia, U.S.A. and New Zealand. Suggestions were made for further genetic and agronomic testing.

Some aspects of the presence of systemic endophytic fungi in agriculturally important New Zealand grasses were studied in relation to plant breeding. Seedling resistance to adult Argentine stem weevil feeding in perennial ryegrass, Italian ryegrass and tall fescue was found to be related to the presence of their respective Acremonium endophytes in the seed rather than to plant genetic resistance. In addition a study of perennial ryegrass revealed that this resistance was independent of endophyte viability. The seedling resistance conferred by the endophyte of Italian ryegrass was found to be beneficial for field establishment. This endophyte differs from that in perennial ryegrass and tall fescue in that it does not confer resistance to Argentine stem weevil on mature plants, but only on seedlings. The extent of plant genetic seedling tolerance to adult Argentine stem weevil feeding was limited to broad inter-specific differences, with tall fescue more tolerant than perennial ryegrass and both of these more tolerant than Italian ryegrass. This ranking corresponds with previous observations on feeding preference on mature plants. A study of factors affecting the concentration of endophyte mycelia in infected seed of perennial ryegrass revealed that plant genetic factors had little effect. The major factors studied were: 1) the endophyte concentration in the maternal parent plant directly influenced the endophyte concentration in the seed. 2) nitrogen fertilizer applications to a seed crop reduced the concentration of mycelia in the seed, with earlier applications having a greater effect. 3) application of the fungicide propiconazole (Tilt) to a seed crop reduced the endophyte concentration in the seed. 4) the endophyte concentration in the seed was found to directly influence the endophyte concentration in seedlings, six month old plants and that of seed harvested from a first year seed crop. As there have been no previous reports of tetraploid perennial ryegrass cultivars with endophyte an experiment was conducted to determine if these could be developed by the standard procedure of colchicine treatment. The results revealed that endophyte was retained following colchicine treatment.

This thesis is presented in the form of a series of papers some of which have already been published. It is prefaced by a review of research on the agronomy and physiology of wheat yield in New Zealand, and concluded with a general discussion, Other relevant papers in which the author was a contributor may be found in the Appendix. / Between 1972 and 1976 a series of field experiments were conducted to investigate the factors limiting grain yield in wheat (Triticum aestivum L). Spike population restricted yield when it was below about 500 spikes/m² but once it exceeded 700/m² grain yield declined due to a reduction in the number of grains per spikelet. Irrigation, high sowing rate, and nitrogen fertiliser generally increased spike number but the effects on the number of grains/spikelet were variable, apparently depending on processes related to leaf area index. The semi-dwarf Karamu outyielded New Zealand wheats when spring-sown because it produced more spikelets/spike and more grains/ spikelet than the other cultivars. The superior grain set of Karamu was because more of the distal florets within each spikelet produced grain than in the other cultivars. The results are discussed in relation to cultural practices and plant breeding.

Variables for the accelerated ageing (AA) test, methods for reducing fungal contamination during the AA test, using the conductivity test as a vigour test, the effect of seed size on seed vigour and the relationship between laboratory test results and field perfonnance in selected Brassica spp were investigated. In the first experiment, three seed lots of turnip rape hybrid (B. rapa x campestris), turnip (B. campestris) and forage rape (B. napus); and seven seed lots of Asian rape (B. napus), six seed lots of Asian kale (B. oleraceae var. alboglabra L.) and five seed lots of choisum (B. rapa var. pekinensis) with germinations above 90% were aged at two different temperatures (41 and 42°C ± 0.3°C) and three ageing times (24, 48 and 72 ± 15 minutes). The second experiment was divided into three sections. In the first, the same seed lots and species were aged at one temperature (41°C) and time (72 h), but either 40 ml of saturated salts; KCl (83%RH), NaCl (76%RH), NaBr (55%RH); or distilled water (96%RH) were used as the ageing solutions. In the second, one turnip rape hyprid seed lot was aged at three temperatures (41, 42 and 45°C) and two times (72 and 96h), again using the three saturated salts and distilled water as ageing solutions. In the third, three turnip rape hybrid seed lots and three Asian kale seed lots were surface sterilised (1 % sodium hypochlorite) prior to ageing at one temperature (41°C) and time (72 h). In the third experiment, the same species and seed lots used in experiment one at their original seed moisture content (SMC) were tested for conductivity after soaking in deionised water for 4, 8, 12, 16, 20 and 24 h. They were then re-tested after the SMC had been adjusted to 8.5%. In the fourth experiment, three seed lots of forage rape and three seed lots of Asian kale were graded into three seed size categories; large (retained on a 2.0 mm screen), medium (retained on a 1.7 mm screen) and small (passed through a 1.7 mm screen). Graded seeds were then tested for standard germination, AA (41°C/48 h) and conductivity (measured at 16 and 24 h). In the final experiment, the relationships between laboratory tests for the six species (each consisting of three seed lots), field emergence from three sowings, and cold room emergence were evaluated. Both time and temperature influenced post-AA germination. Increasing the ageing period from 48 to 72 hours at 41°C, and 24 to 48 hours at 42°C resulted in decreased mean germination percentage for all species but not always clear separation of seed lots. While there were sometimes few differences between ageing at 41°C and 42°C, the former is preferred because it is already the temperature used for other species. For Asian rape, choisum and turnip, the previously recommended testing conditions of 41°C/72 h provided good seed lot separation, but for Asian kale and turnip rape hybrid, AA testing at 41°C/48 h provided better results. Seed moisture content after ageing ranged from 29-37% depending on species. Fungal growth on seeds during the ageing period appeared to reduce post-ageing germination in some seed lots . Substituting saturated salts for distilled water did not stress seed lots in the AA test, due to the lowered RH%, the exception being seed lots 1210 and 1296. For forage and Asian species, seed lot germination mostly remained above 90% when aged for 72 h at lowered RH%. Increasing the ageing duration from 72 to 96 hours resulted in some decreases in post-AA germination but no clear separation of seed lots. Surface sterilising the seeds prior to the AA test resulted in a lower incidence of contaminant fungi which was associated with a lower percentage of abnormal seedlings. The conductivity test was mostly able to identify vigour differences among forage and Asian vegetable brassica seed lots. Differences in conductivity readings were observed among seed lots in all species. Increasing the period of imbibition resulted in increased conductivity from most seed lots but radicle emergence occurred after 16-20 h of imbibition. Variation was observed in the time to reach 95% maximum of the imbibition curve for most species. Conductivity readings at 16 h would avoid possible influences of radicle emergence on results. Adjusting the SMC to 8.5% resulted in reduced variation in conductivity among replicates of seed lots, due to a reduction in imbibition damage. Seed size had a significant effect on both post-AA germination and conductivity results. In forage rape, large size seeds had higher post-AA germination cf. medium cf. small size seeds. In Asian kale, large size seeds had higher post-AA germination compared with small size seeds. For both forage rape and Asian kale, large size seeds had lower conductivity readings cf. small size seeds. The correlation analyses demonstrated significant relationships between AA testing and field emergence parameters (percentage emergence, emergence index and emergence rate). Significant relationships were also observed between conductivity testing and these field emergence parameters. Based on the correlation analysis, AA testing at 41°C/48 hand/or 42°C/48 h could be recommended to be used as an AA test for turnip and Asian rape; and 41°C/48 hand/or 41°C/72 h for Asian kale and choisum. Based on the correlation analysis, conductivity testing at 16 h can be used to predict the field emergence potential of forage and Asian vegetable seed lots. Vigour tests were consistently able to provide better indicators of field perfonnance than the standard germination test, although these relationships did vary with the different field sowings.

The permanent pasture based on a grass-clover association and utilised in situ by grazing stock is the basis of New Zealand's chief primary industries. Although white clover is the main legume species used for this purpose its production and persistence in the drier eastern areas of the South Island often leaves much to be desired. In such situations subterranean clover may provide a useful alternative. Subterranean clover has been a very useful species in the past and will probably continue to play an important role in the future, provided the most climatically adapted cultivars are grown. The aim of the field trials was to evaluate the productive performance of several subterranean clover cultivars in Canterbury. Because of the big influence of seed yield on subsequent production and persistence in annuals, this aspect was also investigated. The subterranean clover cultivars Geraldton, Yarloop, Woogenellup, Clare, Mt. Barker and Tallarook were evaluated under cutting in swards at two sites in Canterbury.

Genetic variation is a strong risk factor for many human diseases, including diabetes, cancer, cardiovascular disease, depression, autoimmunity and asthma. Most of the disease genes identified so far alter the amino acid sequences of encoded proteins. However, a significant number of genetic variants affecting complex diseases may alter the regulation of gene transcription. The map of the regulatory elements in the human genome is still to a large extent unknown, and it remains a challenge to separate the functional regulatory genetic variations from linked neutral variations. The objective of this thesis was to develop methods for the identification of genetic variation with a potential to affect the transcriptional regulation of human genes, and to analyze potential regulatory polymorphisms in the CD36 glycoprotein, a candidate gene for cardiovascular disease. An in silico tool for the prediction of regulatory polymorphisms in human genes was implemented and is available at www.cisreg.ca/RAVEN. The tool was evaluated using experimentally verified regulatory single nucleotide polymorphisms (SNPs) collected from the scientific literature, and tested in combination with experimental detection of allele specific expression of target genes (allelic imbalance). Regulatory SNPs were shown to be located in evolutionary conserved regions more often than background SNPs, but predicted transcription factor binding sites were unable to enrich for regulatory SNPs unless additional information linking transcription factors with the target genes were available. The in silico tool was applied to the CD36 glycoprotein, a candidate gene for cardiovascular disease. Potential regulatory SNPs in the alternative promoters of this gene were identified and evaluated in vitro and in vivo using a clinical study for coronary artery disease. We observed association to the plasma concentrations of inflammation markers (serum amyloid A protein and C-reactive protein) in myocardial infarction patients, which highlights the need for further analyses of potential regulatory polymorphisms in this gene. Taken together, this thesis describes an in silico approach to identify putative regulatory polymorphisms which can be useful for directing limited laboratory resources to the polymorphisms most likely to have a phenotypic effect.

No description available.

Sweet potato (Ipomoea batatas Lam.) is ranked as the seventh most important food crop in the world and its large biomass and nutrient production give it a unique role in famine relief. However, multiple virus infection is the main disease limiting factor in sweet potato production worldwide. The main objective of this research project was to develop a transgenic sweet potato cultivar with broad virus resistance in South Africa (SA). A review of current literature assembled background information pertaining to the origin, distribution and importance of the sweet potato crop; viruses and complexes infecting sweet potato; and the strategies used in sweet potato virus detection and control. A survey to determine the occurrence and distribution of viruses infecting sweet potato (Ipomoea batatas Lam.) was conducted in major sweet potato-growing areas in KwaZulu-Natal (KZN). A total of 84 symptomatic vine samples were collected and graft inoculated onto universal indicator plants, Ipomoea setosa Ker. and Ipomoea nil Lam. Six weeks post inoculation, typical sweet potato virus-like symptoms of chlorotic flecking, severe leaf deformation, stunting, chlorotic mosaic, and distinct interveinal chlorotic patterns were observed on indicator plants. Under the transmission electron microscope (TEM), negatively stained preparations of crude leaf sap and ultra-thin sections from symptomatic grafted I.setosa plants revealed the presence of elongated flexuous particles and pinwheel type inclusions bodies‟ that are characteristic to the cytopathology of Potyviruses. Symptomatic leaf samples from graft-inoculated I. setosa and I. nil were assayed for Sweet potato feathery mottle virus (SPFMV), Sweet potato mild mottle virus (SPMMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato chlorotic fleck virus (SPCFV), Sweet potato virus G (SPVG), Sweet potato mild speckling virus (SPMSV), Sweet potato caulimo-like virus (SPCaLV), Sweet potato latent virus (SPLV), Cucumber mosaic virus (CMV), and Sweet potato C-6 virus (C-6) using the nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA). The majority of leaf samples (52%) tested positive for virus disease and showed the occurrence of SPFMV, SPMMV, SPCSV, SPCFV, SPVG, SPMSV, and SPCaLV. Of these 7 viruses, the most frequently detected were SPFMV (39%), SPVG (30%), followed by SPCSV (13%) and SPMMV (12%). SPCaLV and SPCFV at 10% and SPMSV at 7% were found exclusively in samples collected from one area. SPFMV, SPVG, SPCSV, and SPMMV were identified as the most prevalent viruses infecting sweet potato in KZN. The genetic variability of the three major viruses infecting sweet potato (Ipomoea batatas Lam.) in KZN was determined in this study. A total of 16 virus isolates originating from three different locations (Umbumbulu, Umfume and Umphambanyomi River) in KZN were analyzed. These comprised of 10 isolates of Sweet potato feathery mottle virus (SPFMV), five isolates of Sweet potato virus G (SPVG) and one isolate of Sweet potato chlorotic stunt virus (SPCSV). The phylogenetic relationships of the SPFMV, SPVG and SPCSV isolates from KZN relative to isolates occurring in SA and different parts of the world were assessed. The division of SPFMV into four genetic groups (strains) according to the phylogenetic analysis of coat protein encoding sequences revealed mixed infections of the O (ordinary) and C (common) strains in sweet potato crops from KZN. All SPFMV isolates showed close lineage with isolates from South America, East Asia and Africa. The SPVG isolates showed high relatedness to each other and close lineage with other isolates, especially those from China and Egypt. Analysis of the partial sequence of the Heat shock protein 70 homologue (Hsp70h) gene indicated that the SPCSV isolate from KZN belongs to the West African (WA) strain group of SPCSV and showed close relatedness to an isolate from Argentina. The knowledge of specific viral diversity is essential in developing effective control measures against sweet potato viruses in KZN. Multiple virus infections of Sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato virus G (SPVG) and Sweet potato mild mottle virus (SPMMV) cause a devastating synergistic disease complex of sweet potato (Ipomoea batatas Lam.) in KZN. In order to address the problem of the multiplicity and synergism of sweet potato viruses in KZN, this study aimed to develop transgenic sweet potato cv. Blesbok with broad virus resistance. An efficient and reproducible plant regeneration protocol for sweet potato (Ipomoea batatas Lam.) cultivar Blesbok was also developed in this study. The effect of different hormone combinations and type of explants on shoot regeneration was evaluated in order to optimize the regeneration protocol. Coat protein (CP) gene segments of SPFMV, SPCSV, SPVG and SPMMV were fused to a silencer DNA, the middle half of the nucleocapsid (N) gene of Tomato spotted wilt virus (TSWV) and used as a chimeric transgene in a sense orientation to induce gene silencing in the transgenic sweet potato. Transformation of apical tips of sweet potato cv. Blesbok was achieved by using Agrobacterium tumefaciens strain LBA4404 harboring a modified binary vector pGA482G carrying the plant expressible neomycin phosphotransferase ll gene (nptll), the bacterial gentamycin-(3)-N-acetyl-transferase gene and the expression cassette. A total of 24 putative transgenic plants were produced from the transformed apical tips via de novo organogenesis and regeneration into plants under 50mg/L kanamycin and 200 mg/L carbenicillin selection. Polymerase chain reaction (PCR) and Southern blot analyses showed that six of the 24 putative transgenic plants were transgenic with two insertion loci and that all plants were derived from the same transgenic event. The six transgenic sweet potato plants were challenged by graft inoculation with SPFMV, SPCSV, SPVG and SPMMV- infected Ipomoea setosa Ker. Although virus presence was detected using NCM-ELISA, all transgenic plants displayed delayed and milder symptoms, of chlorosis and mottle of lower leaves when compared to the untransformed control plants. These results warrant further investigation under field conditions. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

In this Master of Arts Thesis in Anthropology I examine the controversy in the Okanagan Valley over the introduction of GM seed technologies into local agricultural processes. I explore via a multi-sited ethnography how local fruit farmers in this region view GM seed technologies and their perception of how these technologies will impact their farming practices. I argue that (a) the use of GM seeds as currently regulated in Canada threatens to erode farmers' local knowledge of plant breeding and that (b) this erosion is of consequence not only to local farmers but to society generally because the environmental knowledge and skills possessed by local farmers is crucial to the protection of biodiversity, environmental sustainability, and food security.