Browsing by Author "Arinaitwe, Geofrey"

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    Development of two high-yielding, consumeracceptable apple banana hybrids (Musa species, AAB genome group) with resistance to Fusarium oxysporum f. sp. cubense race 1
    (Journal of Plant Breeding and Crop Science, 2018) Buregyeya, Henry; Tumuhimbise, Robooni; Kubiriba, Jerome; Talengera, David; Nowankunda, Kephas; Arinaitwe, Geofrey; Tushemereirwe, Wilberforce K.; Karamura, Deborah; Karamura, Eldad; Rubaihayo, Patrick
    Fusarium wilt of bananas (Musa species) is caused by Fusarium oxysporum f. sp. cubense (Foc). Foc race 1 in particular affects dessert bananas in Uganda, causing >60% yield loss. This study was conducted to assess the performance of two new apple banana genotypes for bunch yield, resistance to Foc race 1 and consumer acceptability. The new apple banana genotypes (NAMU1 and NAMU2), along with two check cultivars, one susceptible but preferred by consumers (Sukali ndiizi) and the other resistant (Yangambi-KM5), were evaluated at the National Agricultural Research Laboratories in Uganda. Bunch yields of the two new apple bananas were higher than those of check cultivars by >50%. NAMU1 and Yangambi-KM5 showed no symptoms of Foc race 1, whereas NAMU2 showed mild symptoms on its corms. Sukali ndiizi showed severe pseudostem splitting and corm discoloration as the key symptoms of Foc race 1. The consumer acceptability of NAMU1 and NAMU2 was as high as that of Sukali ndiizi, implying that they can be perfect substitutes for the Foc race 1 susceptible Sukali ndiizi.
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    Expression of a rice chitinase gene in transgenic banana (‘Gros Michel’, AAA genome group) confers resistance to black leaf streak disease
    (Transgenic research, 2013) Kova´cs, Gabriella; Sa´gi, La´szlo´; Jacon, Ge´raldine; Arinaitwe, Geofrey; Busogoro, Jean-Pierre; Thiry, Els; Strosse, Hannelore; Swennen, Rony; Remy, Serge
    Transgenic banana (Musa acuminata ‘Gros Michel’) integrating either of two rice chitinase genes was generated and its resistance to Black Leaf Streak disease caused by the fungus Mycosphaerella fijiensis was tested using a leaf disk bioassay. PCR screening indicated the presence of the hpt selectable marker gene in more than 90 % of the lines tested, whereas more than three quarters of the lines contained the linked rice chitinase gene resulting in a co-transformation frequency of at least 71.4 %. Further, a unique stable integration of the transgenes in each line revealed some false negative PCR results and the expected co-transformation frequency of 100 %. Gabriella Kova´cs, La´szlo´ Sa´gi contributed equally to this work.
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    Golden bananas in the field: elevated fruit pro-vitamin A from the expression of a single banana transgene
    (Plant Biotechnology Journal, 2017) Jean-Yves, Paul; Harjeet, Khanna; Kleidon, Jennifer; Hoang, Phuong; Geijskes, Jason; Daniells, Jeff; Zaplin, Ella; Rosenberg, Yvonne; James, Anthony; Bulukani, Mlalazi; Pradeep, Deo; Arinaitwe, Geofrey; Namanya, Priver; Becker, Douglas; Tindamanyire, James; Tushemereirwe, Wilberforce; Harding, Robert; Dale, James
    Vitamin A deficiency remains one of the world's major public health problems despite food fortification and supplements strategies. Biofortification of staple crops with enhanced levels of pro-vitamin A (PVA) offers a sustainable alternative strategy to both food fortification and supplementation. As a proof of concept, PVA-biofortified transgenic Cavendish bananas were generated and field trialed in Australia with the aim of achieving a target level of 20 μg/g of dry weight (dw) β-carotene equivalent (β-CE) in the fruit. Expression of a Fe'i banana-derived phytoene synthase 2a (MtPsy2a) gene resulted in the generation of lines with PVA levels exceeding the target level with one line reaching 55 μg/g dw β-CE. Expression of the maize phytoene synthase 1 (ZmPsy1) gene, used to develop ‘Golden Rice 2’, also resulted in increased fruit PVA levels although many lines displayed undesirable phenotypes. Constitutive expression of either transgene with the maize polyubiquitin promoter increased PVA accumulation from the earliest stage of fruit development. In contrast, PVA accumulation was restricted to the late stages of fruit development when either the banana 1-aminocyclopropane-1-carboxylate oxidase or the expansin 1 promoters were used to drive the same transgenes. Wild-type plants with the longest fruit development time had also the highest fruit PVA concentrations. The results from this study suggest that early activation of the rate-limiting enzyme in the carotenoid biosynthetic pathway and extended fruit maturation time are essential factors to achieve optimal PVA concentrations in banana fruit.
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    Incidence, Damage and Management of the Major Pests and Diseases of Robusta Coffee, [Coffea canephora (Pierre Ex A. Froehner)] in Uganda
    (Journal of Agricultural Science, 2024-12-15) Kyalo, Gerald; Kagezi, Godfrey Hubby; Anyijuka, Mark; Apunyo, Peter Charles; Arinaitwe, Geofrey; Niyibigira, Emmanuel Iyamulemye
    Black Coffee Twig Borer (BCTB), Xylosandrous compactus Eichhoff (Coleoptera: Scolytidae) and Coffee Wilt Disease (CWD) are still the two main biological constraints to Robusta coffee production in Uganda. A rapid assessment survey was conducted in January 2022 in the Regions of Eastern (Busoga), Greater Masaka, Western, South western and Rwenzori to determine the status of pests and diseases in the different regions. A short-structured questionnaire with both open and closed-ended questions was administered to 268 participants that were purposively selected in different regions. At plot level, five coffee plants were selected in each of the sampled coffee farms for observation. The selected stems were checked for infestation by the stem borers and root mealy bugs (evidenced by ants moving up and down the coffee tree). The coffee canopy was divided into 2 imaginary sections—upper and lower to assess damage by leaf skeletonizers, tailed caterpillars, beetles, aphids, mealybugs, lygus, brown eye spot, coffee leaf rust, scales, aphids, berry moth and red blister. In addition, data was collected at field level parameters including: shade intensity, the most common shade trees, weed management and most common weeds (whether grasses, sedges or broadleaved), mulching intensity and mulching material, manuring intensity and common manure used, fertilizer application and type of fertilizer used, presence and type of cover crops, presence of bands and trenches as well as intensity of intercropping and the most common intercrops. Field observations revealed that the Black Coffee Twig Borer (BCTB) was responsible for the drying up of young and old coffee branches across all regions together with Coffee Wilt disease (CWD) to a smaller extent. On average, 9.4% of the primary branches were infested by BCTB. The highest damage levels of BCTB were recorded in Eastern (17.2%) and Western (12.4%) regions. Although, BCTB affected all ages of coffee, young coffee of 2-3 years was most affected. Overall, 3.9% of the sampled coffee trees were infected by Coffee Wilt Disease (CWD), with the highest incidence (8.2%) recorded in Southwestern Uganda. There is need to enhance existing management measures for coffee pests and diseases especially BCTB and CWD. Due to the high levels of spread of BCTB, this will require a community approach to sensitize farmers through meetings and media on the sustainable management of BCTB. There is also need to come up with good dissemination strategies of Coffee Wilt Disease Resistant varieties to aid their uptake and roll out a gap filling programme for coffee trees infected and destroyed by CWD across all regions using CWDr varieties.
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    Inhibition of cell death as an approach for development of transgenic resistance against Fusarium wilt disease
    (African Journal of Biotechnology, 2016) Magambo, Betty; Harjeet, Khanna; Arinaitwe, Geofrey; Tendo, Sali; Arinaitwe, Ivan Kabiita; Kubiriba, Jerome; Tushemereirwe, Wilberforce; Dale, James
    Fusarium oxysporum f. sp. cubense (Foc) is one of the major threats to dessert banana (Musa spp.) production. In Uganda, ‘Sukali Ndiizi’ is one of the most popular dessert banana cultivars and it is highly susceptible to Fusarium wilt. Development of resistant cultivars through transgenic approaches has shown to offer one of the most effective control options for most diseases. The transgenic approaches for providing plant disease resistance have mainly been through either enzymatic destruction of pathogen structures, neutralization of pathogen and its products or production of metabolites that eventually kill the pathogen. However in recent years, methods that prevent cell death of host plant after infection especially for necrotrophic pathogens like F. oxysporum have registered success in providing resistance in several crops. We investigated whether the transgenic expression of a programmed cell death inhibition gene in Sukali Ndiizi could be used to confer Fusarium resistance to Foc race 1. Embryogenic cell suspensions of cv. ‘Sukali Ndiizi, were stably transformed with a synthetic, plant-codon optimise mCed-9 gene. Twenty-eight independently transformed plant lines were regenerated. The lines were inoculated with Foc race 1 and observed for 13 weeks in small-plant glasshouse. Three transgenic lines showed significantly lower internal and external disease symptoms than the wild-type susceptible ‘Sukali Ndiizi’ banana plants used as controls. This is the first report from Africa on the generation of Fusarium wilt tolerant transgenic ‘Sukali Ndiizi’, a very popular but rapidly diminishing African dessert banana.
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    Selection of cooking banana genotypes for yield and black Sigatoka resistance in different locations in Uganda
    (Journal of Plant Breeding and Crop Science, 2016) Tumuhimbise, Robooni; Buregyeya, Henry; Barekye, Alex; Ssali, Reuben T.; Talengera, David; Kubiriba, Jerome; Muhangi, Sedrach; Namagembe, Betty; Namanya, Priver; Arinaitwe, Geofrey; Tushemereirwe, Wilberforce K.; Karamura, Deborah; Karamura, Eldad
    It is imperative to systematically evaluate new banana genotypes in different locations before national release. This enables selection and recommendation of superior genotypes as new varieties for a wider range of environments. The objective of the present study was to select banana genotypes with stable and high performance for bunch yield and leaf black Sigatoka resistance. Eleven cooking banana genotypes developed by the Uganda National Agricultural Research Organization in collaboration with Bioversity International, and two check varieties were evaluated in multi-location preliminary yield trials in Uganda. Data collected were analyzed using Additive Main Effects and Multiplicative Interaction (AMMI) model, AMMI Stability Value, and Genotype Selection Index (GSI). Genotype × location interaction was significant for all the traits assessed. Most of the new genotypes had low interaction effects with locations for bunch yield (69.2%) and black Sigatoka (92.3%). The most stable genotypes for bunch yield were NABIO815, NABIO1117, NABIO216 and NABIO306 whereas for black Sigatoka resistance, were NABIO1011, NABIO815, NABIO1009 and NABIO216. Using the GSI that defines the most desirable genotypes as those that combine high agronomic performance and stability across environments, four genotypes (NABIO306, NABIO1011, NABIO808 and NABIO1009) were selected. These genotypes, in addition to their high performance for agronomic traits and stability, had soft and yellow fruit pulp on cooking, and will be advanced on farm for further evaluation.