Regenerability and transformability of selected farmer preffered kenyan cassa va (manihot esculenta crantz) ecotypes
Marigi, Emma, N.
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Cassava (Manihot esculenta Crantz), a member of Euphorbiaceae is one of the most important food crops in Sub Saharan Africa. The roots are the primary part consumed and store abundant amount of starch. Cassava can be used for production of bioethanol for fuel, as animal feed and as raw material for starch industry. Its ability to grow on poor soils and resistance to pests and herbivores due to presence of cyanogens makes it an ideal crop for subsistence farmers. Conventional breeding programs in cassava have been successful in introduction of improved cultivars but a high degree of heterozygosity, irregular flowering in some cultivars and variable germination rates have hampered its progressive breeding. Cassava is clonally propagated making it amenable for improvement through genetic engineering. Most African cultivars have proven to be recalcitrant to the regeneration and transformation procedures available. This study therefore seeks to optimize regeneration and transformation protocols of selected Kenyan cassava ecotypes namely Karembo, Tajirika, Kibanda meno-mkubwa and Ex-Mariakani. Various explants will be collected from parental cultures established at the plant transformation laboratory, Kenyatta University. Regenerability will be tested through variation of auxins (2, 4-0 and picloram) and cytokinins (o-beuzylaruinopurine, a-naphthalene acetic acid and gibberellic acid). A construct carrying the uidA and GUS gene will be transformed into regenerable cassava ecotypes using Agrobacterium tumefaciens strain EHA 10 I under Kanamycin selecti~n. GUS assays will be conducted followed by molecular analysis via PCR to test for presence of the transgene. Qualitative data including photos of different stages of regeneration as well as GUS stains will be recorded. Multivariate analysis of variance will be performed using SAS to determine statistical significance in regeneration and transformation frequencies and efficiencies among the ecotypes. The results from the study will contribute towards genetic improvement of recalcitrant Kenyan cassava ecotypes against various production constraints