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Browsing Research Articles by Author "Albrecht, Christian"

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    Exploring the genetic diversity of jackfruit (Artocarpus heterophyllus Lam.) grown in Uganda based on SSR markers
    (Genetic Resources and Crop Evolution, 2019) Nakintu, Justine; Albrecht, Christian; Müller, Christina M.; Kagoro-Rugunda, Grace; Andama, Morgan; Olet, Eunice A.; Lejju, Julius B.; Gemeinholzer, Birgit
    Artocarpus heterophyllus Lam. is an economically important tree crop that is widely cultivated in Uganda for its fruit. Despite its economic importance, little is known about the genetic diversity of jackfruit in the country. This puts the crop’s genetic resource at risk as farmers selectively grow varieties based on market demand. The study analyzed the genetic diversity of A. heterophyllus trees from 12 districts belonging to three agro-ecological zones and three political regions of Uganda. Ten SSR loci were used to assess the genetic relationship among 200 trees, 197 from Uganda and 3 out-group individuals. All SSR loci were polymorphic with an average of 10.9 alleles per locus. STRUCTURE analysis proposed two genetic clusters: Cluster 1 was composed of samples from Eastern and neighboring Central districts, and Cluster 2 which constituted out-groups and samples from Western and neighboring Central districts. Results of STRUCTURE analysis were confirmed by PCoA. Mbarara District exhibited the highest genetic diversity (He = 0.79, I = 1.71), while Kamuli (He = 0.61, I = 1.08 and Pallisa (He = 0.59, I = 1.12) displayed the lowest genetic diversity despite high abundances of jackfruit trees. Molecular variation was higher within populations than among populations. Moderate and significant genetic differentiation was registered among geographical zones, while varietal differences displayed little insignificant genetic differentiation. Soft and white pulped varieties, considered inferior on the market, harbored private alleles which may be genetically valuable resources. Therefore, sustainable utilization and conservation efforts of the jackfruit genetic resource should consider preserving inferior varieties for future crop improvement.
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    Morphological traits of jackfruit (Artocarpus heterophyllus Lam.): Indicators of diversity, selection and germplasm dispersion in Uganda
    (Elsevier, 2023-09-15) Nakintu, Justine; Andama, Morgan; Albrecht, Christian; Wangalwa, Raphael; Lejju, Julius B.; Olet, Eunice A.
    Uganda is one of the African countries with increasing production demands of jackfruit since it has gained popularity as a food and nutrition security crop with therapeutic benefits. However, the jackfruit germplasm in Uganda had not been adequately characterized to guide its production and there were reports of farmer-selection against inferior varieties. Therefore, this study comprehensively catalogued the morphological diversity of jackfruit to foster purpose-driven cultivation of jackfruit in Uganda; identified varieties and traits prone to negative selection to guide germplasm conservation efforts and established germplasm dispersion patterns to inform exchange programs of germplasm found suitable for commercial production. This was achieved using 47 qualitative and 30 quantitative traits of 249 jackfruit trees from four ethno-varieties, three administrative regions and three agro-ecological zones analyzed for the Shannon index (H'), coefficient of variation (CV), heritability (H2), and genetic advance as percentage of the mean (GAM). Seed surface color was the most variable qualitative trait (H' = 3.16) and number of fruits per tree (H2 = 99.83) and fruit weight (GCV = 69.45, PCV = 69.76) were the most diverse quantitative traits. Ethno-varieties of low economic value registered low diversity (Serebere: H' = 0.92, Namata: H' = 1.04), depicting negative selection against undesired varieties. The qualitative morphological diversity of jackfruit was highest in the Central region (H' = 1.07) and lowest in Eastern Uganda (H' = 1.02). Given the positive correlation between tree age and trunk circumference (r = 0.99, p = 0.001), the Central region with the oldest trees, largest trunks and samples with associations in Eastern and Western regions, is presumed the center of jackfruit diversity and pioneer of jackfruit cultivation in Uganda. In conclusion, jackfruit diversity in Uganda is still robust despite selection constraints. However, for future jackfruit improvements, it is vital to conserve the less preferred ethno-varieties.