Browsing by Author "Wasukira, Arthur"

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    Comparative Phenotypic and Agronomic Assessment of Transgenic Potato with 3R-Gene Stack with Complete Resistance to Late Blight Disease
    (Biology, 2021) Byarugaba, Arinaitwe Abel; Baguma, Gerald; Mutebi Jjemba, Douglas; Aharinta, Kenneth Faith; Wasukira, Arthur; Magembe, Eric; Njoroge, Anne; Barekye, Alex; Ghislain, Marc
    Transgenic potato event Vic.172, expressing three naturally occurring resistance genes (R genes) conferring complete protection against late blight disease, was evaluated for resistance to late blight, phenotypic characterization, and agronomic performance in field conditions at three locations during three seasons in Uganda. These trials were conducted by comparison to the variety Victoria from which Vic.172 derives, using identical fungicide treatment, except when evaluating disease resistance. During all seasons, the transgenic event Vic.172 was confirmed to have complete resistance to late blight disease, whereas Victoria plants were completely dead by 60–80 days after planting. Tubers from Vic.172 were completely resistant to LB after artificial inoculation. The phenotypic characterization included observations of the characteristics and development of the stems, leaves, flowers, and tubers. Differences in phenotypic parameters between Vic.172 and Victoria were not statistically significant across locations and seasons. The agronomic performance observations covered sprouting, emergence, vigor, foliage growth, and yield. Differences in agronomic performance were not statistically significant except for marketable yield in one location under high productivity conditions. However, yield variation across locations and seasons was not statistically significant, but was influenced by the environment. Hence, the results of the comparative assessment of the phenotype and agronomic performance revealed that transgenic event Vic.172 did not present biologically significant differences in comparison to the variety Victoria it derives from.
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    Genome Sequencing of Xanthomonas vasicola Pathovar vasculorum Reveals Variation in Plasmids and Genes Encoding Lipopolysaccharide Synthesis, Type-IV Pilus and Type-III Secretion Effectors
    (Pathogens, 2014) Wasukira, Arthur; Coulter, Max; Al-Sowayeh, Noorah; Thwaites, Richard; Paszkiewicz, Konrad; Kubiriba, Jerome; Smith, Julian; Grant, Murray; Studholme, David J.
    Xanthomonas vasicola pathovar vasculorum (Xvv) is the bacterial agent causing gumming disease in sugarcane. Here, we compare complete genome sequences for five isolates of Xvv originating from sugarcane and one from maize. This identified two distinct types of lipopolysaccharide synthesis gene clusters among Xvv isolates: one is similar to that of Xanthomonas axonopodis pathovar citri (Xac) and is probably the ancestral type, while the other is similar to those of the sugarcane-inhabiting species, Xanthomonas sacchari. Four of six Xvv isolates harboured sequences similar to the Xac plasmid, pXAC47, and showed a distinct Type-IV pilus (T4P) sequence type, whereas the T4P locus of the other two isolates resembled that of the closely related banana pathogen, Xanthomonas campestris pathovar musacearum (Xcm). The Xvv isolate from maize has lost a gene encoding a homologue of the virulence effector, xopAF, which was present in all five of the sugarcane isolates, while xopL contained a premature stop codon in four out of six isolates. These findings shed new light on evolutionary events since the divergence of Xvv and Xcm, as well as further elucidating the relationships between the two closely related pathogens.
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    Genome-Wide Sequencing Reveals Two Major Sub-Lineages in the Genetically Monomorphic Pathogen Xanthomonas Campestris Pathovar Musacearum.
    (Genes, 2012) Wasukira, Arthur; Tayebwa, Johnbosco; Thwaites, Richard; Paszkiewicz, Konrad; Aritua, Valente; Kubiriba, Jerome; Smith, Julian; Grant, Murray; Studholme, David J.
    The bacterium Xanthomonas campestris pathovar musacearum (Xcm) is the causal agent of banana Xanthomonas wilt (BXW). This disease has devastated economies based on banana and plantain crops (Musa species) in East Africa. Here we use genome-wide sequencing to discover a set of single-nucleotide polymorphisms (SNPs) among East African isolates of Xcm. These SNPs have potential as molecular markers for phylogeographic studies of the epidemiology and spread of the pathogen. Our analysis reveals two major sub-lineages of the pathogen, suggesting that the current outbreaks of BXW on Musa species in the region may have more than one introductory event, perhaps from Ethiopia. Also, based on comparisons of genome-wide sequence data from multiple isolates of Xcm and multiple strains of X. vasicola pathovar vasculorum, we identify genes specific to Xcm that could be used to specifically detect Xcm by PCR-based methods.
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    Nitrogen and Phosphorus Optimization and Agronomic Nutrient Use Efficiency for Improved Wheat Performance
    (International Journal of Innovation and Scientific Research, 2019) Nakanwagi, Josephine; Tenywa, John S; Wobibi, Stephen; Wasukira, Arthur; Wagoire, William W.; Nakamya, Janice; Beesigamukama, Dennis; Wodada, Wilberforce
    This study was carried out to determine the optimum nitrogen and phosphorus rates for achieving optimum yields and nutrient use efficiency for wheat in highlands of Eastern Uganda. An on station randomized complete block design experiment was conducted at Buginyanya Zonal Agricultural Research and Development Institute. Two varieties Fahari and Pasa were treated with four levels of nitrogen (0, 30, 60, & 90 kg ha-1) and three levels of phosphorus (0, 7.5 &15 kg ha-1). The fertilizer treatments were each replicated three times. The highest grain yield of Pasa and Fahari was 3211kg ha-1, 2726 kg ha1 respectively obtained at a nutrient combination of 60 kg N ha-1 and 15 P kg ha-1. The same nutrient combination resulted into highest number of tillers: (Pasa 4 and Fahari 5), kernel per spike of 40 for Pasa and 32 for Fahari. Maximum total kernel weight, spike length and plant height were obtained at 90 kg N ha-1 and 7.5 kg P ha-1 nutrient combinations. Pasa produced a significantly higher Agronomic Nitrogen Use Efficiency and Agronomic Phosphorus Use Efficiency obtained at 30 kg N ha-1 and 7.5 kg P ha-1 nutrient combinations, compared to Fahari at the same N and P rates. Optimum N and P fertilizer combination for best grain yield of both wheat varieties tested is 60 kg N ha-1 and 15 kg P ha-1 combinations.
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    PCR validation of predicted virulence factors in a collection of Xanthomonas campestris (pv. musacearum and vascolurum) strains
    (African Journal of Biotechnology, 2017) Wasukira, Arthur; Tusiime, Geoffrey; Kubiriba, Jerome
    Bacterial plant pathogens belonging to the Xanthomonas genus are adapted to their host plants and are not known to colonize other environments. Xanthomonas colonize host parts such as leaves, stems and roots before entering vascular tissues and engaging in an invasive pathogenic phase. These bacterial strains have evolved strategies to adapt to life in this environment. The host-pathogen interactions of Xanthomonas vasicola (Xv) need to be well understood to properly map the target genes in the host and pathogen so as to understand the mechanism of resistance. Genotypic characterization, based on the analysis of restriction fragment length polymorphism of virulence factor fragment products was performed on members of the X. vasicola pv. musacearum (Xcm) and X. vasicola pv. vasculorum (Xvv) from varying geographical locations. The study showed that Xcm and Xvv are different from each other based on amplification of virulence factors within fragments of their DNA. Bacterial strains of similar species can have unique Type four pili (Tfp) and Tfp pilus assembly protein PilF a fimbrial biogenesis protein was amplified in all Xanthomonas strains except NCPPB1131 only. Type III effector protein RipT was confirmed to be present in all strains of Xcm and Xvv but not NCPPB1131 and NCPPB1132. All the Xcm and Xvv strains under test yielded bands of type III effector HopAF1 except Xvv206, NCPPB1131 and NCPPB1132. YopJ type III secretion system effector protein hybridizes in DNA of all Xcm strains tested but not in NCPPB1131 or NCPPB1132. This study confirmed the predicted presence or absence of virulence factors especially effectors across bacterial strains and within strains of the same species and other clusters conserved in gram negative bacteria.