Browsing by Author "Elibariki, Gladness"

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    Evaluation of Regeneration Potentials of Farmerpreferred Cassava (Manihot Esculenta Crantz) Landraces to Unlock Cassava Transformation Barriers
    (2014) Elibariki, Gladness; Lupembe, M.; Hosea, Ken M.; Ndunguru, Joseph
    Evaluation of cassava germplasms for in vitro regeneration ability is crucial for stable genetic improvement of this crop via genetic transformation systems. Methods for reliable and efficient transformation including somatic embryo regeneration and recovery of transgenic plants still need to be developed and customized for each cassava genotype. Twenty one Tanzanian farmer- preferred cassava (Manihot esculenta Crantz) landraces widely grown in major cassava growing zones were evaluated for somatic embryo induction, recovery, sustainability and plantlets regeneration to whole plants. Somatic embryogenesis was induced from cassava leaf lobes on Murashige and Skoog media supplemented with different concentrations of sucrose, Copper sulphate and 2, 4-Dichlorophenoxyacetic acid and further developed to plantlets. Frequency of somatic embryo production and subsequently regeneration stages were evaluated starting from 28 days post-inoculation. All cassava genotypes tested in this study were able to induce callus where by 62 % were able to induce somatic embryo cotyledons. Cassava landraces: Sagalato, Rangimbili, Mnazi and Kibandameno were highly responsive to somatic embryo production. The conversion rate of embryos into plantlets was variable depending on the cassava landrace, Sagalato being the most responsive and Kiroba the least. Somatic embryos from 8 cassava landraces reached plantlet stage, 5 of them being acclimatized and successfully developed to plants with normal phenotype and they rooted on soil. The regeneration potentials of farmer-preferred cassava landraces observed in this study is hoped to pave a way towards genetic improvement for both biotic and abiotic stresses via genetic engineering approaches.
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    Genetic Diversity and Identification of Duplicates in Selected Tanzanian Farmerpreferred Cassava Landraces Using Simple Sequence Repeat (SSR) Markers
    (2013) Elibariki, Gladness; Njahira, Moses; Wanjala, Bramwel W.; Hosea, Ken M.; Ndunguru, Joseph
    Genetic variation at twenty simple sequence repeat (SSR) markers loci was used to evaluate 21 Tanzanian farmerpreferred cassava landraces collected and maintained at Mikocheni Agricultural Research Institute laboratory in Tanzania.Two West African cassava genotypes and one Kenyan cassava were included in the clustering analysis. Genotyping with twenty high polymorphic SSR markers grouped the genotypes into three clusters derived from Neighbour joining analysis. Clustering analysis was well supported by principle component analysis (PCA). The first three axes of PCA with positive Eigen values accounted for 22.76, 15.93 and 8.48 % of the total variations respectively. No genotype duplicates were detected among the cassava landraces. Average gene diversity among the Tanzanian cassava was high (0.71) with an average heterozygozity of 0.46. Total number of alleles across all loci was 127 with mean number of alleles per locus being 6.35 and SSR markers had a mean polymorphic information content of 0.67. The results obtained in this study facilitated on selection of genotypes to include in the ongoing cassava genetic improvement programs in Tanzania and germplasm conservation.