Johnstone O Neondo - Academia.edu (original) (raw)

Papers by Johnstone O Neondo

Frontiers in Genetics, 2022

Doum palm (Hyphaene compressa) is a perennial economic plant primarily growing in Kenya’s Arid an... more 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 novo-based 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 ancest...

Additional file 4: Table S2. Means of quantitative variables of Crotalaria accessions from Kenya.

A Thesis Submitted in Fulfillment of the Requirements for the Award of Doctor of Philosophy Degre... more A Thesis Submitted in Fulfillment of the Requirements for the Award of Doctor of Philosophy Degree in Biotechnology in the Jomo Kenyatta University of Agriculture and Technology 2017

Additional file 6: Figure S1. Sample clustering of 83 Crotalaria accessions from Kenya based on t... more Additional file 6: Figure S1. Sample clustering of 83 Crotalaria accessions from Kenya based on their agro-ecological regions using both quantitative and qualitative characters.

Additional file 2: Table S3. Summary information on the interviewed Crotalaria farmers in Kenya.

Additional file 5: Table S5. Cluster wise means and range values for the different traits used to... more Additional file 5: Table S5. Cluster wise means and range values for the different traits used to study phenomic diversity of Crotalaria species in Kenya.

In vitro regeneration of open pollinated varieties (OPVs) Kakamega Striga Tolerant Population 94 ... more In vitro regeneration of open pollinated varieties (OPVs) Kakamega Striga Tolerant Population 94 (KSTP’94) and ‘Namba Nane’ alongside a tropical inbred line (CML144) was evaluated using immature zygotic embryos as explants. Four callus induction media (CIM) regimes; Murashige and Skoog (MS), Linsmaier and Skoog (LS), Chu (N6) and N6*(N6 medium fortified with 0.35 gL-1 L-proline and 0.8 mgL-1 AgNO3) were evaluated for their potential to induce callus in the three genotypes. All the media were supplemented with sucrose and five levels of 2, 4-Dichlorophenoxyacetic acid (2, 4-D) (0.5, 1.0, 1.5, 2.0 and 2.5 mgL-1). Resulting calli were matured on MS and N6 basal media supplemented with 60 g/L sucrose and similar concentration levels (0.5, 1.0, 1.5, 2.0 and 2.5 mgL-1) of 2, 4-D while the subsequent embryogenic calli were regenerated on hormone-free media. Transformability of these varieties was assessed via histochemical analysis of β-glucuronidase (GUS) reporter gene following Agrobacte...

Scientifica, 2020

Hyphaene compressa is an economically important palm in Africa. Despite its significant role in t... more 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. There was variability in H. compressa morphological traits, particularly...

International Journal of Vegetable Science, 2020

Ethnobotany Research and Applications, 2020

Background: Peasant agroecosystems in Kenya are considered to be a continuum of integrated tradit... more 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.

International Journal of Microbiology, 2020

The emergence and persistence of antibiotic resistance remain formidable health challenges. This ... more The emergence and persistence of antibiotic resistance remain formidable health challenges. This study aimed at detecting and profiling antibiotic resistance of bacterial contaminants in vended food and the environment. Seventy antibiotic-resistant bacterial isolates were isolated from fried fish, African sausages, roasted meat, smokies, samosa, chips (potato fries), vegetable salads, and soil samples collected from Embu Town and Kangaru Market in Embu County, Kenya. The antibiotic susceptibility test, morphological and biochemical characterization, antibiosis assay, polymerase chain reaction-based detection of antibiotic resistance genes, and sequencing of the 16S rRNA gene were done. Analysis of variance on all measured data was done, and Tukey’s honest test was used to compare and separate mean diameters of zones inhibition. Resistance of bacterial isolates to antibiotics was chloramphenicol (90%), cefotaxime (84.29%), nalidixic acid (81.43%), tetracycline (77.14%), amoxicillin (...

International Journal of Agronomy, 2020

Slender leaf (Crotalaria spp) is among the indigenous and underutilized vegetables in Kenya whose... more Slender leaf (Crotalaria spp) is among the indigenous and underutilized vegetables in Kenya whose production is limited to the Western and Coastal regions of the country. For a long time, this crop has been neglected in terms of research and genetic improvement. There is therefore scanty information on its morphological diversity and agronomic performance, hence the need for this study. Field experiments were carried out for two seasons in October to December 2018 and March to May 2019. The experiments were laid out in Randomized Complete Block Design with 29 accessions and replicated three times. Both qualitative and quantitative data were recorded from the accessions based on the Crotalaria descriptors. Quantitative data were subjected to analysis of variance using XLSTAT Version 2019, and accession means were separated using Student’s Newman Keuls test at 95% level of confidence. Both qualitative and quantitative data were subjected to multivariate cluster analysis, and a dendrog...

The cellular-growth curves for distinct cell lines (tumor and non-tumor) were established, evalua... more The cellular-growth curves for distinct cell lines (tumor and non-tumor) were established, evaluating the population of doubling time (DT) and maximum growth rate (µ max). These curves define the growth characteristics for each cell line; they allow determination of the best time range for evaluating the effects of some biological compounds. Subsequently, the biological activities of three ethanolic extracts of Phoradendron californicum were evaluated in these cells lines; two extracts were of Prosopis laevigata (Mesquite tree) from two distinct geographic zones, and the other one was of Quercus ilex (Encino/Oak tree). We also evaluated the cytotoxic activity and nitric oxide (NO) scavenging ability of these extracts. The results showed the RAW 264.7 cell-line had the highest growth rate in all experiments. For the rest of cell-lines, we found µ max in the following order: L929 > A549  ARPE-19 ≥ 22Rv1; while the DT was in the order: RAW 264.7 > A549 ≥ L929  ARPE-19 > 22Rv1. With respect to the anti-proliferative activity of the P. californicum ethanolic extracts, we observed that the most sensitive cell line was RAW 264.7 (with all three extracts), and the least sensitive was the ARPE-19 cell line; the first one was the fastest growing and the second was the one of the slowest. The antioxidative studies by NO scavenging were evaluated in RAW 264.7 cell-line, the best extracts were the ethanolic extracts of P. californicum from P. laevigata and were geographic zone no-dependent for these biological activities.

BioControl, 2017

Striga hermonthica is a hemiparasitic weed that causes huge grain yield losses to small-scale far... more Striga hermonthica is a hemiparasitic weed that causes huge grain yield losses to small-scale farmers in Africa. Effective biocontrol agents against S. hermonthica can sustainably mitigate these losses. This study characterized the biocontrol potential of culturable fungal and bacterial isolates from S. hermonthica suppressive soils of western Kenya. These isolates were screened for their ability to produce antibiotic compounds and extra cellular enzymes and also their ability to cause S. hermonthica seed decay. Genomic DNA of the selected bacterial and fungal isolates was extracted and partial characterization of 16S rRNA and 18S rRNA genes performed respectively. Analysis show that antibiosis and enzymatic properties of potential biocontrol isolates correlated positively. Isolate KY041696 recorded high antibiosis, enzymatic and seed decay values. This study also revealed that bioactive bacterial isolates belonged to Bacillus, Streptomyces and Rhizobium genera. In this study, no fungal isolate caused S. hermonthica seed decay. This study therefore provides baseline information on the potential biocontrol microbes against S. hermonthica in Western Kenya that could be exploited further in the management of the weed.

Phytotherapy Research, 2017

Additional file 3: Table S4. Correlation of cultivation aspects of edible Crotalaria species base... more Additional file 3: Table S4. Correlation of cultivation aspects of edible Crotalaria species based on 37 sampled farmers in Kenya.

Additional file 1: Table S1. Summary information of the different samples used to study phenomic ... more Additional file 1: Table S1. Summary information of the different samples used to study phenomic diversity of Crotalaria species in Kenya.

International Journal for Biotechnology and Molecular Biology Research, 2011

Tissue culture is prone to high costs of production arising from losses incurred from fungal cont... more Tissue culture is prone to high costs of production arising from losses incurred from fungal contamination. The aim of the study was to characterise fungal contaminants and elucidate the exhibited mode of resistance to most preferred sterilants. Twenty nine fungal samples were collected at the different stages of tissue culture growth, using purposive sampling technique. Morphology results were confirmed by molecular characterization using fungal 18S rRNA sequences. Biochemical and antibiosis tests, identification of genes for capsulation and ATP binding Cassete (ABC) transporters, were performed to show the relationship between the fungi and sterilants resistance. Amylases and proteases were highly expressed by all isolates while xylanases and lipases were moderately expressed and esterases were lowly expressed. Only fourteen isolates had antagonistic activity for Candida albicans while nine of them had antagonistic activity for Pseudomonas aeruginosa. Three isolates were both ant...

CABI Agriculture and Bioscience

Background Diversification of global food systems through exploration of traditional varieties an... more Background Diversification of global food systems through exploration of traditional varieties and wild edible plant species is a focal mitigation strategy for food security worldwide. The present study determined the phenomic diversity of locally available, affordable and climate-resilient cultivated and wild Crotalaria species for breeding purposes. Methods Seed samples were collected from different administrative counties in Kenya spanning different climatic zones. Other seeds were provided by the Genetic Resources Research Institute of Kenya. A randomized complete block design with three replications was used for agro-morphological evaluation of the 83 accessions used in this study. Data on quantitative and qualitative traits was collected. Cluster analysis on R and R-studio was used to generate a dendrogram by the Euclidian genetic distance and dissimilarity indices while the non-metric multidimensional scaling (NMDS) method was used to determine the spatial interrelationship b...