Browsing by Author "Khunou, Angeline"

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    Specias delimitation and assessment of genetic variability in Carpobrotus (Alzoaceae): evidence from amplified fragment length polymorphisms
    (University of the Western Cape, 2004) Khunou, Angeline; Reeves, Gail; Weitz, Frans
    Species of Carpobrotus (Aizoaceae: Ruschioideae) are widely spread throughout South Africa and are commonly used for their medicinal properties. The genus consists of 13 species of which seven occur in South Africa, five in Australia and one in Chile. A number of investigations on South African species have demonstrated that some taxa exhibit anti-microbial activity. Using AFLPs (amplified fragment length polymorphisms) this study was undertaken with the primary aim of resolving relationships between Carpobrotus species in South Africa, and determining species limits by assessing their genetic distinctness. In addition, levels of genetic variability among populations of two South African species, C. acinaciformis and C. edulis werc assessed in more detail. AFLPs were not able to resolve conflict surrounding species boundaries, perhaps due to extensive hybridization. However, major groupings within South African species were identified, although no geographical structuring of these populations was evident. From a bio-prospecting perspective caution needs to be taken when sampling Carpobrotus due to difficulty in identifying species possibly as a result of hybridization.
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    Species delimitation and assessment of genetic variability in Carpobrotus (Aizoaceae): evidence from amplified fragment length polymorphisms
    (University of the Western Cape, 2004) Khunou, Angeline; Reeves, Gail
    During the course of this thesis, AFLP technique was successfully applied to the Aizoaceae taxa. This study involved a substantial component of laboratory work including generating and analysing AFLP data, the operation of an ABI377 automated DNA sequencer, and use of GeneScan and Genotyper software (Applied Biosystems). The initial motivation for this study was to reconstruct relationships between species of the genus Carpobrotus. However, it soon became clear that this would be impossible via the use of DNA sequence data. This was due to the inability to find DNA regions with sufficient variable characters for phylogenetic reconstruction. Therefore applying the AFLP fingerprinting technique to the question of species-level relationships in Carpobrotus resulted in individuals of the same species not forming distinct groups. This has subsequently led to the conclusion that gene flow is common across species boundaries in Carpobrotus as a result of hybridisation. An alternative ved may be that current species delimitations in this group are not well defined. These results also concord well with isozyme studies taxa in the Mediterranean Basin. Increased sampling of species other than C. acinaciformis and C. edulis would allow further investigation into the genetic delimitation and affinities of Carpobrotus, and shed light on the In the biotechnological age the use of molecular techniques has has the potential to greatly improve the bio-prospecting process. This has particular relevance to plants with medicinal properties, such as Carpobrotus, whereby targeted selection of genotypes with well-characterised medicinal properties may increase efficiency. Genetic and phylogenetic information can also help to identify closely related species and genera that may share similar metabolic pathways and properties. These issues are quickly coming to the forefront in the new South Africa, with the opening up of traditional knowledge systems, and subsequent integration and contact with the biotechnology community. 79