Browsing by Author "Nantongo, Judith S."

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    Genomic selection for resistance to mammalian bark stripping and associated chemical compounds in radiata pine
    (G3, 2022) Nantongo, Judith S.; Potts, Brad M.; Graham, Natalie J.; Fitzgerald, Hugh; O'Reilly-Wapstra, Julianne M.
    The integration of genomic data into genetic evaluations can facilitate the rapid selection of superior genotypes and accelerate the breeding cycle in trees. In this study, 390 trees from 74 control-pollinated families were genotyped using a 36K Axiom SNP array. A total of 15,624 high-quality SNPs were used to develop genomic prediction models for mammalian bark stripping, tree height, and selected primary and secondary chemical compounds in the bark. Genetic parameters from different genomic prediction methods—single-trait best linear unbiased prediction based on a marker-based relationship matrix (genomic best linear unbiased prediction), multitrait single-step genomic best linear unbiased prediction, which integrated the marker-based and pedigree-based relationship matrices (single-step genomic best linear unbiased prediction) and the single-trait generalized ridge regression—were compared to equivalent single- or multitrait pedigree-based approaches (ABLUP). The influence of the statistical distribution of data on the genetic parameters was assessed. Results indicated that the heritability estimates were increased nearly 2-fold with genomic models compared to the equivalent pedigree-based models. Predictive accuracy of the single-step genomic best linear unbiased prediction was higher than the ABLUP for most traits. Allowing for heterogeneity in marker effects through the use of generalized ridge regression did not markedly improve predictive ability over genomic best linear unbiased prediction, arguing that most of the chemical traits are modulated by many genes with small effects. Overall, the traits with low pedigree-based heritability benefited more from genomic models compared to the traits with high pedigree-based heritability. There was no evidence that data skewness or the presence of outliers affected the genomic or pedigree-based genetic estimates.
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    Nutritional prospects of jackfruit and its potential for improving dietary diversity in Uganda
    (BMC research notes, 2022) Nantongo, Judith S.; Odoi, Juventine B.; Agaba, Hillary; Gwali, Samson
    A sustainable way of providing essential nutrients from crops for the poor and undernourished is biofortification, through plant breeding. This study characterised the intraspecific variation of selected nutritional elements in the flakes and seeds of Ugandan jackfruit (Artocarpus heterophyllus) plus the phytochemical composition of leaves. The overall aim was to explore possibilities of selecting for varieties that are higher in selected essential nutrients. Selecting for nutrient dense crops has been mostly done for annual agricultural crops, and rarely for perennial fruit trees. Results: Uganda’s Jackfruit has high macronutrients, especially magnesium and calcium. This study revealed that the amounts of these macronutrients were higher than those found in commonly consumed fruits, giving jackfruit a nutritional advantage with respect to these nutrients. The varieties sampled also differed significantly (p < 0.01) for some nutrients such as vitamin C, crude fat, crude fibre, total soluble solids and juice yield, highlighting the potential for selection for targeted nutritional gains. The seeds however, had less amounts of most of the quantified nutrients that also differed among the varieties. Significant intraspecific variation of the leaf total phenolics was also observed. With regard to the quantified nutritional elements in the flakes, the ethno-varieties were separated in space along PC1 (p < 0.001), PC2 (p < 0.001) and PC3 (p < 0.01) indicating their distinctness.
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    Structuring of genetic diversity in Albizia gummifera C.A.Sm. among some East African and Madagascan populations
    (African Journal of Ecology, 2010) Nantongo, Judith S.; Okullo, John B. L.; Eilu, Gerald; Ramonta, Isabelle R.; Odee, David; Cavers, Stephen
    The fast-growing, leguminous tree Albizia gummifera C.A.Sm. (Fabaceae, Mimosoideae) is a potentially useful species for ecological restoration of degraded forests. The species has multifunctional benefits such as timber, forage and medicine. However, it also has the potential to restore degraded soils as it forms mycorrhizal and rhizobial symbiotic associations (Hall, 2004), meaning ecological and economic benefits would be obtained simultaneously.A key consideration in forest restoration is ensuring sustainability of the restored habitat, for which maximizing the suitability of planting material is important. In tree species, high levels of within-population genetic diversity and local adaptation are common phenomena. However, the strength and relative extent of local versus regional genetic structuring varies with species and depends on particular characteristics of life history (such as longevity, dispersal mechanisms and successional stage). Therefore if genetic hazards (e.g. maladaptation, inbreeding ⁄ outbreeding depression) are to be taken into account, species must be considered individually.