Browsing by Author "Mweu, Cecilia"

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    Drought Response in Selected Tropical Inbred Maize Lines and Relative Expression of PARP2 Gene under Limited Water Conditions
    (Science Publishing Group, 2018-04) Muli, Joshua K.; Budambula, Nancy; Mweu, Cecilia; Anami, Sylvester E.
    Drought is the leading single factor that limits maize production thus inhibiting the crops genetic potential. In response to drought, maize and other plants synthesize Poly ADP-Ribose (PAR) protein. This process is controlled by the Poly ADP-Ribose Polymerase (PARP) genes and consumes cellular energy, leading to plant death. This study evaluated four tropical inbred maize (Zea mays L.) lines; CML 216, CML 144, A04 and E04 for their response to growth limiting water stress and their relative expression of PARP2 gene under drought and non-drought conditions. The leaf lengths and growth rates of the fourth leaf were monitored for 21days post emergence while fresh and dry weights of drought stressed and non-stressed seedlings were recorded a month after emergence of the fourth leaf. The relative expression of PARP2 gene was determined using rtPCR after isolating RNA from drought stressed and non-stressed maize seedlings. There was no significant difference in the mature lengths of the fourth leaf in the four genotypes when the maize seedlings were not subjected to drought and when subjected to severe drought stress. However, subjecting maize seedlings to mild drought resulted in a significant difference in the mature leaf lengths based on the different genotypes (P= 0.0066). The growth rate of maize seedlings based on the fourth leaf was observed to be affected by drought, with a higher mean growth rate (1.74 cm day-1) registered in seedlings which were not subjected to drought and those subjected to moderate drought (1.78 cm day-1). A slower growth rate (1.37 cm day-1) was observed in seedlings subjected to severe drought stress. Fresh and dry weights of maize seedlings were also observed to be significantly different based on the level of drought exerted (P = < 0.0001) and the genotype (P = < 0.0001). The expression of PARP2 gene was found to be directly proporti
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    Genetic Diversity and Population Structure of Doum Palm (Hyphaene compressa) Using Genotyping by Sequencing
    (Frontiers, 2022-02) Omire, Agnes; Neondo, Johnstone; Budambula, Nancy; Wangai, Laura; Ogada, Stephen; Mweu, Cecilia
    Doum palm (Hyphaene compressa) is a perennial economic plant primarily growing in Kenya’s Arid and Semi-Arid Lands (ASALs). It is heavily relied upon for food, animal feed, construction materials and medicine, making it an ideal plant for resource sustainability. However, the limited information on its genetic resources has hindered its breeding and conservation studies. This study used the genotyping by sequencing approach to identify Single Nucleotide Polymorphisms. These SNPs were further used to assess the genetic diversity and population structure of 96 H. compressa accessions from Coastal, Northern and Eastern ASAL regions of Kenya using two approaches; reference-based and de novobased assemblies. STRUCTURE analysis grouped the sampled accessions into two genetic clusters (Cluster 1 and Cluster 2). Cluster 1 included accessions from the Northern region, whereas Cluster 2 included all accessions from Eastern and Coastal regions. Accessions from Kwale (Coastal) had mixed ancestry from both Cluster 1 and Cluster 2. These STRUCTURE findings were further supported by principal components analysis, discriminant analysis of principal components and phylogenetic analysis. Analysis of molecular variance indicated greater genetic variation within populations (92.7%) than among populations (7.3%). An overall FST of 0.074 was observed, signifying moderate genetic differentiation among populations. The results of this study will provide information useful in breeding, marker-assisted selection and conservation management of H. compressa.
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    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 and feed either directly or indirectly. Maize in Africa is affected by many stresses, both biotic and abiotic which significantly reduce yields and eventually lead to poor production. Due to the high demand for maize in the region, different improvement strategies have been employed in an effort to improve production. These include conventional breeding, molecular breeding, high throughput phenotyping techniques and remote sensing-based techniques. Conventional breeding techniques such as open pollination have been used to develop drought avoiding maize varieties like the Kito open pollinated variety (OPV) of Tanzania and Guto OPV of Ethiopia. A combination of conventional breeding and molecular biology techniques has led to improved breeding strategies like the Marker Assisted Back Crossing (MABC) and Marker Assisted Recurrent Selection (MARS). These techniques have been used to improve drought tolerance in existing inbred maize lines like the CML 247 and CML 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 shown increased tolerance to drought stress. Although there is substantial progress towards developing drought tolerant maize, many African farmers are yet to benefit from this technology. This is due to lack of an enabling policy framework as well as a limited financial investment in biotechnology research.
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    Hyphaene compressa, an important palm in the arid and semi-arid regions of Kenya
    (2020-06) Omire, Agnes; Neondo, Johnstone O.; Budambula, Nancy; Gituru, Robert; Mweu, Cecilia
    Background: Peasant agroecosystems in Kenya are considered to be a continuum of integrated traditional farming systems and natural ecosystem conservancy programs. Hyphaene compressa (doum palm) exists in arid and semi-arid lands (ASAL) of Kenya. While research in these areas is focusing on new plants to be brought to the areas, there is no focus on doum palm, which is already adapted to these areas. Scanty ethnobotanical knowledge exists in the form of unpublished material. The study aimed to determine domestication status, management practices, important use categories, plant part value, biotic and abiotic stresses of H. compressa. Methods: Four sampling sites in the ASAL of Kenya were selected. Tharaka Nithi, Kwale, Tana River and Turkana. Responses of 79 informants were analyzed to establish doum palm domestication profile, uses, biotic and abiotic stresses affecting its growth. Results: The domestication status varied across the sampled areas, with most regions showing no willingness to domesticate the plant. The study revealed that doum palm has fourteen uses with food (fruit) use, and prevention of soil erosion (roots) recording the highest and the least fidelity level scores, respectively, in the sampled areas. The most observed biotic stress was human interference and pest infestation, while the observed abiotic stress was drought and salinity. Conclusion:The most important doum palm use is food. Due to the high usage and poor domestication, doum palm could be losing its gene pool and hence genetic diversity studies are important for its conservation.
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    Phenotypic Diversity of Doum Palm (Hyphaene compressa), a Semi-Domesticated Palm in the Arid and Semi-Arid Regions of Kenya
    (Hindawi, 2020-12-29) Budambula, Nancy L. M.; Neondo, Johnstone; Gituru, Robert; Mweu, Cecilia; Omire, Agnes
    Hyphaene compressa is an economically important palm in Africa. Despite its significant role in the livelihoods of rural communities, the diversity of doum palm is poorly documented and studied. In addition, it has no model descriptor that can aid such studies. Ninety H. compressa accessions collected from Northern, Eastern, and Coastal regions of Kenya were examined to determine the morphological variability of the vegetative and fruit traits of H. compressa and to identify its morphotypes for improvement. A total of 19 morphological characters including seven quantitative and 12 qualitative traits of fruit and vegetative traits were selected. Linear mixed-effects models, principal component analysis, and linear discriminant analyses were used to assess the variation in the morphological traits of doum palm based on the regions. Hierarchical clustering was performed to identify the morphotypes of H. compressa. )ere was variability in H. compressa morphological traits, particularly at the Kenyan Coast. All seven quantitative traits were able to effectively discriminate doum palm phenotypically (p ≤ 0.001). )e 90 accessions clustered into five morphotypes designated as 1, 2, 3, 4, and 5. Morphotype 4 was specific only to the Coastal region. Morphotype 5 had the tallest trees with the biggest fruits and included palms from Eastern and Coastal regions making it the best morphotype for fruit traits. )is study will inform the domestication, improvement, and conservation of H. compressa by selecting elite accessions.
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    Yeast Extract Peptone Based Co-cultivation Media Promotes Transient GUS Expression in Tropical Maize Genotypes
    (2017) Muli, Joshua K.; Mweu, Cecilia; Budambula, Nancy; Anami, Sylvester E.
    Background and Objective: Tropical maize is the most cultivated crop in sub-Saharan Africa and is a staple food to over 220 million people. This study, evaluated the competence of four tropical maize (Zea mays L.) inbred lines to callus induction and regeneration through somatic embryogenesis when co-cultivated on yeast extract peptone medium (YEP). Materials and Methods: Transient GUS assay was used to evaluate the competence of the genotypes to Agrobacterium-mediated transformation using YEP as co-cultivation media or when YEP was supplemented with 2,4-D (YEP+2,4-D), cysteine (YEP+CYS), proline (YEP+PRO) or in combination (YEP+ALL). Data on all parameters were analyzed using multivariate ANOVA and SAS. Results: Co-cultivation media based on YEP alone did not impact callus induction and immature embryos exhibited preconscious germination. When YEP was supplemented with 2,4-D at concentrations 1.5 and 3 mg LG1 2,4-D, the formation of embryogenic calli was induced and regeneration initiated. Immature embryos had high transient GUS expression when co-cultivated with Agrobacterium on YEP, YEP+PRO and YEP+ALL media than when co-cultivated on MS media, suggesting that YEP promotes Agrobacterium-mediated integration of transgenes in tropical maize. Agrobacterium tumefaciens at a concentration of 0.07 (OD660) gave the highest transient GUS expression (20.90%) while concentrations of 0.8 and 0.2 resulted in low transient GUS expression (9.17 and 12.22%, respectively). Conclusion: The integration of YEP media in the Agrobacterium-mediated transformation protocols is likely to contribute in the development of a more efficient Agrobacterium-mediated transformation system for tropical maize genotypes.