DSpace Repository :: Browsing by Author "Muturi, Phyllis W."

Browsing by Author "Muturi, Phyllis W."

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Additive main effects and multiplicative interaction analysis of genotype x environmental interaction among sweetpotato genotypes
(2009-04-08) Mwololo, J.K.; Muturi, Phyllis W.; Mburu, M.K.; Njeru, R.W.; Kiarie, N.; Munyua, J.K.; Ateka, E.M.; Muinga, R.W.; Kapinga, R.E.; Lemaga, B.
Sweetpotato is an important food, feed and cash crop in Eastern Africa. Highly stable and adaptable genotypes are important in sweetpotato productivity and evaluation across sites would form a basis for breeding varieties that are stable. Seventeen sweetpotato genotypes were evaluated for two seasons in three sites which have differentials in sweetpotato virus disease prevalence and climatic conditions in the coastal region of Kenya to determine their stability and adaptability in the region. The experimental design was randomized complete block design. Harvesting was done at four and half months after planting and tuber yield was determined. Data was analysed using the additive main effects and multiplicative interaction model (AMMI) to establish the genotype x environmental interactions (GEI). There was wide variation across the environments in the two seasons. Stability and adaptability was identified among sweetpotato genotypes. Varities Jonathan, Exshimba, SPK 004 and Kemb 10 were highly adapted across all the environments whereas Ejumula, Jewel, Jubilee, Bungoma, and sponge were stable. The highly adapted genotypes can be used as a basis for further improvement through breeding by crossing with the stable genotypes.
Agro-morphological characterization of horned melon (Cucumis metuliferus) accessions from selected agro-ecological zones in Kenya
(Australian Journal of crop science, 2020-09) Owino, Marline H.; Gichimu, Bernard M.; Muturi, Phyllis W.
Morphological characterization of genotypes is fundamental in providing information on their genetic status to guide on their conservation and improvement. The objective of this study was to determine agro-morphological diversity within horned melon in Kenya. The study was carried out in two seasons at the University of Embu in Kenya. The study characterized 19 horned melon accessions collected from different agro-ecological zones in Eastern, Central and Western regions in Kenya. The experiment was laid out in a randomized complete block design with three replications. Morphological characterization of the accessions was based on melon descriptors from International Plant Genetic Resources Institute (IPGRI) with slight modifications. Significant differences were observed in all the quantitative traits except the number of branches and main vine length. However, qualitative variations were only observed in fruit shape, rind colour and seed shape. Principle Component Analysis (PCA) showed that fruit weight, main vine length and days to maturity had the highest contribution to the observed diversity. Cluster analysis separated the accessions into seven groups with between classes diversity of 79.20% and within classes diversity of 20.80%. The diversity observed can be exploited by plant breeders for genetic improvement of the crop.
Characterization of the Volatile Components of Essential Oils of Selected Plants in Kenya
(Hindawi, 2020-12) Mugao, Lydia G.; Gichimu, Bernard M.; Muturi, Phyllis W.; Mukono, Simon T.
Essential oils are secondary metabolites that plants produce for protection from pests and predators, attraction of pollinators, and seed dispersal. )e oils are made up of a mixture of compounds that give a characteristic flavour and odour. Currently, essential oils are receiving great attention in research for their phytochemical and antimicrobial activities. However, there is scanty information on the chemical composition of many plants. )is study provides a detailed analysis of the chemical composition of essential oils of ginger, garlic, tick berry, and Mexican marigold in Kenya. )e essential oils were extracted by steam distillation and analysed by gas chromatography–mass spectrometry. )e study identified a total of 52 different chemical classes from the essential oils of the four different plants that were analysed. )eir percentage composition was also found to vary between the test plants. )e essential oils of Mexican marigold constituted the highest composition of the identified chemical classes at 71.2%, followed by ginger at 55.8%, while both tick berry and garlic oils constituted 53.8% of the total classes identified. Terpenes constituted the highest composition in the essential oils of all the four test plants. Other major chemical classes included esters, ketones, organosulfurs, alkanes, cycloalkanes, steroids, aromatic hydrocarbons, and alkanols. Some of these chemical compounds have been shown to have a huge utility potential in biopesticides, pharmaceutical, and food industries, and hence, their industrial extraction and purification from the essential oils of these plants are recommended.
Identification of new sorghum genotypes resistant to the African and spotted Stem borers
(2014) Muturi, Phyllis W.; Mgonja, M.; Rubaihayo, P.
Lepidopteran stemborers, mainly the African stemborer Busseola fusca Fuller and spotted stemborer Chilopartellus Swinhoe, are among the economically important pests of sorghum in Kenya. Identification of sources of resistance is valuable for the development of an integrated pest management strategy to minimize losses. This study evaluated 27 genotypes with artificial infestations (mostly for tolerance) in two different agroecological zones. Data on damage from leaf feeding, dead heart, exit holes, and stem tunnelling; plant height; days to 50% flowering; total grain yield; and hundred-grain mass were collected. Significant differences (P< 0.001) were observed in all the traits evaluated, except leaf damage, under infestation by C. partellus. Classification into different categories of resistance revealed genetic variation. Genotypes resistant/moderately resistant to both pests were as follows: ICSA 464>ICSB 464>ICSB 467>ICSA 472>ICSB 472>ICSA 473>ICSA 474>IESV 91131 DL>Macia. The relative contributions of the damage parameters to grain yield loss were partitioned into direct and indirect relationships by path coefficient analysis with grain yield as the resultant variable. The results revealed that damage from exit holes, dead heart, leaf feeding and stem tunnelling had a negative indirect effect on grain yield. The identified genotypes can be used to enhance resistance to both pests in susceptible cultivars that farmers prefer.
In Vitro Control ofPhytophthora infestans and Alternaria solani Using Crude Extracts and Essential Oils from Selected Plants
(Hindawi, 2020-07) Mugao, Lydia G.; Muturi, Phyllis W.; Gichimu, Bernard M.; Njoroge, Ezekiel K.
Tomato production is constrained by fungal diseases especially the early and late blight caused by Alternaria solani and Phytophthora infestans, respectively. Control of the two diseases is usually by use of synthetic fungicides which have a long residue effect and also contribute to environmental pollution. Innovative use of biocontrols may offer an eco-friendly and more sustainable solution. (is study tested the in vitro efficacy of crude extracts and essential oils of ginger, garlic, tick berry, and Mexican marigold in inhibition of radial growth of A. solani and P. infestans. Extraction of the crude extracts was done using distilled water, ethanol, and methanol solvents, while essential oils were extracted using the dry steam distillation method. (e extracts and essential oils were used to amend the growth media of the test pathogens before introducing the precultured pathogens. Sterile distilled water and synthetic fungicide, Ridomil Gold®, were used as positive and negative controls, respectively. Fungal growth inhibition was determined by measuring the radial growth of the test pathogens. Both the crude extracts and the essential oils portrayed some efficacy against the test pathogens. Garlic crude extracts were found to be the most effective, while ethanol was the most suitable extraction solvent. Essential oils were more effective in restricting the pathogen growth than crude extracts. Ginger and garlic oil was found to be as effective as the synthetic fungicide, and thus it was concluded that the two plants have strong antifungal properties with high potential of being utilized as biofungicides. However, effective utilization of these products in farmers’ fields may require industrial formulation to improve their efficiency
Influence of drought on interactions between Rhopalosiphum padi and ground dwelling predators – A mesocosm study
(Wiley, 2021-05) Njue, Martin; Muturi, Phyllis W.; Nyaga, Justine M.; Jonsson, Mattias
Climate change will lead to extreme droughts, but it is difficult to predict how this will affect crop pests. In particular, it is unclear how interactions between natural en- emies and pests will be influenced. In the field, bird cherry- oat aphids (Rhopalosiphum padi (L.)) have been observed to reside close to, or below the ground surface during dry conditions. We hypothesized that this will increase the niche overlap between R. padi and ground- dwelling predators such as carabid beetles and wolf spiders and that aphid numbers will therefore decline during dry conditions. A fully factorial mesocosm experiment was conducted testing the combined effects of drought and predator presence on aphid position and abundance on barley (Hordeum vulgare) plants. In support of our hypothesis, we found that (a) aphids moved below ground during dry conditions, (b) predators reduced aphid numbers, but only during dry conditions, and (c) predators reduced the proportion of aphids below ground in dry conditions. This increased predation effect during dry conditions was, however, compensated for by a corresponding increase in aphid performance on the plants and so the net effect of drought on aphid numbers ended up being neutral. Thus, pests can be affected by drought in complex ways via a combination top- down and bottom- up mechanisms. Predicting how pest populations will be affected by droughts in the future is thus a formidable research challenge.
New sources of resistance to spotted stem borer, Chilo partellus in sorghum
(2012) Muturi, Phyllis W.; Rubaihayo, P.; Mgonja, M.; Kyamanywa, S.; Kibuka, J.; Sharma, H.C.
The lepidopteran Chilo partellus Crambid, an introduced pest in East and southern Africa from Asia, is the most economically important stem borer species infesting cereals in Africa. Chilo partellus causes more than 40% yield loss in sorghum in East Africa. Cultural strategies, biological control using parasitoids, as well as pesticides are being employed, but are either ineffective or uneconomic for resource constrained farmers in cereal production. Thus host resistance remains the most economic viable strategy. Sorghum is an African crop and has thus co-evolved with several pests, inherently developing resistance to them as well as C. partellus. Moreover, C. partellus is exotic with limited sources of resistance in local sorghum. Sorghum from other ecologies with a long history of C. partellus infestation could thus provide additional and new sources of resistance. The objective of this study was to evaluate a panel of local and exotic sorghum genotypes for resistance to C. partellus. Seven genotypes from East Africa and twenty from India were evaluated at Kiboko, Kenya, for tolerance/resistance to C. partellus during long- and short-rainy seasons of 2010. Test plants were artificially infested with five stem borer neonates, and data were recorded on leaf feeding, deadhearts, stem tunneling and exit holes as well as agronomic parameters. Based on selection index generated, genotypes ICSA 472, ICSA 473, ICSV 700 and ICSA 464 were resistant owing to antibiosis and antixenosis mechanisms of resistance. These genotypes can be used in sorghum improvement to develop cultivars with high grain yield and resistance to C. partellus.
Novel source of sorghum tolerance to the African stem borer, Busseola fusca
(Academic Journals, 2012-08) Muturi, Phyllis W.; Rubaihayo, P.; Mgonja, M.; Kyamanywa, S.; Sharma, H.C.; Hash, C.T.
Sorghum (Sorghum bicolor) is an important cereal food crop in semi-arid tropics, but its productivity is curtailed mainly by insect pests and diseases. The African stem borer, Busseola fusca Fuller (Lepidopteran: Noctuidae), is among the most injurious pests of sorghum in sub-Saharan Africa and is responsible for >15% sorghum grain yield losses. Sorghum from India with records of stem borer invasion could provide supplementary and novel resources of tolerance to this pest. Utilization of tolerant varieties in combination with other methods of control is likely to offer a sustainable strategy for B. fusca management in sorghum production. The objective of this study was to evaluate several local and exotic sorghum genotypes for tolerance to B. fusca. Genotype Swarna from India which is known to be susceptible to Chilo partellus was used as a susceptible check. There is limited information regarding tolerant/resistant sorghum to B. fusca. Seven commercial cultivars and 20 introductions from India were evaluated for B. fusca tolerance at Kabete, in central province of Kenya, during long and short rainy seasons in 2010. Selection index were based on leaf damage, dead hearts, exit holes and stem tunneling. The following genotypes named ICSA 467, ICSA 473, MACIA and ICSB 464 were found to be the most tolerant to B. fusca. These tolerant genotypes, can be used as novel sources of tolerance, and could be introgressed into the local common varieties since they are well adapted to the local environment.
An overview of advances in bioinformatics and its application in functional genomics
(2010-04-28) Mwololo, J.K.; Munyua, J.K.; Muturi, Phyllis W.; Munyiri, S.W.
Bioinformatics is the scientific discipline that is concerned with the efficient management and useful interpretation of large scale biological information. Functional genomics aims at mapping DNA sequences and the components they encode for, to the function they perform. Initial efforts in bioinformatics were focused on the analysis of DNA sequence data. Presently, the scope and objectives of bioinformatics research and development have been broadened owing to the accelerating generation of data from various sources and for various cellular processes, the continuously evolving analytical technologies and the increasing computational capability. Bioinformatics offers an indispensable technology for function assignment and it has been used widely for gene annotation based on protein function predictions. However, as the sequence information is growing exponentially, the number of genes of unknown function is also growing, creating a challenge in the current computational approaches applied in bioinformatics. These limitations are being overcome through advances combining experimental and computational approaches, e.g. nanofabrication techniques. Despite the progress attained, analysis frameworks that could be used to analyze large data arising from signal transduction and biotransformation to provide quantitative predictions are inadequate. Trancriptome profiling is important because it provides information on the number of genes and their abundance in a tissue or given an induced condition e.g. diseased plants. Microarrays are hybridization experiments involving comparison of relative amounts of cellular mRNA from two tissue samples. Most of microarrays used in biological sciences can be divided into complementary DNA (cDNA) and oligonucleotide microarrays. The exploitation of hybridization in microarray analyses has sharply accelerated the search for defective genes of interest in both plants and animals. Microarrays provide the means to repeatedly measure the expression levels of a large number of genes at a time. Major limitations of this technology include decreased sensitivity of the arrays to the detection of genes with low expression levels and difficulties in data exchange due to the lack of standardization in platform fabrication, assay protocols and analysis methods.
Performance of sweet potato varieties across environments in Kenya
(2012-09) Mwololo, J.K.; Mburu, M.K.; Muturi, Phyllis W.
Sweetpotato is an important food, feed and cash crop in Eastern Africa but its adoption as a dual purpose crop has not been exploited. Varieties giving high tuber and vine yields would be ideal for small scale farmers who are the predominant producers. The objective of the study was to evaluate and identify farmer-preferred adapted sweetpotato varieties which are high yielding in relation to food and feed. Sweetpotato varieties were evaluated in three sites at the coast between May 06 and February 07, one in Kilifi (KARI-Mtwapa) and two on farm sites in Lukore and Mwaluvanga locations, Kwale district. The experimental trials were laid out as randomised complete block design (RCBD). Ground cover was determined. Sweetpotato virus disease (SPVD) incidence was monitored. The yield data was partitioned into marketable and non-marketable tubers, vine and tuber yield on weight basis. The yield of the disease tolerant varieties was stable in seasons and sites. Varieties with farmer and market desired traits such as high tuber yield and vine mass were identified. Dissemination of disease tolerant sweetpotato varieties coupled with building farmers capacity to maintain clean vines can sustain sweetpotato productivity.
A perspective on proteomics: current applications, challenges and potential uses
(Academic Journals, 2010-08) Muturi, Phyllis W.; Mwololo, J.K.; Munyiri, S.W.; Rubaihayo, P.; Munyua., J.K.; Mgonja, M.; Manyasa, E.; Kiarie, N.
Biological sciences are experiencing an ongoing information revolution. Proteome-wide functional classification using bioinformatics approaches is becoming an important method for revealing unknown protein functions. Most successful computational approaches for protein function prediction integrate multiple genomics and proteomics data sources to make inferences about the function of unknown proteins. Research into gene expression and proteomics enable scientists to decipher the functions of genes and their protein products, and to get a clearer picture of the complex regulatory networks that control fundamental biological processes. The global study of cellular proteins by proteomics may be able to provide the complete picture. Use of proteins to study gene function and genetic information is possibly the most reliable method but costly and labour intensive. Analysis of gene-expression patterns is no less powerful concept than proteomics when it comes to identification of the characteristics of signalling pathways or disease states. This review discusses current applications of proteomics, challenges and potential uses.
Staff Profile - Dr. Phyllis W. Muturi
(University of Embu, 2015-07) Muturi, Phyllis W.
Dr. Muturi holds a PhD in Plant Breeding and Biotechnology from Makerere University, Uganda, MSc. in Crop Protection and BSc. Agriculture from University of Nairobi, Kenya. She won scholarships for postgraduate training (MSc and PhD) from the Regional Universities Forum for Capacity Building in Agriculture (RUFORUM). In 2012, she was recognized by the African Women in Agricultural Research and Development Programme (AWARD) to be among the 70 impressively talented and motivated very young women researchers in Africa. In 2013, she was awarded a two-year fellowship by AWARD to strengthen her leadership and science skills. AWARD is a professional development program that strengthens the research and leadership skills of African women in agricultural science, empowering them to contribute more effectively to poverty alleviation and food security in sub-Saharan Africa. She has over five years practical experience in dry lands research in collaboration with International Crops Research Institute for Semi Arid Tropics (ICRISAT). Team player and networked with scientists from public and private sectors. She has worked with rural communities and participated in farmers exchange programs in Eastern Africa. She has presented her research findings in conference and published her work in international peer reviewed journals. She is a mentor and participates in community development projects/programmes.
Utilization of proteins and nucleic acids in the study of gene function: a comparative review
(2010) Mwololo, J.K.; Karaya, H.G.; Munyua, J.K.; Muturi, Phyllis W.; Munyiri, S.W.
Proteomics is one of the fastest growing areas in areas of research, largely because the global-scale analysis of proteins is expected to yield more direct understanding of function and regulation than analysis of genes. Protein structure characterizes its function and a protein sequence that relates to a known structure forms a basis for identifying gene function. Proteins are encoded by the genome (genes), and the set of proteins encoded by the genome, including the added variation of post-translational modification, constitute the proteome. The proteins are involved in nearly all metabolic activities, hence are part of the tools that make living machines work. The proteome is neither as uniform nor as static as the genome. However challenges encountered in identifying the biochemical and cellular functions of the many gene products which are currently not yet characterized has necessitated the use of the proteome. Gel electrophoresis techniques allow the separation of cellular proteins on a polymer according to their molecular weight and isoelectric point. The development of automated methods for the annotation of predicted gene products (proteins) with functional categories is becoming increasingly important. Compared to the study of the genetic code, proteomics may allow greater understanding of the complexity of life and the process of evolution due to the large number of proteins that can be produced by an individual organism. The measurable changes in protein profiles are also being used in diagnosis of emerging diseases. A major challenge to proteomics is that proteins are dynamic and interacting molecules, and their variability can complicate detailed studies on gene function. Nevertheless, measuring the intermediate step between genes and proteins i.e. the messenger RNA (mRNA) or the transcriptome bridges the gap between the genetic code and the functional molecules that regulate cell functions. This review examines protein amenability to prediction of gene function and the potential of proteomics in biological research.

Browsing by Author "Muturi, Phyllis W."

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