Browsing by Author "Madzivire, Panashe Kundai"

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    In vitro propagation of Haemanthus pumilio and H. albiflos (Amaryllidaceae) and the population genetics of H. pumilio
    (Stellenbosch : Stellenbosch University, 2021-04) Madzivire, Panashe Kundai; Hills, Paul N.; Dreyer, L. L.; Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics. Institute for Plant Biotechnology.
    ENGLISH ABSTRACT: Haemanthus albiflos and H. pumilio are members of the Amaryllidaceae. H. albiflos is a widespread evergreen plant, while H. pumilio is an endangered narrow endemic species with only two known populations remaining. These populations, remnants of the one recently transferred from Wellington to the Stellenbosch University Botanical gardens and another in the Duthie Reserve in Stellenbosch, present with vastly different morphologies. It is therefore vital to understand the phylogenetics and population genetics of H. pumilio as well as to design a method of in vitro propagation to increase the numbers of these plants. This study analysed the phylogenetics of H. pumilio using non-coding nuclear (Internal transcribed spacer), plastid (trnL-trnF intergenic spacer) and mitochondrial (nadi1477) gene regions and the population genetics using inter-simple sequence repeats (ISSR) and start codon targeted (SCoT) polymorphisms. The resulting phylogenetic trees revealed that H. pumilio is closely related to H. canaliculatus and H. sanguineus. The dendrograms from the DNA fingerprinting separated the two populations into distinct groups, while also revealing higher within population diversity than between them. While this is unexpected in rare narrow endemics, it might be explained by recent divergence from a more widespread species, H. sanguineus. These levels of genetic diversity are encouraging for species conservation as they suggest that intrapopulation breeding will not be detrimental to population survival. However, the two populations may become more homogenous as there exists a high level of gene flow between them. A micropropagation protocol designed using H. albiflos plants was able to successfully multiply individuals from leaf explants within 8 weeks, likely due to its ability to readily multiply by offsets. This protocol proved difficult to replicate on H. pumilio and only a single treatment with 0.1 mg/L BAP and 2 mg/L NAA differentiated after 13 weeks. However, the study was able to identify two fungal species contaminating H. pumilio cultures that could be endophytes. Future population genetics studies should aim to ascertain whether the translocation of plants from the Wellington population has increased the gene flow, thus subsequently reducing the interpopulation diversity. Additionally, this study provides crucial preliminary results on an optimum H. pumilio tissue culture method and is the first to identify possible endophytes of this species. Future micropropagation research should be conducted into providing an understanding of the plant-symbiont relationship to ascertain whether the symbionts confer necessary advantages to the plant that can be exploited to improve H. pumilio tissue culture.