PhD Theses

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Browsing PhD Theses by Author "Elibariki, Gladness"

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    Regeneration, diversity and RNA interference strategies to enhance resistance to cassava mosaic viruses in Tanzanian manihot esc ulenta
    (University of Dar es Salaam, 2014) Elibariki, Gladness
    Cassava (Manihot esculenta) is a source of carbohydrate to more than 700 million people in the tropics and a second staple food in Tanzania. However, Cassava production in Tanzania is threatened by viruses, cassava mosaic viruses (CMV) being among the most economically important. The objectives of this study were to develop intervention strategies to control CMV through evaluation of regeneration potential and genetic diversity of Tanzanian farmer preferred cassava landraces (TFPCL) and development of RNAi constructs. Twenty one TFPCL collected from major cassava growing zones of Tanzania and used in this study were able to induce callus, 62 % being able to induce somatic embryos, 8 of them being able to regenerate to plantlets and 5 genotypes rooted on soil. Genetic diversity evaluated using 20 high polymorphic SSR markers grouped the 21 genotypes into three clusters derived from Neighbour joining analysis supported by Principal Coordinate Analysis. An average gene diversity among the genotypes was high (He=0.71) with an average heterozygozity of 0.46 and the total number of alleles across all loci was 127. Furthermore, two double stranded RNA and one antisense constructs carrying important genes for CMV replication and transcriptions were developed. The findings of this study will enhance genetic transformation efforts to combat mosaic viruses affecting cassava in Tanzania.