Browsing by Author "Imbo, Mary C."

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  • Publication
    Publication
    Genetic Improvement of African Maize towards Drought Tolerance
    (IISTE, 2016) Budambula, Nancy; Muli, Jushua K.; Mweu, Cecilia; Imbo, Mary C.; Anami, Sylvester E.
    Africa supports a population of over 1 billion people with over half of them depending on maize for food andfeed either directly or indirectly. Maize in Africa is affected by many stresses, both biotic and abiotic whichsignificantly reduce yields and eventually lead to poor production. Due to the high demand for maize in theregion, different improvement strategies have been employed in an effort to improve production. These includeconventional breeding, molecular breeding, high throughput phenotyping techniques and remote sensing-basedtechniques. Conventional breeding techniques such as open pollination have been used to develop droughtavoiding maize varieties like the Kito open pollinated variety (OPV) of Tanzania and Guto OPV of Ethiopia. Acombination of conventional breeding and molecular biology techniques has led to improved breeding strategieslike the Marker Assisted Back Crossing (MABC) and Marker Assisted Recurrent Selection (MARS). Thesetechniques have been used to improve drought tolerance in existing inbred maize lines like the CML 247 andCML 176. Through genetic engineering, different genes including C4-PEPC, NPK1, betA, ZmNF-YB2, cspB,ZmPLC1 and TsVP have been cloned in maize. Transgenic maize crops expressing these genes have shownincreased tolerance to drought stress. Although there is substantial progress towards developing drought tolerantmaize, many African farmers are yet to benefit from this technology. This is due to lack of an enabling policyframework as well as a limited financial investment in biotechnology research.
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    Publication
    Genetic Improvement of African Maize towards Drought Tolerance: A Review
    (IISTE, 2016) Budambula, Nancy; Muli, Jushua K.; Mweu, Cecilia; Imbo, Mary C.; Anami, Sylvester E.
    Africa supports a population of over 1 billion people with over half of them depending on maize for food andfeed either directly or indirectly. Maize in Africa is affected by many stresses, both biotic and abiotic whichsignificantly reduce yields and eventually lead to poor production. Due to the high demand for maize in theregion, different improvement strategies have been employed in an effort to improve production. These includeconventional breeding, molecular breeding, high throughput phenotyping techniques and remote sensing-basedtechniques. Conventional breeding techniques such as open pollination have been used to develop droughtavoiding maize varieties like the Kito open pollinated variety (OPV) of Tanzania and Guto OPV of Ethiopia. Acombination of conventional breeding and molecular biology techniques has led to improved breeding strategieslike the Marker Assisted Back Crossing (MABC) and Marker Assisted Recurrent Selection (MARS). Thesetechniques have been used to improve drought tolerance in existing inbred maize lines like the CML 247 andCML 176. Through genetic engineering, different genes including C4-PEPC, NPK1, betA, ZmNF-YB2, cspB,ZmPLC1 and TsVP have been cloned in maize. Transgenic maize crops expressing these genes have shownincreased tolerance to drought stress. Although there is substantial progress towards developing drought tolerantmaize, many African farmers are yet to benefit from this technology. This is due to lack of an enabling policyframework as well as a limited financial investment in biotechnology research.
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    Publication
    Genetic Transformation of Sweet Potato for Improved Tolerance to Stress: A Review
    (IISTE, 2016-10) Imbo, Mary C.; Budambula, Nancy; Mweu, Cecilia M.; Muli, Joshua K.; Anami, Sylvester E.
    The sweet potato (Ipomoea batatas Lam) is a major staple food in many parts of the world. Sweet potato leavesand tubers are consumed as food and livestock feed. Biotic and abiotic stresses affect yield leading to a reductionin production. This review analyzes factors limiting sweet potato production and the progress made towardsstress tolerance using genetic transformation. Genetic transformation could enhance yield, nutritional value andtolerance to stress. Transgenic sweet potatoes tolerant to biotic and abiotic stress, improved nutritional value andhigher yields have been developed. Sweet potato expressing the endotoxin cry8Db, cry7A1 and cry3Ca genesshowed lower sweet potato weevil infestation than non-transformed lines. Transgenic cultivar ‘Xushu18’expressing the oryzacystatin-1 (OC1) gene showed enhanced resistance to sweet potato stem nematodes. Sweetpotato line ‘Chikei 682-11’ expressing the coat protein (CP) exhibited resistance to the sweet potato featherymottle virus (SPFMV). Transgenics expressing the rice cysteine inhibitor gene oryzacystatin-1 (OC1) alsoexhibited resistance to the SPFMV. Transgenic cultivar ‘Kokei’ expressing the spermidine synthetase geneFSPD1 had higher levels of spermine in the leaves and roots, and displayed enhanced tolerance to drought andsalt stress. ‘Shangshu’ variety expressing the IbMas has shown enhanced tolerance to salt stress. Transgenic‘Lixixiang’ expressing IbMIPSI showed an up-regulation of metabolites involved in stress response to drought,salinity and nematode infestation. Transgenic ‘Yulmi’ sweet potato transformed with copper/zinc superoxidedismutase (CuZnSOD) gene showed an enhanced tolerance to methyl viologen induced oxidative and chillingstress. Similarly, transformation of cultivar ‘Sushu-2’ with betaine aldehyde dehydrogenase (BADH) generesulted in transgenics tolerant to salt, chilling and oxidative stress. Sweet potato varieties ‘Kokei14’ and ‘Yulmi’transformed with the bar gene were shown to be tolerant to application of the herbicide Basta. The developmentof stress tolerant varieties will immensely increase the area under sweet potato production and eventuallypromote the adoption of sweet potato as a commercial crop. Sweet potato research and breeding for stresstolerance still faces technical and socio-political hurdles. Despite these challenges, genetic transformationremains a viable method with immense potential for the improvement of sweet potato.