Establishment of an effective in vitro regeneration protocol for quality protein maize in Ghana

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NOVEMBER, 2016
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This study was aimed at establishing a consistent in vitro regeneration system for Quality Protein Maize (QPM) using mature embryos and root explants using two QPM genotypes from Ghana ‘Obatanpa GH’ and ‘Etubi’. The effect of MS and N6 basal media supplemented with 2,4-D, 6-BA and CPPU on callus and embryogenic callus induction as well as plant regeneration were investigated. For primary callus induction, 4mg/L 2,4-D gave the highest frequency of 70.8% to 91.7% from mature embryo on both MS and N6 while in root explant, 3mg/L 2,4-D induced maximum frequency of 50.0% to 68.8% on both MS and N6. Increasing 2,4-D concentration from 0mg/L to 4mg/L on mature embryo and 0mg/L to 3mg/L on root explant resulted in increase in frequency of callus induction, respectively. Primary calli varied from white to creamy and opaque with compact or friable texture. For embryogenic callus induction using matured embryo, a combination of 1.0mg/L 2,4-D and 0.2mg/L 6-BA was required to achieve highest frequency of 62.5% to 91.7% whereas 2mg/L 2,4-D and 0.4μM CPPU produced maximum frequency of 62.5% to 70.8% whiles embryogenic calli development from matured embryo was high and dependent on concentration of the growth regulators, development of embryogenic calli from root explants was low and inconsistent. A low and inconsistent frequency of embryogenic callus in root explant was obtained. Either 1mg/L or 2mg/L 2,4-D in combination with 0.2mg/L 6-BA produced 16.7% to 33.3% whereas at 3mg/L 2,4-D with 4 μM CPPU gave 29.1% to 37.5%. For shoot formation, 1mg/L 6-BA with 3mg/L IAA or 1mg/L 6-BA with 1.5mg/L IAA gave highest frequency of 53.3% to 73.3% and 40.0% to 66.7%, respectively, on mature embryo-derived embryogenic calli. Root-derived embryogenic calli produced lower shoot regeneration frequency of 40.0% to 46.7% at 2mg/L 6-BA and 0.5mg/L IAA. For root development, 0.4mg/L 2,4-D with 2mg/L NAA gave highest frequency of 33.3% to 58.3% from mature embryo-derived embryogenic calli. Highest root frequency of 25.0% to 62.5% from root-derived embryogenic calli were achieved at 0.2mg/L 2,4-D with 1mg/L NAA. Mature embryo explants developed comparatively higher plantlets than root explants. The two genotypes used as well as the basal media MS and N6 were not different with respect to primary callus induction, embryogenic callus induction, shoot and root regeneration.
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A thesis submitted to the Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements of Master of Science degree in Biotechnology,
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