NRU :: Browsing by Author "Kiggundu, Andrew"

Browsing by Author "Kiggundu, Andrew"

Now showing 1 - 14 of 14

Building a bi-directional promoter binary vector from the intergenic region of Arabidopsis thaliana cab1 and cab2 divergent genes useful for plant transformation
(African Journal of Biotechnology, 2013) Tindamanyire, Jimmy M.; Townsley, Brad; Kiggundu, Andrew; Tushemereirwe, Wilberforce; Sinha, Neelima
The ability to express genes in a controlled and limited domain is essential to succeed in targeted genetic modification. Having tools by which to rapidly and conveniently generate constructs which can be assayed in a diverse array of plant species expedites research and end-product development. Targeting specifically green plant tissues offers an opportunity to effect changes to diverse processes such as water use efficiency, photosynthesis, predation and nutrition. To facilitate the generation of transgenes to be expressed in this domain, we created a series of plasmids called p2CABA based on the Arabidopsis thaliana chlorophyll a/b gene promoter, a single natural bidirectional promoter that can drive and express two different genes at the same time. Studies we carried out showed reporter gene, GUS expressed in leaves and stems but not in the roots, as expected since this endogenous promoter controls the expression of two photosynthetic genes in A. thaliana. We, therefore, utilized the intergenic region between the A. thaliana cab1 and cab2 divergent genes to design and construct a bidirectional promoter vector containing two multiple cloning sites and a gateway recombination cassette. This in turn will help minimize gene silencing and achieve desirable expression pattern of transgenes, a critical issue in plant genetic engineering and in this report we show their use in Medicago and tomato.
Components of resistance to banana weevil ( Cosmopolites sordidus ) in Musa germplasm in Uganda
(Entomologia experimentalis et applicata, 2007) Kiggundu, Andrew; Gold, Clifford S.; Labuschagne, Maryke T.; Vuylsteke, Dirk; Louw, Schalk
field screening trial undertaken in Uganda showed that a number of Musa L. (Musaceae) cultivars and hybrids displayed high levels of resistance to banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), while most highland banana cultivars tended to be susceptible to weevil attack. In this study, research was undertaken to determine modalities of resistance to banana weevil. Laboratory studies suggested that all cultivars were attractive to the weevil and that females freely oviposited on all cultivars. While some differences were found between cultivars in attractivity and egg numbers, these were not related to subsequent damage. Therefore, antixenosis does not appear to play an important role in host-plant resistance to banana weevil. Larval survivorship rates in living corms were, for the most part, low on resistant cultivars, suggesting that antibiosis mechanisms offer the primary avenues of resistance. In the laboratory, development was slower on some resistant cultivars although survivorship rates on excised corm material were not as well related to levels of resistance as that on living material. Sap appeared to play a minor role in reducing egg eclosion rates on some resistant cultivars. Methanol extracts from Kayinja, a resistant cultivar, inhibited larval development on corms of susceptible cultivars in the laboratory.
Corm damage caused by banana weevils Cosmopolites sordidus (Germar) collected from different banana growing regions in Uganda
(Agriculture & Food Security, 2018) Twesigye, Charles K.; Ssekatawa, Kenneth; Kiggundu, Andrew; Tushemereirwe, Wilberforce; Matovu, Enock; Karamura, Eldad
In this study, both healthy tissue culture plantlets and maiden suckers of the Nakitembe cultivar were used to assess the damage level variation caused by banana weevils collected from different banana growing regions. Seventy-nine (79) tissue culture plantlets and fifty (50) suckers were established in buckets in a randomized complete block design for 5 months. Ten adult weevils (5 females and 5 males) were introduced at the base of each plant, and the buckets were covered with a weevil proof mesh. Weevil damage was estimated as a percentage at 60 days after the weevil introduction by estimating the peripheral damage (PD), total cross section corm damage (XT) and above the collar damage (ACD). Results: The results showed high differences in the PD, XI, XO and XT caused by weevils from the different zones. PD and XT ranged from 4.8–50.4 to 4.2–43.8%, respectively, caused by weevils collected from Kabale and Rakai, Kabale and Wakiso, respectively, while XI and XO varied from 0.0–42.9 to 8.3–40.4%, respectively, caused by banana weevils collected from Kabale and Rakai, Kabale and Rakai, respectively. Banana weevils from Rakai caused the highest ACD of 40.4% and no such damage was caused by banana weevils collected from western Uganda. Average ACD in suckers was 19.6% and significantly higher than that in tissue culture plants (8.5%). Conclusions and recommendations: Corm damage assessment suggests the existence of banana weevil biotypes but it is recommended that follow-up studies be carried out to confirm this phenomenon.
Deleterious effects of plant cystatins against the banana weevil Cosmopolites sordidus
(Published in Collaboration with the Entomological Society of America, 2010) Kiggundu, Andrew; Muchwezi, Josephine; Van der Vyver, Christell; Viljoen, Altus; Vorster, Juan; Schluter, Urte; Kunert, Karl; Michaud, Dominique
The general potential of plant cystatins for the development of insect-resistant transgenic plants still remains to be established given the natural ability of several insects to compensate for the loss of digestive cysteine protease activities. Here we assessed the potential of cystatins for the development of banana lines resistant to the banana weevil Cosmopolites sordidus, a major pest of banana and plantain in Africa. Protease inhibitory assays were conducted with protein and methylcoumarin (MCA) peptide substrates to measure the inhibitory efficiency of different cystatins in vitro, followed by a diet assay with cystatin-infiltrated banana stem disks to monitor the impact of two plant cystatins, oryzacystatin I (OC-I, or OsCYS1) and papaya cystatin (CpCYS1), on the overall growth rate of weevil larvae. As observed earlier for other Coleoptera, banana weevils produce a variety of proteases for dietary protein digestion, including in particular Z-Phe-Arg-MCA-hydrolyzing (cathepsin L–like) and Z-Arg-Arg-MCA-hydrolyzing (cathepsin B–like) proteases active in mildly acidic conditions. Both enzyme populations were sensitive to the cysteine protease inhibitor E-64 and to different plant cystatins including OsCYS1. In line with the broad inhibitory effects of cystatins, OsCYS1 and CpCYS1 caused an important growth delay in young larvae developing for 10 days in cystatin-infiltrated banana stem disks. These promising results, which illustrate the susceptibility of C. sordidus to plant cystatins, are discussed in the light of recent hypotheses suggesting a key role for cathepsin B–like enzymes as a determinant for resistance or susceptibility to plant cystatins in Coleoptera.
Establishment of a transformation protocol for Uganda’s yellow passion fruit using the GUS gene
(African Journal of Biotechnology, 2019) Tuhaise, Samuel; Nakavuma, Jesca L.; Adriko, John; Ssekatawa, Kenneth; Kiggundu, Andrew
Horticulture is one of the fastest growing sectors in Uganda, exporting products worth US$100 million annually. Passion fruit (Passiflora edulis) growing and export is one of the critical contributors to this sector employing over a million farmers. However, a number of biotic and abiotic constraints have initiated widespread enterprise abandonment by farmers. Passiflora improvement efforts by conventional breeding has had limited success calling for research into alternative approaches such as genetic engineering. The study aimed at optimizing existing protocols to develop an efficient and reproducible Agrobacterium mediated transformation system to suit Uganda’s Passiflora cultivars. Agrobacterium tumefaciens strain AGL1 (OD600 of 0.5) harbouring pCAMBIA2301 containing the GUS (uidA) reporter gene was used to infect pre-cultured leaf discs. Leaf discs were then vacuum infiltrated for 1.5 min at 750 mmHg followed by a three day co-cultivation period on MS + acetosyringone (100 μml-1). Putatively transgenic yellow passion fruit shoots were induced on Murashige and Skoog (MS) selection media supplemented with benzylaminopurine (BAP) 8.9 μM, kanamycin (100 mgL-1mgl) and cefotaxime (500 mgL-1). Developed shoots were then transferred to elongation media (MS + 0.44 μM BAP) and later rooted on 5.37 μM naphthaleneacetic acid (NAA). Genetic transformation was monitored using GUS staining. A single independently transformed plant was confirmed by polymerase chain reaction (PCR), translating in a transformation efficiency of 0.456%. A viable in vitro transformation protocol for Uganda’s yellow passion fruit directly from leaf discs was developed using GUS reporter gene. Further investigations are required to improve the reported protocols transformation efficiency.
Experiences in sub-Saharan Africa with GM crop risk communication
(GM crops & food, 2013) Racovita, Monica; Obonyo, Dennis Ndolo; Anguzu, Robert; Bamwenda, Gratian; Kiggundu, Andrew; Maganga, Harrison
In tackling agricultural challenges, policy-makers in sub-Saharan Africa (SSA) have increasingly considered genetically modified (GM) crops as a potential tool to increase productivity and to improve product quality. Yet, as elsewhere in the world, the adoption of GM crops in SSA has been marked by controversy, encompassing not only the potential risks to animal and human health, and to the environment, but also other concerns such as ethical issues, public participation in decision-making, socio-economic factors and intellectual property rights. With these non-scientific factors complicating an already controversial situation, disseminating credible information to the public as well as facilitating stakeholder input into decision-making is essential. In SSA, there are various and innovative risk communication approaches and strategies being developed, yet a comprehensive analysis of such data is missing. This gap is addressed by giving an overview of current strategies, identifying similarities and differences between various country and institutional approaches and promoting a way forward, building on a recent workshop with risk communicators working in SSA.
Genetic diversity of aflatoxin-producing Aspergillus flavus isolated from groundnuts in selected agroecological zones of Uganda
(BMC microbiology, 2020) Acur, Amos; Arias, Renée S.; Odongo, Steven; Tuhaise, Samuel; Ssekandi, Joseph; Muhanguzi, Dennis; Adriko, John; Buah, Stephen; Kiggundu, Andrew
Background Aspergillus is the main fungal genus causing pre- and post-harvest contamination of groundnuts. Aspergillus flavus belongs to section Flavi, a group consisting of both the aflatoxigenic species (A. flavus, A. parasiticus and A. nomius) and non-aflatoxigenic species (A. oryzae, A. sojae and A. tamarii). Aflatoxins are food-borne toxic secondary metabolites produced by Aspergillus species, causing hepatic carcinoma and stunting in children and are the most toxic carcinogenic mycotoxins ever identified. Despite the well-known public health problems associated with aflatoxicosis in Uganda, information about the genetic diversity of the main aflatoxin causing fungus, Aspergillus flavus in this country is still limited. Results A cross-sectional survey was therefore carried out in three main groundnut-growing agro-ecological zones (AEZs) of Uganda; West Nile farming system, Lake Kyoga basin mixed farming system and Lake Victoria basin farming system. This was to assess the genetic diversity of A. flavus and to establish the contamination rates of groundnuts with Aspergillus species at pre- and post-harvest stages. Out of the 213 A. flavus isolates identified in this study, 96 representative isolates were fingerprinted using 16 insertion/deletion microsatellite markers. Data from fingerprinting were analyzed through Neighbor Joining while polymorphism was determined using Arlequin v 3.5. The pre- and post-harvest contamination rates were; 2.5% and 50.0% (West Nile farming system), 55.0% and 35.0% (Lake Kyoga basin mixed farming system) and 32.5% and 32.5% (Lake Victoria basin farming system) respectively. The Chi-square test showed no significant differences between pre- and post-harvest contamination rates among AEZs (p = 0.199). Only 67 out of 96 isolates produced suitable allele scores for genotypic analysis. Analysis of genetic diversity showed higher variation within populations than among populations. Two major clusters (aflatoxigenic and non-aflatoxigenic isolates) were identified as colonizing groundnuts at pre- and postharvest stages. Conclusions These findings provide a first insight on the existence of non-aflatoxigenic strains of A. flavus in Uganda. These strains are potential candidates for developing local Aspergillus biocontrol agent.
Geographic shifts in the highland cooking banana (Musa spp., group AAA-EA) production in Uganda
(International Journal of Sustainable Development & World Ecology, 1999) Gold, Clifford S.; Karamura, Eldad B.; Kiggundu, Andrew; Bagamba, Fred; Abera, Agnes M. K.
Between 1970 and 1990 Uganda witnessed the decline of the highland cooking banana from traditional growing areas in the central region, coupled with crop expansion in the country's southwest. Apprehension that the factors leading to loss ofsustainability in the central region may be replayed in extant production areas has raised concern about the future of the cooking banana in Uganda. Consequently, a multi-disciplinary study was conducted at nine central and six southwestern sites to document shifts in cooking banana production and to elucidate the causes behind these shifts. Cooking banana production in central Uganda sites fell from 18% of total food crop and 7% of total cash crop production in the 1970s to 4% and 2%, respectively, in the 1990s. Farmers identified reduced labour availability and management, increasing pest pressure and declining soil nutrient status as the major causes of decline. On-farm verification confirmed farmers' observations: weevil levels were the highest yet found in Uganda, while foliar samples indicated deficiencies in magnesium, nitrogen, and potassium. Soil nutrient deficiencies, however, appear to be a direct outcome of reduced management rather than 'soil exhaustion' as postulated by farmen. . In southwestern Uganda, the importance of the cooking banana as a cash crop has quadrupled since 1970. Banana fint penetrated the region because' of its ease of production and stability of yield. High yields attracted traders and urban market demand drove further crop expansion. With current market incentives, banana management standards have been high. Under current levels of management, it is unlikely that farmen in southwestern Uganda will experience a similar process of decline as that which occurred in the central region. However, concern remains aboqt lack of replenishment ofnutrients leaving the farm in the form offruits sold for market, a nutrient loss which may eventually lead to non-sustainability of the cropping system.
Identity of Fusarium species associated with collar rot and wilt in passion fruit (Passiflora edulis )
(Student's Journal of Health Research Africa, 2022-12-30) Nassimbwa, Florence; Matovu, Enock; Kiggundu, Andrew; Charles, Changa; Godfrey, Sseremba; Francis, Mumbanza; John, Adriko
Despite the immense contribution of passion fruits to people’s livelihood on a global scale, the crop’s productivity remains low owing to fungal diseases causing up to 100% loss. Fungi are highly variable and the identity of species or variates responsible for recently devastating passion fruit wilt and collar rot diseases had not been characterized. This study was aimed at identifying pathogens causing wilt and collar rot symptoms in passion fruits. Fungi were isolated from diseased samples collected from three locations in Central Uganda to identify Fusarium spp associated with collar rot and wilting of passion fruit. This was established by differentiating mycelium pigmentation on Potato Dextrose Agar (PDA), examining slides at X40 magnification under a light microscope for specific macro and microconidia, and amplification with specific Transcription Elongation Factor-1α, TEF 1α primers for identification of Fusarium spp. It was revealed that wilting was associated with a single species, out of 6 selected isolates from the suspected wilted plant, 3 were Fusarium spp associated with the disease in the field but only one of these isolates was proved to be a pathogenic type Fusarium oxysporium. Collar rot was associated with one pathogenic Fusarium spp out of the 6 selected isolates. The results indicate that collar rot and Fusarium wilt are each caused by specific strains of Fusarium pathogens.
In-Vitro Antifungal Potential of Dsrna Molecules On Fusarium Actin Related Protein 2/3, DNA Polymerase Delta Subunit and Adenylase Cyclase Essential Genes On Collar Rot And Wilt Pathogens Of Passionfruit
(Student's Journal of Health Research Africa, 2023-06-29) Nassimbwa, Florence; Matovu, Enock; Kiggundu, Andrew; Changa, Charles; Mumbanza, Francis; Adriko, John
In Uganda two fungal diseases have become economically important; Fusarium wilt which is caused by.Fusarium oxysporum. f.sp passiflorae (Fop) and collar rot caused by Fusarium solani (Fs). The aim of this study was to determine antifungal activity of synthetic dsRNA constructed to silence essential genes; Actin Related Protein 2/3 (D6), DNA Polymerase delta subunit (J6), and Adenylase cyclase (K6), in Fusarium from banana on Fusarium sp from passionfruit.
Levels of host plant resistance to banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), in Ugandan Musa germplasm
(Euphytica, 2003) Kiggundu, Andrew; Gold, Clifford S.; Labuschagne, Maryke T.; Vuylsteke, Dirk; Louw, Schalk
Forty-five Musa clones, including endemic and introduced cultivars plus hybrids, were evaluated for resistance against the banana weevil, Cosmopolites sordidus, in a field trial in Uganda. The predominant groups of staple crops, East African highland bananas (Musa spp. AAA) and plantains (Musaspp. AAB), as well as plantain-derived hybrids (AAB × AA), showed the highest levels of susceptibility to this pest. These were followed by dessert bananas (Musa spp. AAA), exotic bananas (Musa spp. ABB) and finally diploids of M. acuminata (AA). Hybrids of banana origin were highly resistant. Some East African highland cultivars, especially brewing types (e.g., Kabula, Bagandeseza, Ediirira), showed intermediate levels of resistance. Among the non-highland bananas, high levels of resistance were observed in Yangambi-Km5 (AAA), Cavendish (AAA), Gros Michel (AAA), Kayinja (ABB, Pisang Awak subgroup), Ndiizi (AB, Ney Poovan subgroup)and Kisubi (Ney Poovan subgroup). The highest resistance was observed in banana hybrids TMB2×7197-2, TMB2×8075-7 and the wild banana Calcutta-4 (AA). These were considered the best sources of resistance for a weevil resistance-breeding programme with the two hybrids commonly used as improved male parents.
Recombinant protease inhibitors for herbivore pest control: a multitrophic perspective
(Journal of experimental botany, 2010) Schluter, Urte; Benchabane, Meriem; Munger, Aurelie; Kiggundu, Andrew; Vorster, Juan; Goulet, Marie-Claire; Cloutier, Conrad; Michaud, Dominique
Protease inhibitors are a promising complement to Bt toxins for the development of insect-resistant transgenic crops, but their limited specificity against proteolytic enzymes and the ubiquity of protease-dependent processes in living organisms raise questions about their eventual non-target effects in agroecosystems. After a brief overview of the main factors driving the impacts of insect-resistant transgenic crops on non-target organisms, the possible effects of protease inhibitors are discussed from a multitrophic perspective, taking into account not only the target herbivore proteases but also the proteases of other organisms found along the trophic chain, including the plant itself. Major progress has been achieved in recent years towards the design of highly potent broad-spectrum inhibitors and the field deployment of protease inhibitor-expressing transgenic plants resistant to major herbivore pests. A thorough assessment of the current literature suggests that, whereas the non-specific inhibitory effects of recombinant protease inhibitors in plant food webs could often be negligible and their ‘unintended’ pleiotropic effects in planta of potential agronomic value, the innocuity of these proteins might always remain an issue to be assessed empirically, on a case-by-case basis.
Stacking three late blight resistance genes from wild species directly into African highland potato varieties confers complete field resistance to local blight races
(Plant Biotechnology Journal, 2019) Ghislain, Marc; Byarugaba, Arinaitwe Abel; Magembe, Eric; Njoroge, Anne; Rivera, Cristina; Lupe Roman, Marıa; Carlos Tovar, Jose; Gamboa, Soledad; Forbes, Gregory A.; Kreuze, Jan F.; Barekye, Alex; Kiggundu, Andrew
Considered responsible for one million deaths in Ireland and widespread famine in the European continent during the 1840s, late blight, caused by Phytophthora infestans, remains the most devastating disease of potato (Solanum tuberosum L.) with about 15%–30% annual yield loss in sub-Saharan Africa, affecting mainly smallholder farmers. We show here that the transfer of three resistance (R) genes from wild relatives [RB, Rpi-blb2 from Solanum bulbocastanum and Rpi-vnt1.1 from S. venturii] into potato provided complete resistance in the field over several seasons. We observed that the stacking of the three R genes produced a high frequency of transgenic events with resistance to late blight. In the field, 13 resistant transgenic events with the 3R-gene stack from the potato varieties ‘Desiree’ and ‘Victoria’ grew normally without showing pathogen damage and without any fungicide spray, whereas their non-transgenic equivalent varieties were rapidly killed. Characteristics of the local pathogen population suggest that the resistance to late blight may be long-lasting because it has low diversity, and essentially consists of the single lineage, 2_A1, which expresses the cognate avirulence effector genes. Yields of two transgenic events from ‘Desiree’ and ‘Victoria’ grown without fungicide to reflect small-scale farm holders were estimated to be 29 and 45 t/ha respectively. This represents a three to four-fold increase over the national average. Thus, these late blight resistant potato varieties, which are the farmers’ preferred varieties, could be rapidly adopted and bring significant income to smallholder farmers in sub-Saharan Africa.
Variation among banana weevil Cosmopolites sordidus (Germar) populations in Uganda as revealed by AFLP markers and corm damage differences
(Agriculture & Food Security, 2018) Twesigye, Charles K.; Ssekatawa, Kenneth; Kiggundu, Andrew; Tushemereirwe, Wilberforce; Matovu, Enock
The banana weevil Cosmopolites sordidus (Germar) is a major production constraint of bananas and plantains (Musa spp.) in the world. Differences in damage levels and pesticide response across regions led to the postulation that there might be considerable variation between banana weevil populations (biotypes) with varying levels of virulence. One of the most sustainable options for banana weevil control is the use of host plant resistance. While new resistant varieties are being developed through both conventional crossbreeding and biotechnology, there is a need to assess the genetic variation of banana weevil populations from eastern, central, southern, southwestern and midwest regions of Uganda to determine whether there are biotypes with different virulence levels. This would help guide new control strategies to target all the possible biotypes. The amplified fragment length polymorphism (AFLP) technique was used to analyze population genetic diversity using four primer combinations (EcoRI/MSeI). Results: Analysis of molecular variance results presented no evidence to support significant genetic variability among the banana weevil populations from eastern, central, southern, southwestern and midwest regions. Practically, all the genetic variation was found to reside within populations (97% for sites and 98% for regions), with only approximately 3% and 2% residing among populations of sites and regions, respectively. Conclusions and recommendations: AFLP markers clustered the banana weevils into two distinct populations consequently supporting the hypothesis of possible presence of banana weevil biotypes in Uganda. However, attempts should be made to make follow-up studies on the seemingly unique population of eastern Uganda using more robust molecular techniques to establish whether the eastern Uganda population constitutes a different biotype.

Browsing by Author "Kiggundu, Andrew"

Results Per Page

Sort Options