Thesis (M.A.)--University of Canterbury, 2004. / Typescript (photocopy). Includes bibliographical references (leaves 124-135). Also available via the World Wide Web.

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Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Biotechnology, Technikon Natal, 2002. / Lack of suitable techniques for field collection of the germplasm of different species, and spoilage of samples in transit, hinder efforts to collect, conserve, distribute and regenerate most plant germplasm in vitro. The aims of this investigation, therefore, were to address problems encountered in collection of field germplasm from species and hybrids of Eucalyptus (TAG5, TAGI4, ZG14, GC550 and GU2IO) that are propagated vegetatively and Trichilia dregeana, which has recalcitrant seeds. Simple in vitro culture-based protocols were developed to minimise contamination and maintain viability of plant material for sufficient time for it to be transported from the field to the tissue culture laboratory. From the two simulations of 48 h 'transportation' conditions for explants of Eucalyptus species investigated, those in bottles containing sterile vermiculite exhibited no contamination and greater than 50% bud break, regardless of whether or not field surface sterilization with alcohol had been done. In contrast, when explants were enclosed in cling wrap, contamination was high and bud break levels low. For selection of the more suitable Eucalyptus explant, two types were investigated: nodal explants each with one half leaf (type 1) and stem segments with three nodes (type 2). As type 2 showed considerably better shoot yields (up to 1624 shoots per 100 explant), and were more practical to use with respect to space, such trinodal stem segments were deemed best for collection. Of the sterilization procedures investigated, treatment with 70% (v/v) alcohol prior to storage was found to be most suitable in almost all cases. For plant material with high endogenous microbial contamination, the bud break medium was supplemented with Benomyl and calcium hypochlorite, each at 0.5 and 1.0 g.r). Alcoholtreated, stored explants cultured on bud break medium with 1.0 g.r) calcium hypochlorite exhibited low levels of contamination and an increased final yield (up to a maximum of 930 shoots per 100 explants). Thus, this protocol was employed for field material of E. grandis clones TAG5, TAGI4 and ZGI4. For these clones, stored type 2 explants / M

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Oat is an important crop for livestock feed and human food. Increased interest in the health promoting properties of oat has led to a need to explore diverse oat germplasm for improved nutritional quality. One target for improved nutritional quality could be an altered fatty acid composition. A study was conducted to explore the fatty acid profile of diverse accessions from the world oat collection preserved in the Canadian national seed genebank, Plant Gene Resources of Canada (PGRC), at the Agriculture and Agri-Food Canada (AAFC) Research Centre, Saskatoon, Saskatchewan, Canada and genotypes from the Crop Development Centre (CDC), University of Saskatchewan, Saskatoon and the Eastern Cereal and Oilseed Research Centre (ECORC), AAFC, Ottawa, Canada. Accessions included a wide range of Avena sativa L. and other selected species from the genus Avena (A. byzantina C. Koch, A. sterilis L., A. fatua L., A. sativa subsp. nudisativa (Husn.) Rod. et. Sold. and A. strigosa Schreb.). The fatty acid profiles of 917 oat accessions from these taxa were analyzed using gas chromatography, revealing significant variability for the three major fatty acids in oat oil. Oleic and linoleic acid demonstrated the greatest variation. A few A. sativa accessions had higher oleic and lower palmitic acid levels compared to the general average. Some hexaploid wild oat accessions (A. sterilis) showed relatively high oleic and below average levels of palmitic and linoleic acid compared to A. sativa. A. strigosa accessions had consistently higher levels of oleic acid than other Avena species. Based on initial results, 52 selected A. sativa accessions were grown in 2009 in replicated field trials and re-evaluated to gain insight into the influence of the growing environment on fatty acid composition. Fatty acid composition was affected by genotype, whereas location significantly affected palmitic and oleic acid content. Correlations were determined among the contents of the six fatty acids, oil content and protein content. Oleic acid content was positively correlated with oil content, which may be particularly important to plant breeders for nutritional quality improvement of future oat cultivars. The understanding gained from this research suggests the possibility of improving the fatty acid profile of future oat cultivars for food and feed.

Oat is an important crop for livestock feed and human food. Increased interest in the health promoting properties of oat has led to a need to explore diverse oat germplasm for improved nutritional quality. One target for improved nutritional quality could be an altered fatty acid composition. A study was conducted to explore the fatty acid profile of diverse accessions from the world oat collection preserved in the Canadian national seed genebank, Plant Gene Resources of Canada (PGRC), at the Agriculture and Agri-Food Canada (AAFC) Research Centre, Saskatoon, Saskatchewan, Canada and genotypes from the Crop Development Centre (CDC), University of Saskatchewan, Saskatoon and the Eastern Cereal and Oilseed Research Centre (ECORC), AAFC, Ottawa, Canada. Accessions included a wide range of Avena sativa L. and other selected species from the genus Avena (A. byzantina C. Koch, A. sterilis L., A. fatua L., A. sativa subsp. nudisativa (Husn.) Rod. et. Sold. and A. strigosa Schreb.). The fatty acid profiles of 917 oat accessions from these taxa were analyzed using gas chromatography, revealing significant variability for the three major fatty acids in oat oil. Oleic and linoleic acid demonstrated the greatest variation. A few A. sativa accessions had higher oleic and lower palmitic acid levels compared to the general average. Some hexaploid wild oat accessions (A. sterilis) showed relatively high oleic and below average levels of palmitic and linoleic acid compared to A. sativa. A. strigosa accessions had consistently higher levels of oleic acid than other Avena species. Based on initial results, 52 selected A. sativa accessions were grown in 2009 in replicated field trials and re-evaluated to gain insight into the influence of the growing environment on fatty acid composition. Fatty acid composition was affected by genotype, whereas location significantly affected palmitic and oleic acid content. Correlations were determined among the contents of the six fatty acids, oil content and protein content. Oleic acid content was positively correlated with oil content, which may be particularly important to plant breeders for nutritional quality improvement of future oat cultivars. The understanding gained from this research suggests the possibility of improving the fatty acid profile of future oat cultivars for food and feed.

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Tobacco mosaic virus (TMV) infects all classes of tobacco (Nicotiana tabacum L.) and causes losses worldwide. The N gene is the most effective means of controlling TMV; however, this gene is associated with reduced yield and quality in flue-cured tobacco. The mode of inheritance of TMV resistance was determined in two tobacco introductions (TI) from N. tabacum germplasm, both of which produced a hypersensitive response when inoculated with TMV. Inheritance studies with TI 1504 and TI 1473 indicate that a single dominant gene controls resistance. The gene governing resistance in TI 1504 is allelic to the N gene in NC 567. The gene providing resistance in TI 1473 is not allelic to the N gene, providing a potentially new source of resistance. Currently, plant breeders must rely on the N gene. The N gene is used in the heterozygous state to help overcome poor agronomic effects associated with homozygous resistance; however, systemic movement of TMV is occasionally seen in resistant plants. A TMV susceptible inbred (K 326), a resistant inbred (NC 567), and three resistant hybrids (NC 297, RGH4, and Speight H2O) were inoculated with TMV at transplanting, layby, and topping using different inoculation methods. Plant parts were tested for viral presence and biological activity. Viral movement into all plant parts was observed in K 326. No systemic movement was evident in the plant parts of NC 567, while virus did move into the corollas, pistils, late season sucker growth, and roots of the resistant hybrids showing systemic necrosis. / Master of Science

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