Browsing by Author "Onyilo, Francis"

Now showing 1 - 9 of 9
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    Agricultural Cooperative marketing and credit policy reform in Uganda: An opportunity for poverty reduction
    (African Journal of Food, Agriculture, Nutrition and Development, 2019) Onyilo, Francis; Adong, Annet
    Academics and development practitioners increasingly view cooperatives as the cornerstone for agricultural transformation and poverty reduction in sub-Saharan Africa. Cooperatives play a crucial role in promoting bulk storage and sale by smallholder farmers, which can play a major role in poverty reduction for farmers otherwise unable to commercialize. Despite the significant role of cooperatives, the reforms associated with economic liberalisation have caused many cooperatives in the region to fail. While efforts were made in Uganda to ameliorate this situation through the passing of the National Co-operative Policy (NCP), this has done little to enhance the survival of these cooperatives. In this opinion paper, we identify challenges faced by cooperatives that negatively impact performance and survival, such political interference, lack of administrative support, human resource constraints, inadequate knowledge of the operations by members and poor governance. This paper recommends stronger linkages between the Ministry of Trade, Industry and Cooperatives and the Ministry of Agriculture Animal Industry and Fisheries (MAAIF). Integrating cooperatives into the decentralisation framework and formalising existing village savings and loan association groups into formal cooperatives. Most importantly, the government needs to take on a more proactive approach toward cooperative development, as seen in some countries such as South Africa and Rwanda.
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    Agrobacterium tumefaciens-mediated transformation of pseudocercospora fijiensis to determine the role of PfHog1 in osmotic stress regulation and virulence modulation
    (Frontiers in Microbiology, 2017) Onyilo, Francis; Tusiime, Geoffrey; Chen, Li-Hung; Falk, Bryce; Stergiopoulos, Ioannis; Tripathi, N. Jaindra; Tushemereirwe, Wilberforce; Kubiriba, Jerome; Changa, Charles; Tripathi, Leena
    Black Sigatoka disease, caused by Pseudocercospora fijiensis is a serious constraint to banana production worldwide. The disease continues to spread in new ecological niches and there is an urgent need to develop strategies for its control. The high osmolarity glycerol (HOG) pathway in Saccharomyces cerevisiae is well known to respond to changes in external osmolarity. HOG pathway activation leads to phosphorylation, activation and nuclear transduction of the HOG1 mitogen-activated protein kinases (MAPKs). The activated HOG1 triggers several responses to osmotic stress, including up or down regulation of different genes, regulation of protein translation, adjustments to cell cycle progression and synthesis of osmolyte glycerol. This study investigated the role of the MAPK-encoding PfHog1 gene on osmotic stress adaptation and virulence of P. fijiensis. RNA interference-mediated gene silencing of PfHog1 significantly suppressed growth of P. fijiensis on potato dextrose agar media supplemented with 1 M NaCl, indicating that PfHog1 regulates osmotic stress. In addition, virulence of the PfHog1-silenced mutants of P. fijiensis on banana was significantly reduced, as observed from the low rates of necrosis and disease development on the infected leaves. Staining with lacto phenol cotton blue further confirmed the impaired mycelial growth of the PfHog1 in the infected leaf tissues, which was further confirmed with quantification of the fungal biomass using absolute- quantitative PCR. Collectively, these findings demonstrate that PfHog1 plays a critical role in osmotic stress regulation and virulence of P. fijiensis on its host banana. Thus, PfHog1 could be an interesting target for the control of black Sigatoka disease in banana.
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    First report of banana bunchy top disease caused by Banana bunchy top virus in Uganda
    (Wiley, 2021-11-16) Ocimati, Walter; Tazuba, A.F.; Tushemereirwe, Wilberforce Kateera; Tugume, Joab; Omondi, Bonaventure Aman; Acema, Dan; Were, E.; Onyilo, Francis; Ssekamate, A.M.; Namanya, P.; Kubiriba, J.; Erima, R.; Okurut, A.W.; Kutunga, D.; Blomme, G.
    In August 2020, banana plants with characteristic symptoms of banana bunchy top disease (BBTD) caused by the Banana bunchy top virus (BBTV) were observed on two different banana (Musa sp.) mats in backyard gardens in Arua City (GPS coordinates: 2o59’36’’N 30o54’40’’E), West Nile region of Uganda. The plants were severely stunted with short, narrow leaves, chlorotic leaf margins and dark green streaks on petioles and midribs. The affected plants had a rosette-like or bunchy and choked appearance (Figures 1–2). A PCR using specific primers that amplify a 240 bp conserved domain of the BBTV DNA-mRep segment (Mansoor et al., 2005) confirmed the presence of BBTV in leaf, pseudostem and corm samples of the two symptomatic plants. The PCR product from one of the samples was purified and reverse sequenced (GenBank Accession No. OK066320). This sequence showed 98–99% nucleotide sequence identity with multiple BBTV isolates from India (e.g., KX219591, GU085264), Democratic Republic of Congo (DR Congo; e.g. KU687085, KU687070, KU687068), Benin (e.g. JQ437548), Burundi (e.g. JN204198), Australia (e.g. KM607586), USA (Hawaii; e.g., KM607599) and other African and South Pacific countries. To our knowledge, this constitutes the first report of BBTD in Uganda.
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    Pleurotus ostreatus is a potential biological control agent of root-knot nematodes in eggplant (Solanum melongena)
    (Frontiers Media, 2024-10-25) Nyangwire, Betty; Ocimati, Walter; Tazuba, Anthony Fredrick; Blomme, Guy; Alumai, Alfred; Onyilo, Francis
    Introduction: The management of root-knot nematodes has predominantly been based on use of chemicals, which are detrimental to the environment and human health. Biological control provides alternative management. This study evaluated the potential of using Pleurotus ostreatus, an edible mushroom species to control Meloidogyne spp. in eggplants. Methods: In vitro, the mortality of juveniles (J2) of Meloidogyne spp. were assessed i) P. ostreatus - water suspension with actively growing mycelia, and ii) different dilutions of P. ostreatus PDB broth culture filtrates. In the screen house nematicidal potential of P. ostreatus was tested on eggplants using artificially inoculated soils in a screen house. To attain this, juveniles (J2) of Meloidogyne spp. were inoculated at the base of plants in pots containing P. ostreatus colonized millet grains mixed in 3 kg of soil. The galling index (GI) (scale of 0 to 5), root growth and nematode populations in the different treatments were assessed. Results and discussion: Mortality of nematodes in the P. ostreatus - water suspension significantly increased with time, reaching over 88% at 48 h and 95% at 72 h. Mortality in undiluted filtrate was consistently significantly higher than the diluted filtrates and control without P. ostreatus. Mortality in the undiluted filtrate increased to 95% at 48 h. When 50 g of P. ostreatus-millet culture was mixed with 3 kg autoclaved pot soil, a GI of 0.95 was observed, dropping to 0.70 when the inoculum was doubled to 100 g. For the treatment without P. ostreatus, a high GI of 2.4 was scored. A significant difference in eggplant root growth and nematode population at (p = 0.02) was found across the treatments. The findings from this study for both in-vitro and pot assay suggest that P. ostreatus and its substrate are potential biological control agents for plant parasitic nematodes in eggplants.
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    Pseudocercospora fijiensis cell fusion (Fus3) gene, complete cds
    (National Center for Biotechnology Information (NCBI), 2019-08-07) Onyilo, Francis
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    Pseudocercospora fijiensis high osmolarity glycerol (Hog1) gene, complete cds
    (National Center for Biotechnology Information (NCBI), 2019-08-07) Onyilo, Francis
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    Pseudocercospora fijiensis suppressor of the lytic phenotype (Slt2) gene, complete cds
    (National Center for Biotechnology Information (NCBI), 2019-08-07) Onyilo, Francis; Stergiopoulosq, I; Chen, L.-H.; Falk, B.; Odong, T. L.; Tripathi, J. N.; Tusiime, G.; Tripathi, L
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    Silencing of the Mitogen-Activated Protein Kinases (MAPK) Fus3 and Slt2 in Pseudocercospora fijiensis Reduces Growth and Virulence on Host Plants
    (Frontiers in Plant Science, 2018) Onyilo, Francis; Tusiime, Geoffrey; Tripathi, N. Jaindra; Chen, Li-Hung; Falk, Bryce; Stergiopoulos, Ioannis; Tushemereirwe, Wilberforce; Kubiriba, Jerome; Tripathi, Leena
    Pseudocercospora fijiensis, causal agent of the black Sigatoka disease (BSD) of Musa spp., has spread globally since its discovery in Fiji 1963 to all the banana and plantain growing areas across the globe. It is becoming the most damaging and economically important disease of this crop. The identification and characterization of genes that regulate infection processes and pathogenicity in P. fijiensis will provide important knowledge for the development of disease-resistant cultivars. In many fungal plant pathogens, the Fus3 and Slt2 are reported to be essential for pathogenicity. Fus3 regulates filamentous-invasion pathways including the formation of infection structures, sporulation, virulence, and invasive and filamentous growth, whereas Slt2 is involved in the cell-wall integrity pathway, virulence, invasive growth, and colonization in host tissues. Here, we used RNAi-mediated gene silencing to investigate the role of the Slt2 and Fus3 homologs in P. fijiensis in pathogen invasiveness, growth and pathogenicity. The PfSlt2 and PfFus3 silenced P. fijiensis transformants showed significantly lower gene expression and reduced virulence, invasive growth, and lower biomass in infected leaf tissues of East African Highland Banana (EAHB). This study suggests that Slt2 and Fus3 MAPK signaling pathways play important roles in plant infection and pathogenic growth of fungal pathogens. The silencing of these vital fungal genes through host-induced gene silencing (HIG) could be an alternative strategy for developing transgenic banana and plantain resistant to BSD.
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    Spent Pleurotus ostreatus Substrate Has Potential for Controlling the Plant-Parasitic Nematode, Radopholus similis in Bananas
    (MDPI, 2025-04-26) Tazuba, Anthony Fredrick; Ocimati, Walter; Ogwal, Geofrey; Nyangwire, Betty; Onyilo, Francis; Blomme, Guy
    Spent mushroom substrate (SMS), a waste product from mushroom cultivation, in addition to being rich in essential nutrients for crop growth, contains actively growing mushroom mycelia and metabolites that suppress some plant pathogens and pests. SMS thus has potential for fostering the suppressiveness of soil-borne pathogens of farms. This study determined the potential of using the spent Pleurotus ostreatus substrate (SPoS) to suppress the plant-parasitic nematode Radopholus similis in bananas. R. similis is the most economically important nematode in bananas worldwide. The effect of SPoS on R. similis was assessed through two in vivo (potted plants) experiments between May 2023 and June 2024. Five-month-old East African highland banana (genome AAA) plantlets that are highly susceptible to R. similis were used. In the first experiment, the plantlets were established in 3 L pots containing (i) pre-sterilized soil, (ii) pre-sterilized soil inoculated with nematodes, (iii) pre-sterilized soil mixed with 30% (v/v) SPoS, (iv) pre-sterilized soil mixed with 30% (v/v) SPoS followed by nematode inoculation, (v) SPoS without soil, and (vi) SPoS without soil inoculated with nematodes. The SPoS was already decomposed; thus, it may or may not have contained active mycelia. The nematodes were introduced two weeks after the SPoS application. In the second experiment, SPoS was introduced two weeks after nematode inoculation. The SPoS treatments without soil were not evaluated in the second experiment. Both experiments were monitored over a three-month period. Each screenhouse treatment contained four plants and was replicated thrice. In the first experiment, data were collected on changes in soil nutrient content, below- and aboveground biomass, root deaths, root necrosis due to nematode damage, and R. similis population in root tissues and soil. In the second experiment, data were collected on root deaths and the number of nematodes in root tissues and the soil. The SPoS improved crop biomass yield, reduced root damage, and colonization by R. similis. The potential of SPoS to improve the management of R. similis and banana production under field conditions needs to be determined.