Browsing by Author "Juventine Boaz Odoi"

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    Genetic diversity and population structure among Ugandan shea tree (Vitellaria paradoxa subsp. nilotica) accessions based on DarTSeq markers
    (Crop Science, 2023-06-11) Juventine Boaz Odoi; Emmanuel Amponsah Adjei; Prasad Hendre; Judith Ssali Nantongo; Alfred Adibo Ozimati; Arfang Badji; Grace Nakabonge; Richard Edema; Thomas Lapaka Odong
    Molecular markers such as single nucleotide polymorphisms (SNPs) and SilicoDArT are important in dissecting the genetic diversity of a population at DNA level. The two marker types were analyzed using the same genotyping platform. Although the two marker types were analyzed using the same genotyping platform, they were filtered using a different marker stringency. We determined the genetic diversity of 623 half-sibs of shea tree (Vitellaria paradoxa a C. F. Gaertn. nilotica) assembled from five geographical locations (Katakwi, Otuke, Amuru, Moyo, and Arua) in Uganda’s shea parklands. A total of 27,063 Diversity Arrays Technology (DArT) SNP and 9018 SilicoDArT markers were used to assess genetic diversity and population structure. The populations showed a low genetic diversity (Gst = 0.21), very low population differentiation (FST = 0.02), low-to-moderate linkage disequilibrium (r = 0.2), and Hardy–Weinberg Equilibrium (HWE = 0.1982). The study further revealed a higher genetic diversity within population (0.26) than among the population (0.21). A high level of heterozygosity was observed within individuals (0.26) and markers (0.32) revealing a high non-random association of alleles at different loci that offer opportunities to design association studies and allele transfer in marker-assisted selection in the population. The markers varied in their polymorphic information content values (SilicoDArT = 0.11) and (SNPs = 0.15) on genetic diversity. This study reveals the importance of genetic diversity and population structure analysis using high-density DArT-Seq SilicoDaRT and SNP makers in the conservation and breeding of shea tree in Uganda.
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    SilicoDArT and SNP markers for genetic diversity and population structure analysis of Trema orientalis; a fodder species
    (PLOS One, 2022-08-22) Judith Ssali Nantongo; Juventine Boaz Odoi; Hillary Agaba; Samson Gwali
    Establishing the genetic diversity and population structure of a species can guide the selection of appropriate conservation and sustainable utilization strategies. Next-generation sequencing (NGS) approaches are increasingly being used to generate multi-locus data for genetic structure determination. This study presents the genetic structure of a fodder species -Trema orientalis based on two genome-wide high-throughput diversity array technology (DArT) markers; silicoDArT and single nucleotide polymorphisms (SNPs). Genotyping of 119 individuals generated 40,650 silicoDArT and 4767 SNP markers. Both marker types had a high average scoring reproducibility (>99%). Genetic relationships explored by principal coordinates analysis (PCoA) showed that the first principal coordinate axis explained most of the variation in both the SilicoDArT (34.2%) and SNP (89.6%) marker data. The average polymorphic information content did not highly differ between silicoDArT (0.22) and SNPs (0.17) suggesting minimal differences in informativeness in the two groups of markers. The, mean observed (Ho) and expected (He) heterozygosity were low and differed between the silicoDArT and SNPs respectively, estimated at Ho = 0.08 and He = 0.05 for silicoDArT and Ho = 0.23 and He = 0.19 for SNPs. The population of T. orientalis was moder- ately differentiated (FST = 0.20–0.53) and formed 2 distinct clusters based on maximum likelihood and principal coordinates analysis. Analysis of molecular variance revealed that clusters contributed more to the variation (46.3–60.8%) than individuals (32.9–31.2%). Overall, the results suggest a high relatedness of the individuals sampled and a threatened genetic potential of T. orientalis in the wild. Therefore, genetic management activities such as ex-situ germplasm management are required for the sustainability of the species. Ex-situ conservation efforts should involve core collection of individuals from different populations to capture efficient diversity. This study demonstrates the importance of silicoDArT and SNP makers in population structure and genetic diversity analysis of Trema orientalis, useful for future genome wide studies in the species.